From 17a86be1a280efe21f72ab034ad039e1927ae237 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Sat, 22 May 2021 11:20:09 +0100
Subject: [PATCH 01/56] add grd2xyz import/doc link

---
 doc/api/index.rst     | 1 +
 pygmt/__init__.py     | 1 +
 pygmt/src/__init__.py | 1 +
 3 files changed, 3 insertions(+)

diff --git a/doc/api/index.rst b/doc/api/index.rst
index fc69a95d1e2..9ded0f5a7d6 100644
--- a/doc/api/index.rst
+++ b/doc/api/index.rst
@@ -88,6 +88,7 @@ Operations on grids:
 .. autosummary::
     :toctree: generated
 
+    grd2xyz
     grdclip
     grdcut
     grdfill
diff --git a/pygmt/__init__.py b/pygmt/__init__.py
index 5cbea0fc853..093eed8d9ba 100644
--- a/pygmt/__init__.py
+++ b/pygmt/__init__.py
@@ -32,6 +32,7 @@
     blockmean,
     blockmedian,
     config,
+    grd2xyz,
     grd2cpt,
     grdclip,
     grdcut,
diff --git a/pygmt/src/__init__.py b/pygmt/src/__init__.py
index b4855a37737..9b227b0a6fb 100644
--- a/pygmt/src/__init__.py
+++ b/pygmt/src/__init__.py
@@ -10,6 +10,7 @@
 from pygmt.src.config import config
 from pygmt.src.contour import contour
 from pygmt.src.grd2cpt import grd2cpt
+from pygmt.src.grd2xyz import grd2xyz
 from pygmt.src.grdclip import grdclip
 from pygmt.src.grdcontour import grdcontour
 from pygmt.src.grdcut import grdcut

From 7e7a7fae065b541d8fb8543bb118fdcd283c1daa Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Sat, 22 May 2021 11:22:15 +0100
Subject: [PATCH 02/56] format fix

---
 pygmt/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pygmt/__init__.py b/pygmt/__init__.py
index 093eed8d9ba..267bc5a2681 100644
--- a/pygmt/__init__.py
+++ b/pygmt/__init__.py
@@ -32,8 +32,8 @@
     blockmean,
     blockmedian,
     config,
-    grd2xyz,
     grd2cpt,
+    grd2xyz,
     grdclip,
     grdcut,
     grdfill,

From 6525ff38167215c06780f75ee935c73e8d8d335c Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Sat, 22 May 2021 11:22:42 +0100
Subject: [PATCH 03/56] create grd2xyz.py

---
 pygmt/src/grd2xyz.py | 53 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 pygmt/src/grd2xyz.py

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
new file mode 100644
index 00000000000..cd47c87a5ab
--- /dev/null
+++ b/pygmt/src/grd2xyz.py
@@ -0,0 +1,53 @@
+"""
+grd2xyz - Convert grid to data table
+"""
+from pygmt.clib import Session
+from pygmt.helpers import (
+    GMTTempFile,
+    build_arg_string,
+    fmt_docstring,
+    kwargs_to_strings,
+    use_alias,
+)
+
+
+@fmt_docstring
+@use_alias(
+    R="region",
+    V="verbose",
+)
+@kwargs_to_strings(R="sequence")
+def grd2xyz(grid, **kwargs):
+    r"""
+    Create xyz table from grid files.
+
+    Read one or more binary 2-D grid files and write out
+    xyz-triplets in ASCII [or binary] format to standard output.
+
+    Full option list at :gmt-docs:`grd2xyz.html`
+
+    {aliases}
+
+    Parameters
+    ----------
+    grid : str or xarray.DataArray
+        The file name of the input grid or the grid loaded as a DataArray.
+        This is the only required parameter.
+    {R}
+    {V}
+
+    Returns
+    -------
+    info : str
+        A string with information about the grid.
+    """
+    with GMTTempFile() as outfile:
+        with Session() as lib:
+            file_context = lib.virtualfile_from_data(check_kind="raster", data=grid)
+            with file_context as infile:
+                arg_str = " ".join(
+                    [infile, build_arg_string(kwargs), "->" + outfile.name]
+                )
+                lib.call_module("grd2xyz", arg_str)
+        result = outfile.read()
+    return result

From 13e309c7f9b93c277f9a80bbe8faac0cd095f94c Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Sat, 22 May 2021 11:36:25 +0100
Subject: [PATCH 04/56] create test_grd2xyz.py

---
 pygmt/tests/test_grd2xyz.py | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 pygmt/tests/test_grd2xyz.py

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
new file mode 100644
index 00000000000..fb2f0fb9337
--- /dev/null
+++ b/pygmt/tests/test_grd2xyz.py
@@ -0,0 +1,27 @@
+"""
+Tests for grd2xyz.
+"""
+import pytest
+from pygmt import grd2xyz
+from pygmt.datasets import load_earth_relief
+
+
+@pytest.fixture(scope="module", name="grid")
+def fixture_grid():
+    """
+    Load the grid data from the sample earth_relief file.
+    """
+    return load_earth_relief(resolution="01d", region=[-1, 1, -1, 1])
+
+
+def test_grd2xyz(grid):
+    """
+    Make sure grd2xyz works as expected.
+    """
+    xyz_data = grd2xyz(grid=grid)
+    assert xyz_data.strip().split("\n") == [
+        "-0.5 0.5 -4967",
+        "0.5 0.5 -4852",
+        "-0.5 -0.5 -4917",
+        "0.5 -0.5 -4747.5",
+    ]

From c08d717986e829c6c1de5eeb297fd31027e55b50 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Sat, 22 May 2021 12:45:31 +0100
Subject: [PATCH 05/56] spelling fix; change docstring

---
 pygmt/src/grd2xyz.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index cd47c87a5ab..b1b25abead2 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -19,10 +19,10 @@
 @kwargs_to_strings(R="sequence")
 def grd2xyz(grid, **kwargs):
     r"""
-    Create xyz table from grid files.
+    Create xyz tables from grid files.
 
-    Read one or more binary 2-D grid files and write out
-    xyz-triplets in ASCII [or binary] format to standard output.
+    Read a binary 2-D grid files and write out
+    xyz-triplets in ASCII [or binary] format to a standard output.
 
     Full option list at :gmt-docs:`grd2xyz.html`
 

From bf58dc2defc3b6ff67e4769322505d63e4ad941d Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 25 May 2021 07:52:22 +0100
Subject: [PATCH 06/56] allow specifiying format for returned xyz data

---
 pygmt/src/grd2xyz.py | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index b1b25abead2..04bc2d2733a 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -1,7 +1,10 @@
 """
 grd2xyz - Convert grid to data table
 """
+import numpy as np
+import pandas as pd
 from pygmt.clib import Session
+from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import (
     GMTTempFile,
     build_arg_string,
@@ -17,7 +20,7 @@
     V="verbose",
 )
 @kwargs_to_strings(R="sequence")
-def grd2xyz(grid, **kwargs):
+def grd2xyz(grid, format="a", **kwargs):
     r"""
     Create xyz tables from grid files.
 
@@ -33,6 +36,12 @@ def grd2xyz(grid, **kwargs):
     grid : str or xarray.DataArray
         The file name of the input grid or the grid loaded as a DataArray.
         This is the only required parameter.
+    format : str
+        Determine the format the xyz data will be returned in:
+            **a**: numpy array [Default option]
+            **d**: pandas DataFrame
+            **s**: string
+
     {R}
     {V}
 
@@ -50,4 +59,20 @@ def grd2xyz(grid, **kwargs):
                 )
                 lib.call_module("grd2xyz", arg_str)
         result = outfile.read()
+    if format == "s":
+        return result
+    data_list = []
+    for string_entry in result.strip().split("\n"):
+        float_entry = []
+        string_list = string_entry.strip().split()
+        for i in string_list:
+            float_entry.append(float(i))
+        data_list.append(float_entry)
+    data_array = np.array(data_list)
+    if format == "a":
+        result = data_array
+    elif format == "d":
+        result = pd.DataFrame(data_array)
+    else:
+        raise GMTInvalidInput("""Must specify format as either a, d, or s.""")
     return result

From 7f100d5a7b85a5f642669903f9146342c36f1cb2 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 25 May 2021 07:58:31 +0100
Subject: [PATCH 07/56] add format tests in test_grd2xyz.py

---
 pygmt/tests/test_grd2xyz.py | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index fb2f0fb9337..973f7c03b95 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -1,9 +1,12 @@
 """
 Tests for grd2xyz.
 """
+import numpy as np
+import pandas as pd
 import pytest
 from pygmt import grd2xyz
 from pygmt.datasets import load_earth_relief
+from pygmt.exceptions import GMTInvalidInput
 
 
 @pytest.fixture(scope="module", name="grid")
@@ -18,10 +21,30 @@ def test_grd2xyz(grid):
     """
     Make sure grd2xyz works as expected.
     """
-    xyz_data = grd2xyz(grid=grid)
+    xyz_data = grd2xyz(grid=grid, format="s")
     assert xyz_data.strip().split("\n") == [
         "-0.5 0.5 -4967",
         "0.5 0.5 -4852",
         "-0.5 -0.5 -4917",
         "0.5 -0.5 -4747.5",
     ]
+
+
+def test_grd2xyz_format(grid):
+    """
+    Test that correct formats are returned.
+    """
+    xyz_array = grd2xyz(grid=grid)
+    assert isinstance(xyz_array, np.ndarray)
+    xyz_df = grd2xyz(grid=grid, format="d")
+    assert isinstance(xyz_df, pd.DataFrame)
+    xyz_string = grd2xyz(grid=grid, format="s")
+    assert isinstance(xyz_string, str)
+
+
+def test_grd2xyz_invalid_format(grid):
+    """
+    Test that grd2xyz fails with incorrect format.
+    """
+    with pytest.raises(GMTInvalidInput):
+        grd2xyz(grid=grid, format=1)

From 0701d6269188f4f9366eb49dea7858a104bc9a3d Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 25 May 2021 08:02:01 +0100
Subject: [PATCH 08/56] change format parameter to xyz_format

---
 pygmt/src/grd2xyz.py        | 10 +++++-----
 pygmt/tests/test_grd2xyz.py |  8 ++++----
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 04bc2d2733a..b1c07482008 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -20,7 +20,7 @@
     V="verbose",
 )
 @kwargs_to_strings(R="sequence")
-def grd2xyz(grid, format="a", **kwargs):
+def grd2xyz(grid, xyz_format="a", **kwargs):
     r"""
     Create xyz tables from grid files.
 
@@ -36,7 +36,7 @@ def grd2xyz(grid, format="a", **kwargs):
     grid : str or xarray.DataArray
         The file name of the input grid or the grid loaded as a DataArray.
         This is the only required parameter.
-    format : str
+    xyz_format : str
         Determine the format the xyz data will be returned in:
             **a**: numpy array [Default option]
             **d**: pandas DataFrame
@@ -59,7 +59,7 @@ def grd2xyz(grid, format="a", **kwargs):
                 )
                 lib.call_module("grd2xyz", arg_str)
         result = outfile.read()
-    if format == "s":
+    if xyz_format == "s":
         return result
     data_list = []
     for string_entry in result.strip().split("\n"):
@@ -69,9 +69,9 @@ def grd2xyz(grid, format="a", **kwargs):
             float_entry.append(float(i))
         data_list.append(float_entry)
     data_array = np.array(data_list)
-    if format == "a":
+    if xyz_format == "a":
         result = data_array
-    elif format == "d":
+    elif xyz_format == "d":
         result = pd.DataFrame(data_array)
     else:
         raise GMTInvalidInput("""Must specify format as either a, d, or s.""")
diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index 973f7c03b95..d41e2d94622 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -21,7 +21,7 @@ def test_grd2xyz(grid):
     """
     Make sure grd2xyz works as expected.
     """
-    xyz_data = grd2xyz(grid=grid, format="s")
+    xyz_data = grd2xyz(grid=grid, xyz_format="s")
     assert xyz_data.strip().split("\n") == [
         "-0.5 0.5 -4967",
         "0.5 0.5 -4852",
@@ -36,9 +36,9 @@ def test_grd2xyz_format(grid):
     """
     xyz_array = grd2xyz(grid=grid)
     assert isinstance(xyz_array, np.ndarray)
-    xyz_df = grd2xyz(grid=grid, format="d")
+    xyz_df = grd2xyz(grid=grid, xyz_format="d")
     assert isinstance(xyz_df, pd.DataFrame)
-    xyz_string = grd2xyz(grid=grid, format="s")
+    xyz_string = grd2xyz(grid=grid, xyz_format="s")
     assert isinstance(xyz_string, str)
 
 
@@ -47,4 +47,4 @@ def test_grd2xyz_invalid_format(grid):
     Test that grd2xyz fails with incorrect format.
     """
     with pytest.raises(GMTInvalidInput):
-        grd2xyz(grid=grid, format=1)
+        grd2xyz(grid=grid, xyz_format=1)

From 6ac279ca75259a6c038c4cfa994efac26fee46e9 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 6 Jul 2021 15:49:46 +0100
Subject: [PATCH 09/56] Update pygmt/src/grd2xyz.py

Co-authored-by: Meghan Jones <meghanj@alum.mit.edu>
---
 pygmt/src/grd2xyz.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index b1c07482008..640d00cff1f 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -36,7 +36,7 @@ def grd2xyz(grid, xyz_format="a", **kwargs):
     grid : str or xarray.DataArray
         The file name of the input grid or the grid loaded as a DataArray.
         This is the only required parameter.
-    xyz_format : str
+    output_type : str
         Determine the format the xyz data will be returned in:
             **a**: numpy array [Default option]
             **d**: pandas DataFrame

From a226f34f12e6502483b45fd92c49ec1bcd8c08a2 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 6 Jul 2021 15:52:47 +0100
Subject: [PATCH 10/56] change xyz_format to output_type

---
 pygmt/src/grd2xyz.py        | 8 ++++----
 pygmt/tests/test_grd2xyz.py | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 640d00cff1f..1062cc27512 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -20,7 +20,7 @@
     V="verbose",
 )
 @kwargs_to_strings(R="sequence")
-def grd2xyz(grid, xyz_format="a", **kwargs):
+def grd2xyz(grid, output_type="a", **kwargs):
     r"""
     Create xyz tables from grid files.
 
@@ -59,7 +59,7 @@ def grd2xyz(grid, xyz_format="a", **kwargs):
                 )
                 lib.call_module("grd2xyz", arg_str)
         result = outfile.read()
-    if xyz_format == "s":
+    if output_type == "s":
         return result
     data_list = []
     for string_entry in result.strip().split("\n"):
@@ -69,9 +69,9 @@ def grd2xyz(grid, xyz_format="a", **kwargs):
             float_entry.append(float(i))
         data_list.append(float_entry)
     data_array = np.array(data_list)
-    if xyz_format == "a":
+    if output_type == "a":
         result = data_array
-    elif xyz_format == "d":
+    elif output_type == "d":
         result = pd.DataFrame(data_array)
     else:
         raise GMTInvalidInput("""Must specify format as either a, d, or s.""")
diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index d41e2d94622..d29dad0e56f 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -21,7 +21,7 @@ def test_grd2xyz(grid):
     """
     Make sure grd2xyz works as expected.
     """
-    xyz_data = grd2xyz(grid=grid, xyz_format="s")
+    xyz_data = grd2xyz(grid=grid, output_type="s")
     assert xyz_data.strip().split("\n") == [
         "-0.5 0.5 -4967",
         "0.5 0.5 -4852",
@@ -36,9 +36,9 @@ def test_grd2xyz_format(grid):
     """
     xyz_array = grd2xyz(grid=grid)
     assert isinstance(xyz_array, np.ndarray)
-    xyz_df = grd2xyz(grid=grid, xyz_format="d")
+    xyz_df = grd2xyz(grid=grid, output_type="d")
     assert isinstance(xyz_df, pd.DataFrame)
-    xyz_string = grd2xyz(grid=grid, xyz_format="s")
+    xyz_string = grd2xyz(grid=grid, output_type="s")
     assert isinstance(xyz_string, str)
 
 
@@ -47,4 +47,4 @@ def test_grd2xyz_invalid_format(grid):
     Test that grd2xyz fails with incorrect format.
     """
     with pytest.raises(GMTInvalidInput):
-        grd2xyz(grid=grid, xyz_format=1)
+        grd2xyz(grid=grid, output_type=1)

From 0b52451dbb28b5ad7e76fca0ab61c20dd6f0a945 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 6 Jul 2021 15:54:04 +0100
Subject: [PATCH 11/56] change default output to DataFrame

---
 pygmt/src/grd2xyz.py        | 2 +-
 pygmt/tests/test_grd2xyz.py | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 1062cc27512..effd8ed3b74 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -20,7 +20,7 @@
     V="verbose",
 )
 @kwargs_to_strings(R="sequence")
-def grd2xyz(grid, output_type="a", **kwargs):
+def grd2xyz(grid, output_type="d", **kwargs):
     r"""
     Create xyz tables from grid files.
 
diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index d29dad0e56f..bc2230b2f93 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -34,7 +34,9 @@ def test_grd2xyz_format(grid):
     """
     Test that correct formats are returned.
     """
-    xyz_array = grd2xyz(grid=grid)
+    xyz_default = grd2xyz(grid=grid)
+    assert isinstance(xyz_default, pd.DataFrame)
+    xyz_array = grd2xyz(grid=grid, output_type="a")
     assert isinstance(xyz_array, np.ndarray)
     xyz_df = grd2xyz(grid=grid, output_type="d")
     assert isinstance(xyz_df, pd.DataFrame)

From 37d366dac36b94cc0420d23962501d12c56442b0 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 6 Jul 2021 15:56:00 +0100
Subject: [PATCH 12/56] update info return options

---
 pygmt/src/grd2xyz.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index effd8ed3b74..93374eff707 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -38,8 +38,8 @@ def grd2xyz(grid, output_type="d", **kwargs):
         This is the only required parameter.
     output_type : str
         Determine the format the xyz data will be returned in:
-            **a**: numpy array [Default option]
-            **d**: pandas DataFrame
+            **a**: numpy array
+            **d**: pandas DataFrame [Default option]
             **s**: string
 
     {R}
@@ -47,8 +47,8 @@ def grd2xyz(grid, output_type="d", **kwargs):
 
     Returns
     -------
-    info : str
-        A string with information about the grid.
+    info : pandas.DataFrame or numpy.array or str
+        The xyz triplet data in a pandas DataFrame, numpy array, or string.
     """
     with GMTTempFile() as outfile:
         with Session() as lib:

From b27699a8140b175c8958c4dd66088d999ffe9d48 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Sat, 22 May 2021 11:20:09 +0100
Subject: [PATCH 13/56] add grd2xyz import/doc link

---
 doc/api/index.rst     | 1 +
 pygmt/__init__.py     | 1 +
 pygmt/src/__init__.py | 1 +
 3 files changed, 3 insertions(+)

diff --git a/doc/api/index.rst b/doc/api/index.rst
index 40ab49ac430..a7f5e6f4fae 100644
--- a/doc/api/index.rst
+++ b/doc/api/index.rst
@@ -88,6 +88,7 @@ Operations on grids:
 .. autosummary::
     :toctree: generated
 
+    grd2xyz
     grdclip
     grdcut
     grdfill
diff --git a/pygmt/__init__.py b/pygmt/__init__.py
index 972f6474286..7b7895cd89a 100644
--- a/pygmt/__init__.py
+++ b/pygmt/__init__.py
@@ -32,6 +32,7 @@
     blockmean,
     blockmedian,
     config,
+    grd2xyz,
     grd2cpt,
     grdclip,
     grdcut,
diff --git a/pygmt/src/__init__.py b/pygmt/src/__init__.py
index f8bae667f02..c20e6053d1e 100644
--- a/pygmt/src/__init__.py
+++ b/pygmt/src/__init__.py
@@ -10,6 +10,7 @@
 from pygmt.src.config import config
 from pygmt.src.contour import contour
 from pygmt.src.grd2cpt import grd2cpt
+from pygmt.src.grd2xyz import grd2xyz
 from pygmt.src.grdclip import grdclip
 from pygmt.src.grdcontour import grdcontour
 from pygmt.src.grdcut import grdcut

From 036138105c10bae966d9d19c26e3d0d73f0177b6 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Sat, 22 May 2021 11:22:15 +0100
Subject: [PATCH 14/56] format fix

---
 pygmt/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pygmt/__init__.py b/pygmt/__init__.py
index 7b7895cd89a..c590c1f736e 100644
--- a/pygmt/__init__.py
+++ b/pygmt/__init__.py
@@ -32,8 +32,8 @@
     blockmean,
     blockmedian,
     config,
-    grd2xyz,
     grd2cpt,
+    grd2xyz,
     grdclip,
     grdcut,
     grdfill,

From a9fef0737ddf773387c8dc78a869bfb2a5dbd35e Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Sat, 22 May 2021 11:22:42 +0100
Subject: [PATCH 15/56] create grd2xyz.py

---
 pygmt/src/grd2xyz.py | 53 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 pygmt/src/grd2xyz.py

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
new file mode 100644
index 00000000000..cd47c87a5ab
--- /dev/null
+++ b/pygmt/src/grd2xyz.py
@@ -0,0 +1,53 @@
+"""
+grd2xyz - Convert grid to data table
+"""
+from pygmt.clib import Session
+from pygmt.helpers import (
+    GMTTempFile,
+    build_arg_string,
+    fmt_docstring,
+    kwargs_to_strings,
+    use_alias,
+)
+
+
+@fmt_docstring
+@use_alias(
+    R="region",
+    V="verbose",
+)
+@kwargs_to_strings(R="sequence")
+def grd2xyz(grid, **kwargs):
+    r"""
+    Create xyz table from grid files.
+
+    Read one or more binary 2-D grid files and write out
+    xyz-triplets in ASCII [or binary] format to standard output.
+
+    Full option list at :gmt-docs:`grd2xyz.html`
+
+    {aliases}
+
+    Parameters
+    ----------
+    grid : str or xarray.DataArray
+        The file name of the input grid or the grid loaded as a DataArray.
+        This is the only required parameter.
+    {R}
+    {V}
+
+    Returns
+    -------
+    info : str
+        A string with information about the grid.
+    """
+    with GMTTempFile() as outfile:
+        with Session() as lib:
+            file_context = lib.virtualfile_from_data(check_kind="raster", data=grid)
+            with file_context as infile:
+                arg_str = " ".join(
+                    [infile, build_arg_string(kwargs), "->" + outfile.name]
+                )
+                lib.call_module("grd2xyz", arg_str)
+        result = outfile.read()
+    return result

From 957d8fef582fc230fdb78cdcdf29c0ee3606f2df Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Sat, 22 May 2021 11:36:25 +0100
Subject: [PATCH 16/56] create test_grd2xyz.py

---
 pygmt/tests/test_grd2xyz.py | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 pygmt/tests/test_grd2xyz.py

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
new file mode 100644
index 00000000000..fb2f0fb9337
--- /dev/null
+++ b/pygmt/tests/test_grd2xyz.py
@@ -0,0 +1,27 @@
+"""
+Tests for grd2xyz.
+"""
+import pytest
+from pygmt import grd2xyz
+from pygmt.datasets import load_earth_relief
+
+
+@pytest.fixture(scope="module", name="grid")
+def fixture_grid():
+    """
+    Load the grid data from the sample earth_relief file.
+    """
+    return load_earth_relief(resolution="01d", region=[-1, 1, -1, 1])
+
+
+def test_grd2xyz(grid):
+    """
+    Make sure grd2xyz works as expected.
+    """
+    xyz_data = grd2xyz(grid=grid)
+    assert xyz_data.strip().split("\n") == [
+        "-0.5 0.5 -4967",
+        "0.5 0.5 -4852",
+        "-0.5 -0.5 -4917",
+        "0.5 -0.5 -4747.5",
+    ]

From 5a4baa543555f9791b6b694e824596267533214e Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Sat, 22 May 2021 12:45:31 +0100
Subject: [PATCH 17/56] spelling fix; change docstring

---
 pygmt/src/grd2xyz.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index cd47c87a5ab..b1b25abead2 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -19,10 +19,10 @@
 @kwargs_to_strings(R="sequence")
 def grd2xyz(grid, **kwargs):
     r"""
-    Create xyz table from grid files.
+    Create xyz tables from grid files.
 
-    Read one or more binary 2-D grid files and write out
-    xyz-triplets in ASCII [or binary] format to standard output.
+    Read a binary 2-D grid files and write out
+    xyz-triplets in ASCII [or binary] format to a standard output.
 
     Full option list at :gmt-docs:`grd2xyz.html`
 

From 1cf9e56db9514dffc5d27102dcd01214b1d177d6 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 25 May 2021 07:52:22 +0100
Subject: [PATCH 18/56] allow specifiying format for returned xyz data

---
 pygmt/src/grd2xyz.py | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index b1b25abead2..04bc2d2733a 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -1,7 +1,10 @@
 """
 grd2xyz - Convert grid to data table
 """
+import numpy as np
+import pandas as pd
 from pygmt.clib import Session
+from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import (
     GMTTempFile,
     build_arg_string,
@@ -17,7 +20,7 @@
     V="verbose",
 )
 @kwargs_to_strings(R="sequence")
-def grd2xyz(grid, **kwargs):
+def grd2xyz(grid, format="a", **kwargs):
     r"""
     Create xyz tables from grid files.
 
@@ -33,6 +36,12 @@ def grd2xyz(grid, **kwargs):
     grid : str or xarray.DataArray
         The file name of the input grid or the grid loaded as a DataArray.
         This is the only required parameter.
+    format : str
+        Determine the format the xyz data will be returned in:
+            **a**: numpy array [Default option]
+            **d**: pandas DataFrame
+            **s**: string
+
     {R}
     {V}
 
@@ -50,4 +59,20 @@ def grd2xyz(grid, **kwargs):
                 )
                 lib.call_module("grd2xyz", arg_str)
         result = outfile.read()
+    if format == "s":
+        return result
+    data_list = []
+    for string_entry in result.strip().split("\n"):
+        float_entry = []
+        string_list = string_entry.strip().split()
+        for i in string_list:
+            float_entry.append(float(i))
+        data_list.append(float_entry)
+    data_array = np.array(data_list)
+    if format == "a":
+        result = data_array
+    elif format == "d":
+        result = pd.DataFrame(data_array)
+    else:
+        raise GMTInvalidInput("""Must specify format as either a, d, or s.""")
     return result

From 948ca7334407449e15ebd90a07b2e6e5f3a6b415 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 25 May 2021 07:58:31 +0100
Subject: [PATCH 19/56] add format tests in test_grd2xyz.py

---
 pygmt/tests/test_grd2xyz.py | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index fb2f0fb9337..973f7c03b95 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -1,9 +1,12 @@
 """
 Tests for grd2xyz.
 """
+import numpy as np
+import pandas as pd
 import pytest
 from pygmt import grd2xyz
 from pygmt.datasets import load_earth_relief
+from pygmt.exceptions import GMTInvalidInput
 
 
 @pytest.fixture(scope="module", name="grid")
@@ -18,10 +21,30 @@ def test_grd2xyz(grid):
     """
     Make sure grd2xyz works as expected.
     """
-    xyz_data = grd2xyz(grid=grid)
+    xyz_data = grd2xyz(grid=grid, format="s")
     assert xyz_data.strip().split("\n") == [
         "-0.5 0.5 -4967",
         "0.5 0.5 -4852",
         "-0.5 -0.5 -4917",
         "0.5 -0.5 -4747.5",
     ]
+
+
+def test_grd2xyz_format(grid):
+    """
+    Test that correct formats are returned.
+    """
+    xyz_array = grd2xyz(grid=grid)
+    assert isinstance(xyz_array, np.ndarray)
+    xyz_df = grd2xyz(grid=grid, format="d")
+    assert isinstance(xyz_df, pd.DataFrame)
+    xyz_string = grd2xyz(grid=grid, format="s")
+    assert isinstance(xyz_string, str)
+
+
+def test_grd2xyz_invalid_format(grid):
+    """
+    Test that grd2xyz fails with incorrect format.
+    """
+    with pytest.raises(GMTInvalidInput):
+        grd2xyz(grid=grid, format=1)

From b050cd8a2cfe1103786ba50d7014b187ca745650 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 25 May 2021 08:02:01 +0100
Subject: [PATCH 20/56] change format parameter to xyz_format

---
 pygmt/src/grd2xyz.py        | 10 +++++-----
 pygmt/tests/test_grd2xyz.py |  8 ++++----
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 04bc2d2733a..b1c07482008 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -20,7 +20,7 @@
     V="verbose",
 )
 @kwargs_to_strings(R="sequence")
-def grd2xyz(grid, format="a", **kwargs):
+def grd2xyz(grid, xyz_format="a", **kwargs):
     r"""
     Create xyz tables from grid files.
 
@@ -36,7 +36,7 @@ def grd2xyz(grid, format="a", **kwargs):
     grid : str or xarray.DataArray
         The file name of the input grid or the grid loaded as a DataArray.
         This is the only required parameter.
-    format : str
+    xyz_format : str
         Determine the format the xyz data will be returned in:
             **a**: numpy array [Default option]
             **d**: pandas DataFrame
@@ -59,7 +59,7 @@ def grd2xyz(grid, format="a", **kwargs):
                 )
                 lib.call_module("grd2xyz", arg_str)
         result = outfile.read()
-    if format == "s":
+    if xyz_format == "s":
         return result
     data_list = []
     for string_entry in result.strip().split("\n"):
@@ -69,9 +69,9 @@ def grd2xyz(grid, format="a", **kwargs):
             float_entry.append(float(i))
         data_list.append(float_entry)
     data_array = np.array(data_list)
-    if format == "a":
+    if xyz_format == "a":
         result = data_array
-    elif format == "d":
+    elif xyz_format == "d":
         result = pd.DataFrame(data_array)
     else:
         raise GMTInvalidInput("""Must specify format as either a, d, or s.""")
diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index 973f7c03b95..d41e2d94622 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -21,7 +21,7 @@ def test_grd2xyz(grid):
     """
     Make sure grd2xyz works as expected.
     """
-    xyz_data = grd2xyz(grid=grid, format="s")
+    xyz_data = grd2xyz(grid=grid, xyz_format="s")
     assert xyz_data.strip().split("\n") == [
         "-0.5 0.5 -4967",
         "0.5 0.5 -4852",
@@ -36,9 +36,9 @@ def test_grd2xyz_format(grid):
     """
     xyz_array = grd2xyz(grid=grid)
     assert isinstance(xyz_array, np.ndarray)
-    xyz_df = grd2xyz(grid=grid, format="d")
+    xyz_df = grd2xyz(grid=grid, xyz_format="d")
     assert isinstance(xyz_df, pd.DataFrame)
-    xyz_string = grd2xyz(grid=grid, format="s")
+    xyz_string = grd2xyz(grid=grid, xyz_format="s")
     assert isinstance(xyz_string, str)
 
 
@@ -47,4 +47,4 @@ def test_grd2xyz_invalid_format(grid):
     Test that grd2xyz fails with incorrect format.
     """
     with pytest.raises(GMTInvalidInput):
-        grd2xyz(grid=grid, format=1)
+        grd2xyz(grid=grid, xyz_format=1)

From 9ab970162e18b26abde61641271e8444bb6477ab Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 6 Jul 2021 15:49:46 +0100
Subject: [PATCH 21/56] Update pygmt/src/grd2xyz.py

Co-authored-by: Meghan Jones <meghanj@alum.mit.edu>
---
 pygmt/src/grd2xyz.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index b1c07482008..640d00cff1f 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -36,7 +36,7 @@ def grd2xyz(grid, xyz_format="a", **kwargs):
     grid : str or xarray.DataArray
         The file name of the input grid or the grid loaded as a DataArray.
         This is the only required parameter.
-    xyz_format : str
+    output_type : str
         Determine the format the xyz data will be returned in:
             **a**: numpy array [Default option]
             **d**: pandas DataFrame

From 891ff6c38a4f85df3d32b815d2c457c7c813dfed Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 6 Jul 2021 15:52:47 +0100
Subject: [PATCH 22/56] change xyz_format to output_type

---
 pygmt/src/grd2xyz.py        | 8 ++++----
 pygmt/tests/test_grd2xyz.py | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 640d00cff1f..1062cc27512 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -20,7 +20,7 @@
     V="verbose",
 )
 @kwargs_to_strings(R="sequence")
-def grd2xyz(grid, xyz_format="a", **kwargs):
+def grd2xyz(grid, output_type="a", **kwargs):
     r"""
     Create xyz tables from grid files.
 
@@ -59,7 +59,7 @@ def grd2xyz(grid, xyz_format="a", **kwargs):
                 )
                 lib.call_module("grd2xyz", arg_str)
         result = outfile.read()
-    if xyz_format == "s":
+    if output_type == "s":
         return result
     data_list = []
     for string_entry in result.strip().split("\n"):
@@ -69,9 +69,9 @@ def grd2xyz(grid, xyz_format="a", **kwargs):
             float_entry.append(float(i))
         data_list.append(float_entry)
     data_array = np.array(data_list)
-    if xyz_format == "a":
+    if output_type == "a":
         result = data_array
-    elif xyz_format == "d":
+    elif output_type == "d":
         result = pd.DataFrame(data_array)
     else:
         raise GMTInvalidInput("""Must specify format as either a, d, or s.""")
diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index d41e2d94622..d29dad0e56f 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -21,7 +21,7 @@ def test_grd2xyz(grid):
     """
     Make sure grd2xyz works as expected.
     """
-    xyz_data = grd2xyz(grid=grid, xyz_format="s")
+    xyz_data = grd2xyz(grid=grid, output_type="s")
     assert xyz_data.strip().split("\n") == [
         "-0.5 0.5 -4967",
         "0.5 0.5 -4852",
@@ -36,9 +36,9 @@ def test_grd2xyz_format(grid):
     """
     xyz_array = grd2xyz(grid=grid)
     assert isinstance(xyz_array, np.ndarray)
-    xyz_df = grd2xyz(grid=grid, xyz_format="d")
+    xyz_df = grd2xyz(grid=grid, output_type="d")
     assert isinstance(xyz_df, pd.DataFrame)
-    xyz_string = grd2xyz(grid=grid, xyz_format="s")
+    xyz_string = grd2xyz(grid=grid, output_type="s")
     assert isinstance(xyz_string, str)
 
 
@@ -47,4 +47,4 @@ def test_grd2xyz_invalid_format(grid):
     Test that grd2xyz fails with incorrect format.
     """
     with pytest.raises(GMTInvalidInput):
-        grd2xyz(grid=grid, xyz_format=1)
+        grd2xyz(grid=grid, output_type=1)

From 02cd02fb886e4e5290f8c245a2ad8a5f9199a37e Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 6 Jul 2021 15:54:04 +0100
Subject: [PATCH 23/56] change default output to DataFrame

---
 pygmt/src/grd2xyz.py        | 2 +-
 pygmt/tests/test_grd2xyz.py | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 1062cc27512..effd8ed3b74 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -20,7 +20,7 @@
     V="verbose",
 )
 @kwargs_to_strings(R="sequence")
-def grd2xyz(grid, output_type="a", **kwargs):
+def grd2xyz(grid, output_type="d", **kwargs):
     r"""
     Create xyz tables from grid files.
 
diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index d29dad0e56f..bc2230b2f93 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -34,7 +34,9 @@ def test_grd2xyz_format(grid):
     """
     Test that correct formats are returned.
     """
-    xyz_array = grd2xyz(grid=grid)
+    xyz_default = grd2xyz(grid=grid)
+    assert isinstance(xyz_default, pd.DataFrame)
+    xyz_array = grd2xyz(grid=grid, output_type="a")
     assert isinstance(xyz_array, np.ndarray)
     xyz_df = grd2xyz(grid=grid, output_type="d")
     assert isinstance(xyz_df, pd.DataFrame)

From 00bece0c12e91079948ec766ce1c02739f5fc1e8 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 6 Jul 2021 15:56:00 +0100
Subject: [PATCH 24/56] update info return options

---
 pygmt/src/grd2xyz.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index effd8ed3b74..93374eff707 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -38,8 +38,8 @@ def grd2xyz(grid, output_type="d", **kwargs):
         This is the only required parameter.
     output_type : str
         Determine the format the xyz data will be returned in:
-            **a**: numpy array [Default option]
-            **d**: pandas DataFrame
+            **a**: numpy array
+            **d**: pandas DataFrame [Default option]
             **s**: string
 
     {R}
@@ -47,8 +47,8 @@ def grd2xyz(grid, output_type="d", **kwargs):
 
     Returns
     -------
-    info : str
-        A string with information about the grid.
+    info : pandas.DataFrame or numpy.array or str
+        The xyz triplet data in a pandas DataFrame, numpy array, or string.
     """
     with GMTTempFile() as outfile:
         with Session() as lib:

From 01613ff8e0017374e0c60ca7abff088cd09bc217 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Fri, 16 Jul 2021 16:32:44 +0100
Subject: [PATCH 25/56] change output name to "data" from "info"

---
 pygmt/src/grd2xyz.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 93374eff707..e423dfb9ee6 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -47,7 +47,7 @@ def grd2xyz(grid, output_type="d", **kwargs):
 
     Returns
     -------
-    info : pandas.DataFrame or numpy.array or str
+    data : pandas.DataFrame or numpy.array or str
         The xyz triplet data in a pandas DataFrame, numpy array, or string.
     """
     with GMTTempFile() as outfile:

From 3da6dda19284acbd6c0a88bacabc06617e77bd36 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Fri, 16 Jul 2021 16:37:22 +0100
Subject: [PATCH 26/56] Apply suggestions from code review

Co-authored-by: Meghan Jones <meghanj@alum.mit.edu>
---
 pygmt/src/grd2xyz.py | 50 +++++++++++++++++++++-----------------------
 1 file changed, 24 insertions(+), 26 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index e423dfb9ee6..de4cbc06bc4 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -20,12 +20,12 @@
     V="verbose",
 )
 @kwargs_to_strings(R="sequence")
-def grd2xyz(grid, output_type="d", **kwargs):
+def grd2xyz(grid, output_type="d", outfile=None, **kwargs):
     r"""
-    Create xyz tables from grid files.
+    Convert grid to data table.
 
-    Read a binary 2-D grid files and write out
-    xyz-triplets in ASCII [or binary] format to a standard output.
+    Read a grid and output xyz-triplets as a numpy array,
+    pandas DataFrame, string, or ASCII [or binary] file.
 
     Full option list at :gmt-docs:`grd2xyz.html`
 
@@ -41,7 +41,8 @@ def grd2xyz(grid, output_type="d", **kwargs):
             **a**: numpy array
             **d**: pandas DataFrame [Default option]
             **s**: string
-
+    outfile : str
+        The file name for the output ASCII file.
     {R}
     {V}
 
@@ -50,29 +51,26 @@ def grd2xyz(grid, output_type="d", **kwargs):
     data : pandas.DataFrame or numpy.array or str
         The xyz triplet data in a pandas DataFrame, numpy array, or string.
     """
-    with GMTTempFile() as outfile:
+    if output_type not in ["a", "d", "s"]:
+        raise GMTInvalidInput("""Must specify format as either a, d, or s.""")
+    if output_type == "s" and outfile is None:
+        raise GMTInvalidInput("""Must specify outfile for ASCII output.""")
+
+    with GMTTempFile() as tmpfile:
         with Session() as lib:
             file_context = lib.virtualfile_from_data(check_kind="raster", data=grid)
             with file_context as infile:
-                arg_str = " ".join(
-                    [infile, build_arg_string(kwargs), "->" + outfile.name]
-                )
+                if outfile is None:
+                    outfile = tmpfile.name
+                arg_str = " ".join([infile, build_arg_string(kwargs), "->" + outfile])
                 lib.call_module("grd2xyz", arg_str)
-        result = outfile.read()
-    if output_type == "s":
-        return result
-    data_list = []
-    for string_entry in result.strip().split("\n"):
-        float_entry = []
-        string_list = string_entry.strip().split()
-        for i in string_list:
-            float_entry.append(float(i))
-        data_list.append(float_entry)
-    data_array = np.array(data_list)
-    if output_type == "a":
-        result = data_array
-    elif output_type == "d":
-        result = pd.DataFrame(data_array)
-    else:
-        raise GMTInvalidInput("""Must specify format as either a, d, or s.""")
+
+        # Read temporary csv output to a pandas table
+        if outfile == tmpfile.name:  # if user did not set outfile, return pd.DataFrame
+            result = pd.read_csv(tmpfile.name, sep="\t", header=None, comment=">")
+        elif outfile != tmpfile.name:  # return None if outfile set, output in outfile
+            result = None
+
+        if output_type == "a":
+            result = result.to_numpy()
     return result

From 2dcf859b094d2a33f985c610872a9a8e3b62b13d Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Fri, 16 Jul 2021 16:53:32 +0100
Subject: [PATCH 27/56] remove numpy import

---
 pygmt/src/grd2xyz.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index de4cbc06bc4..3eeb9fc02e3 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -1,7 +1,6 @@
 """
 grd2xyz - Convert grid to data table
 """
-import numpy as np
 import pandas as pd
 from pygmt.clib import Session
 from pygmt.exceptions import GMTInvalidInput

From 283d5156c2638f3d34708ad5a08ff6c4d65ee3a3 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Fri, 16 Jul 2021 16:54:38 +0100
Subject: [PATCH 28/56] update test_grd2xyz.py

---
 pygmt/tests/test_grd2xyz.py | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index bc2230b2f93..08861765c0f 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -21,13 +21,8 @@ def test_grd2xyz(grid):
     """
     Make sure grd2xyz works as expected.
     """
-    xyz_data = grd2xyz(grid=grid, output_type="s")
-    assert xyz_data.strip().split("\n") == [
-        "-0.5 0.5 -4967",
-        "0.5 0.5 -4852",
-        "-0.5 -0.5 -4917",
-        "0.5 -0.5 -4747.5",
-    ]
+    xyz_data = grd2xyz(grid=grid, output_type="a")
+    assert xyz_data.shape == (4, 3)
 
 
 def test_grd2xyz_format(grid):
@@ -40,8 +35,6 @@ def test_grd2xyz_format(grid):
     assert isinstance(xyz_array, np.ndarray)
     xyz_df = grd2xyz(grid=grid, output_type="d")
     assert isinstance(xyz_df, pd.DataFrame)
-    xyz_string = grd2xyz(grid=grid, output_type="s")
-    assert isinstance(xyz_string, str)
 
 
 def test_grd2xyz_invalid_format(grid):
@@ -50,3 +43,11 @@ def test_grd2xyz_invalid_format(grid):
     """
     with pytest.raises(GMTInvalidInput):
         grd2xyz(grid=grid, output_type=1)
+
+
+def test_grd2xyz_no_outfile(grid):
+    """
+    Test that grd2xyz fails when a string output is set with no outfile.
+    """
+    with pytest.raises(GMTInvalidInput):
+        grd2xyz(grid=grid, output_type="s")

From 29c8be6a6255120cf5b277f34b812a226ee69da3 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Wed, 25 Aug 2021 18:16:23 +0100
Subject: [PATCH 29/56] Apply suggestions from code review

Co-authored-by: Meghan Jones <meghanj@alum.mit.edu>
---
 pygmt/src/grd2xyz.py        | 41 +++++++++++++++++++++++--------------
 pygmt/tests/test_grd2xyz.py |  8 ++++----
 2 files changed, 30 insertions(+), 19 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 3eeb9fc02e3..a6ce1da08b5 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -19,12 +19,12 @@
     V="verbose",
 )
 @kwargs_to_strings(R="sequence")
-def grd2xyz(grid, output_type="d", outfile=None, **kwargs):
+def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
     r"""
     Convert grid to data table.
 
-    Read a grid and output xyz-triplets as a numpy array,
-    pandas DataFrame, string, or ASCII [or binary] file.
+    Read a grid and output xyz-triplets as a :class:`numpy.ndarray`,
+    :class:`pandas.DataFrame`, or ASCII file.
 
     Full option list at :gmt-docs:`grd2xyz.html`
 
@@ -33,13 +33,15 @@ def grd2xyz(grid, output_type="d", outfile=None, **kwargs):
     Parameters
     ----------
     grid : str or xarray.DataArray
-        The file name of the input grid or the grid loaded as a DataArray.
-        This is the only required parameter.
+        The file name of the input grid or the grid loaded as a
+        :class:`xarray.DataArray`. This is the only required parameter.
     output_type : str
-        Determine the format the xyz data will be returned in:
-            **a**: numpy array
-            **d**: pandas DataFrame [Default option]
-            **s**: string
+        Determine the format the xyz data will be returned in [Default is
+        ``pandas``]:
+
+            - ``numpy`` - :class:`numpy.ndarray`
+            - ``pandas``-  :class:`pandas.DataFrame`
+            - ``file`` - ASCII file (requires ``outfile``)
     outfile : str
         The file name for the output ASCII file.
     {R}
@@ -47,12 +49,21 @@ def grd2xyz(grid, output_type="d", outfile=None, **kwargs):
 
     Returns
     -------
-    data : pandas.DataFrame or numpy.array or str
-        The xyz triplet data in a pandas DataFrame, numpy array, or string.
+    ret : pandas.DataFrame or numpy.ndarray or None
+        Return type depends on ``outfile`` and ``output_type``:
+
+        - None if ``outfile`` is set (output will be stored in file set by
+          ``outfile``)
+        - :class:`pandas.DataFrame` or :class:`numpy.ndarray` if ``outfile`` is
+          not set (depends on ``output_type`` [Default is
+          :class:`pandas.DataFrame`])
+
     """
-    if output_type not in ["a", "d", "s"]:
-        raise GMTInvalidInput("""Must specify format as either a, d, or s.""")
-    if output_type == "s" and outfile is None:
+    if output_type not in ["numpy", "pandas", "file"]:
+        raise GMTInvalidInput(
+            """Must specify format as either numpy, pandas, or file."""
+        )
+    if output_type == "file" and outfile is None:
         raise GMTInvalidInput("""Must specify outfile for ASCII output.""")
 
     with GMTTempFile() as tmpfile:
@@ -70,6 +81,6 @@ def grd2xyz(grid, output_type="d", outfile=None, **kwargs):
         elif outfile != tmpfile.name:  # return None if outfile set, output in outfile
             result = None
 
-        if output_type == "a":
+        if output_type == "numpy":
             result = result.to_numpy()
     return result
diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index 08861765c0f..32df9886f16 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -21,7 +21,7 @@ def test_grd2xyz(grid):
     """
     Make sure grd2xyz works as expected.
     """
-    xyz_data = grd2xyz(grid=grid, output_type="a")
+    xyz_data = grd2xyz(grid=grid, output_type="numpy")
     assert xyz_data.shape == (4, 3)
 
 
@@ -31,9 +31,9 @@ def test_grd2xyz_format(grid):
     """
     xyz_default = grd2xyz(grid=grid)
     assert isinstance(xyz_default, pd.DataFrame)
-    xyz_array = grd2xyz(grid=grid, output_type="a")
+    xyz_array = grd2xyz(grid=grid, output_type="numpy")
     assert isinstance(xyz_array, np.ndarray)
-    xyz_df = grd2xyz(grid=grid, output_type="d")
+    xyz_df = grd2xyz(grid=grid, output_type="pandas")
     assert isinstance(xyz_df, pd.DataFrame)
 
 
@@ -50,4 +50,4 @@ def test_grd2xyz_no_outfile(grid):
     Test that grd2xyz fails when a string output is set with no outfile.
     """
     with pytest.raises(GMTInvalidInput):
-        grd2xyz(grid=grid, output_type="s")
+        grd2xyz(grid=grid, output_type="file")

From c4549e418f406495e91f147fdfa0834dadc3d0cc Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Mon, 30 Aug 2021 11:32:38 +0100
Subject: [PATCH 30/56] Apply suggestions from code review

Co-authored-by: Wei Ji <23487320+weiji14@users.noreply.github.com>
---
 pygmt/src/grd2xyz.py | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index a6ce1da08b5..baee7cb3c16 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -1,6 +1,8 @@
 """
 grd2xyz - Convert grid to data table
 """
+import warnings
+
 import pandas as pd
 from pygmt.clib import Session
 from pygmt.exceptions import GMTInvalidInput
@@ -40,7 +42,7 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
         ``pandas``]:
 
             - ``numpy`` - :class:`numpy.ndarray`
-            - ``pandas``-  :class:`pandas.DataFrame`
+            - ``pandas``- :class:`pandas.DataFrame`
             - ``file`` - ASCII file (requires ``outfile``)
     outfile : str
         The file name for the output ASCII file.
@@ -63,6 +65,13 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
         raise GMTInvalidInput(
             """Must specify format as either numpy, pandas, or file."""
         )
+    if outfile is not None and output_type != "file":
+        msg = (
+            f"Changing `output_type` of grd2xyz from '{output_type}' to 'file' "
+            "since `outfile` parameter is set. Please use `output_type='file'` "
+            "to silence this warning."
+        )
+        warnings.warn(msg, category=RuntimeWarning, stacklevel=2)
     if output_type == "file" and outfile is None:
         raise GMTInvalidInput("""Must specify outfile for ASCII output.""")
 

From 66761a8e0ad41a0be610138e02270e9665611f2d Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Mon, 30 Aug 2021 18:25:47 +0100
Subject: [PATCH 31/56] Apply suggestions from code review

Co-authored-by: Wei Ji <23487320+weiji14@users.noreply.github.com>
---
 pygmt/src/grd2xyz.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index baee7cb3c16..b69c65ceca2 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -72,7 +72,8 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
             "to silence this warning."
         )
         warnings.warn(msg, category=RuntimeWarning, stacklevel=2)
-    if output_type == "file" and outfile is None:
+        output_type = "file"
+    elif output_type == "file" and outfile is None:
         raise GMTInvalidInput("""Must specify outfile for ASCII output.""")
 
     with GMTTempFile() as tmpfile:

From 0a525b623e5dcb6deb56a0a09cc5c78dba6f390c Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Mon, 30 Aug 2021 18:57:35 +0100
Subject: [PATCH 32/56] add test_grd2xyz_file_output()

---
 pygmt/tests/test_grd2xyz.py | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index 32df9886f16..e3574161756 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -1,12 +1,15 @@
 """
 Tests for grd2xyz.
 """
+import os
+
 import numpy as np
 import pandas as pd
 import pytest
 from pygmt import grd2xyz
 from pygmt.datasets import load_earth_relief
 from pygmt.exceptions import GMTInvalidInput
+from pygmt.helpers import GMTTempFile
 
 
 @pytest.fixture(scope="module", name="grid")
@@ -37,6 +40,16 @@ def test_grd2xyz_format(grid):
     assert isinstance(xyz_df, pd.DataFrame)
 
 
+def test_grd2xyz_file_output(grid):
+    """
+    Test that grd2xyz returns a file output when it is specified.
+    """
+    with GMTTempFile(suffix=".xyz") as tmpfile:
+        result = grd2xyz(grid=grid, outfile=tmpfile.name, output_type="file")
+        assert result is None  # return value is None
+        assert os.path.exists(path=tmpfile.name)  # check that outfile exists
+
+
 def test_grd2xyz_invalid_format(grid):
     """
     Test that grd2xyz fails with incorrect format.

From 8de23a8f90fef1a2aa18b5df6d27590321d8a9b9 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 31 Aug 2021 17:46:13 +0100
Subject: [PATCH 33/56] assign column names in dataframe

---
 pygmt/src/grd2xyz.py        | 9 ++++++++-
 pygmt/tests/test_grd2xyz.py | 4 ++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index b69c65ceca2..62d6f996c16 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -4,6 +4,7 @@
 import warnings
 
 import pandas as pd
+import xarray as xr
 from pygmt.clib import Session
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import (
@@ -75,6 +76,10 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
         output_type = "file"
     elif output_type == "file" and outfile is None:
         raise GMTInvalidInput("""Must specify outfile for ASCII output.""")
+    dataframe_header = ["x", "y", "z"]
+    if type(grid) == xr.DataArray and output_type == "pandas":
+        if len(grid.dims) == 3:
+            dataframe_header = grid.dims
 
     with GMTTempFile() as tmpfile:
         with Session() as lib:
@@ -87,7 +92,9 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
 
         # Read temporary csv output to a pandas table
         if outfile == tmpfile.name:  # if user did not set outfile, return pd.DataFrame
-            result = pd.read_csv(tmpfile.name, sep="\t", header=None, comment=">")
+            result = pd.read_csv(
+                tmpfile.name, sep="\t", names=dataframe_header, comment=">"
+            )
         elif outfile != tmpfile.name:  # return None if outfile set, output in outfile
             result = None
 
diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index e3574161756..aea88dee851 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -6,6 +6,7 @@
 import numpy as np
 import pandas as pd
 import pytest
+import xarray as xr
 from pygmt import grd2xyz
 from pygmt.datasets import load_earth_relief
 from pygmt.exceptions import GMTInvalidInput
@@ -34,10 +35,13 @@ def test_grd2xyz_format(grid):
     """
     xyz_default = grd2xyz(grid=grid)
     assert isinstance(xyz_default, pd.DataFrame)
+    print(type(list(xyz_default.columns)))
+    assert list(xyz_default.columns) == ["x", "y", "z"]
     xyz_array = grd2xyz(grid=grid, output_type="numpy")
     assert isinstance(xyz_array, np.ndarray)
     xyz_df = grd2xyz(grid=grid, output_type="pandas")
     assert isinstance(xyz_df, pd.DataFrame)
+    assert list(xyz_df.columns) == ["x", "y", "z"]
 
 
 def test_grd2xyz_file_output(grid):

From 938532a2f68e712299900f79f6345a7bed60dbea Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 31 Aug 2021 17:48:18 +0100
Subject: [PATCH 34/56] remove unused import

---
 pygmt/tests/test_grd2xyz.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index aea88dee851..948ec886505 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -6,7 +6,6 @@
 import numpy as np
 import pandas as pd
 import pytest
-import xarray as xr
 from pygmt import grd2xyz
 from pygmt.datasets import load_earth_relief
 from pygmt.exceptions import GMTInvalidInput

From 161c94bf0e9f22fabfc8ab82d2346c434af07e45 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 31 Aug 2021 17:49:44 +0100
Subject: [PATCH 35/56] adding comments

---
 pygmt/src/grd2xyz.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 62d6f996c16..cbc277a300c 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -76,7 +76,9 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
         output_type = "file"
     elif output_type == "file" and outfile is None:
         raise GMTInvalidInput("""Must specify outfile for ASCII output.""")
+    # Set the default column names for the pandas dataframe header
     dataframe_header = ["x", "y", "z"]
+    # Set the column names to match an input DataArray as the grid
     if type(grid) == xr.DataArray and output_type == "pandas":
         if len(grid.dims) == 3:
             dataframe_header = grid.dims

From 317a3ddd129bbfa01229d03fbdbe0edca62b8e30 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Wed, 1 Sep 2021 16:02:00 +0100
Subject: [PATCH 36/56] adding test_grd2xyz_outfile_incorrect_output_type

---
 pygmt/tests/test_grd2xyz.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index 948ec886505..c244760cd72 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -67,3 +67,13 @@ def test_grd2xyz_no_outfile(grid):
     """
     with pytest.raises(GMTInvalidInput):
         grd2xyz(grid=grid, output_type="file")
+
+
+def test_grd2xyz_outfile_incorrect_output_type(grid):
+    """
+    Test that grd2xyz raises a warning when an outfile name is set but the
+    output_type is not set to file is set with no outfile.
+    """
+    with pytest.warns(RuntimeWarning):
+        with GMTTempFile(suffix=".xyz") as tmpfile:
+            grd2xyz(grid=grid, outfile=tmpfile.name, output_type="numpy")

From 41051a9a08e196ba5fec63ddf585e528d45c54b9 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Wed, 1 Sep 2021 16:06:13 +0100
Subject: [PATCH 37/56] style fix

---
 pygmt/src/grd2xyz.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index cbc277a300c..b655aa54c6a 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -79,7 +79,7 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
     # Set the default column names for the pandas dataframe header
     dataframe_header = ["x", "y", "z"]
     # Set the column names to match an input DataArray as the grid
-    if type(grid) == xr.DataArray and output_type == "pandas":
+    if isinstance(grid, xr.DataArray) == xr.DataArray and output_type == "pandas":
         if len(grid.dims) == 3:
             dataframe_header = grid.dims
 

From 9eebee3b679f764bd186381b1f97af894f35843e Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Thu, 2 Sep 2021 08:12:11 +0100
Subject: [PATCH 38/56] Apply suggestions from code review

Co-authored-by: Wei Ji <23487320+weiji14@users.noreply.github.com>
---
 pygmt/src/grd2xyz.py        | 5 ++---
 pygmt/tests/test_grd2xyz.py | 7 ++++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index b655aa54c6a..3bead249ca5 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -79,9 +79,8 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
     # Set the default column names for the pandas dataframe header
     dataframe_header = ["x", "y", "z"]
     # Set the column names to match an input DataArray as the grid
-    if isinstance(grid, xr.DataArray) == xr.DataArray and output_type == "pandas":
-        if len(grid.dims) == 3:
-            dataframe_header = grid.dims
+    if isinstance(grid, xr.DataArray) and output_type == "pandas":
+        dataframe_header = grid.dims + (grid.name,)
 
     with GMTTempFile() as tmpfile:
         with Session() as lib:
diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index c244760cd72..8b6c6cb3bed 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -34,8 +34,7 @@ def test_grd2xyz_format(grid):
     """
     xyz_default = grd2xyz(grid=grid)
     assert isinstance(xyz_default, pd.DataFrame)
-    print(type(list(xyz_default.columns)))
-    assert list(xyz_default.columns) == ["x", "y", "z"]
+    assert list(xyz_default.columns) == ["lon", "lat", "elevation"]
     xyz_array = grd2xyz(grid=grid, output_type="numpy")
     assert isinstance(xyz_array, np.ndarray)
     xyz_df = grd2xyz(grid=grid, output_type="pandas")
@@ -76,4 +75,6 @@ def test_grd2xyz_outfile_incorrect_output_type(grid):
     """
     with pytest.warns(RuntimeWarning):
         with GMTTempFile(suffix=".xyz") as tmpfile:
-            grd2xyz(grid=grid, outfile=tmpfile.name, output_type="numpy")
+            result = grd2xyz(grid=grid, outfile=tmpfile.name, output_type="numpy")
+            assert result is None  # return value is None
+            assert os.path.exists(path=tmpfile.name)  # check that outfile exists

From 3ac3642e553cee5a778f6449d07830c865f2aa3b Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 14 Sep 2021 07:42:57 -0400
Subject: [PATCH 39/56] Apply suggestions from code review

Co-authored-by: Meghan Jones <meghanj@alum.mit.edu>
---
 pygmt/tests/test_grd2xyz.py | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index 8b6c6cb3bed..ab08543658a 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -17,7 +17,7 @@ def fixture_grid():
     """
     Load the grid data from the sample earth_relief file.
     """
-    return load_earth_relief(resolution="01d", region=[-1, 1, -1, 1])
+    return load_earth_relief(resolution="01d", region=[-1, 1, 3, 5])
 
 
 def test_grd2xyz(grid):
@@ -32,9 +32,17 @@ def test_grd2xyz_format(grid):
     """
     Test that correct formats are returned.
     """
+    lon = -0.5
+    lat = 3.5
+    orig_val = grid.sel(lon=lon, lat=lat).to_numpy()
     xyz_default = grd2xyz(grid=grid)
+    xyz_val = xyz_default[(xyz_default["lon"] == lon) & (xyz_default["lat"] == lat)][
+        "elevation"
+    ].to_numpy()
     assert isinstance(xyz_default, pd.DataFrame)
-    assert list(xyz_default.columns) == ["lon", "lat", "elevation"]
+    assert orig_val.size == 1
+    assert xyz_val.size == 1
+    np.testing.assert_allclose(orig_val, xyz_val)
     xyz_array = grd2xyz(grid=grid, output_type="numpy")
     assert isinstance(xyz_array, np.ndarray)
     xyz_df = grd2xyz(grid=grid, output_type="pandas")

From 81b051158ddd988c5d33631a7f3cb57865b24782 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Tue, 14 Sep 2021 20:05:44 -0400
Subject: [PATCH 40/56] Update pygmt/src/grd2xyz.py

Co-authored-by: Meghan Jones <meghanj@alum.mit.edu>
---
 pygmt/src/grd2xyz.py | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 3bead249ca5..d50f970e262 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -76,11 +76,13 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
         output_type = "file"
     elif output_type == "file" and outfile is None:
         raise GMTInvalidInput("""Must specify outfile for ASCII output.""")
-    # Set the default column names for the pandas dataframe header
-    dataframe_header = ["x", "y", "z"]
-    # Set the column names to match an input DataArray as the grid
-    if isinstance(grid, xr.DataArray) and output_type == "pandas":
-        dataframe_header = grid.dims + (grid.name,)
+    if "o" not in kwargs.keys(): # Only set column names for standard output
+        # Set the default column names for the pandas dataframe header
+        dataframe_header = ["x", "y", "z"]
+        # Set the column names to match an input DataArray as the grid
+        if isinstance(grid, xr.DataArray) and output_type == "pandas":
+            # Reverse the dims because it is rows, columns ordered.
+            dataframe_header = (grid.dims[1],) + (grid.dims[0],) + (grid.name,)
 
     with GMTTempFile() as tmpfile:
         with Session() as lib:

From af6aac9593777fbb9675a7ed608e2d698a6375ec Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Wed, 15 Sep 2021 22:50:06 -0400
Subject: [PATCH 41/56] update test

---
 pygmt/tests/test_grd2xyz.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index ab08543658a..07b2380a43f 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -47,7 +47,7 @@ def test_grd2xyz_format(grid):
     assert isinstance(xyz_array, np.ndarray)
     xyz_df = grd2xyz(grid=grid, output_type="pandas")
     assert isinstance(xyz_df, pd.DataFrame)
-    assert list(xyz_df.columns) == ["x", "y", "z"]
+    assert list(xyz_df.columns) == ["lon", "lat", "elevation"]
 
 
 def test_grd2xyz_file_output(grid):

From e1c6555473bc1aa38407ee2219e37bef5b1553fe Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Thu, 16 Sep 2021 18:51:25 -0400
Subject: [PATCH 42/56] Apply suggestions from code review

Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
---
 pygmt/src/grd2xyz.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index d50f970e262..dedd497d143 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -64,7 +64,7 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
     """
     if output_type not in ["numpy", "pandas", "file"]:
         raise GMTInvalidInput(
-            """Must specify format as either numpy, pandas, or file."""
+            "Must specify format as either numpy, pandas, or file."
         )
     if outfile is not None and output_type != "file":
         msg = (
@@ -82,7 +82,7 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
         # Set the column names to match an input DataArray as the grid
         if isinstance(grid, xr.DataArray) and output_type == "pandas":
             # Reverse the dims because it is rows, columns ordered.
-            dataframe_header = (grid.dims[1],) + (grid.dims[0],) + (grid.name,)
+            dataframe_header = [grid.dims[1], grid.dims[0], grid.name]
 
     with GMTTempFile() as tmpfile:
         with Session() as lib:

From 19277951bd8ece0480a18bc2a7ecb2cd102e7d45 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Thu, 16 Sep 2021 18:53:04 -0400
Subject: [PATCH 43/56] add line for grd2xyz region

---
 pygmt/src/grd2xyz.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index d50f970e262..fa4157173d7 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -76,7 +76,7 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
         output_type = "file"
     elif output_type == "file" and outfile is None:
         raise GMTInvalidInput("""Must specify outfile for ASCII output.""")
-    if "o" not in kwargs.keys(): # Only set column names for standard output
+    if "o" not in kwargs.keys():  # Only set column names for standard output
         # Set the default column names for the pandas dataframe header
         dataframe_header = ["x", "y", "z"]
         # Set the column names to match an input DataArray as the grid

From 76190ab81d21647ae0fa7ef30199aa4ddb46528b Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Thu, 16 Sep 2021 18:59:49 -0400
Subject: [PATCH 44/56] update region docstring

---
 pygmt/src/grd2xyz.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 8216011f1f6..498b81e58f2 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -48,6 +48,9 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
     outfile : str
         The file name for the output ASCII file.
     {R}
+        Adding `region` will select a subsection of the grid. If this 
+        subsection exceeds the boundaries of the grid, only the common region 
+        will be output.
     {V}
 
     Returns

From 31388eb885aaecf4ea3fa34d0bf304b2ad3b7a9b Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Thu, 16 Sep 2021 19:02:19 -0400
Subject: [PATCH 45/56] add if statement

---
 pygmt/src/grd2xyz.py | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 498b81e58f2..3298be4362f 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -48,8 +48,8 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
     outfile : str
         The file name for the output ASCII file.
     {R}
-        Adding `region` will select a subsection of the grid. If this 
-        subsection exceeds the boundaries of the grid, only the common region 
+        Adding `region` will select a subsection of the grid. If this
+        subsection exceeds the boundaries of the grid, only the common region
         will be output.
     {V}
 
@@ -66,9 +66,7 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
 
     """
     if output_type not in ["numpy", "pandas", "file"]:
-        raise GMTInvalidInput(
-            "Must specify format as either numpy, pandas, or file."
-        )
+        raise GMTInvalidInput("Must specify format as either numpy, pandas, or file.")
     if outfile is not None and output_type != "file":
         msg = (
             f"Changing `output_type` of grd2xyz from '{output_type}' to 'file' "
@@ -98,9 +96,12 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
 
         # Read temporary csv output to a pandas table
         if outfile == tmpfile.name:  # if user did not set outfile, return pd.DataFrame
-            result = pd.read_csv(
-                tmpfile.name, sep="\t", names=dataframe_header, comment=">"
-            )
+            if "o" not in kwargs.keys():
+                result = pd.read_csv(
+                    tmpfile.name, sep="\t", names=dataframe_header, comment=">"
+                )
+            else:
+                result = pd.read_csv(tmpfile.name, sep="\t", comment=">")
         elif outfile != tmpfile.name:  # return None if outfile set, output in outfile
             result = None
 

From 924a3e01cba0d9220b443621c3a74ffbfff3c8f6 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Sun, 19 Sep 2021 07:26:07 -0400
Subject: [PATCH 46/56] Apply suggestions from code review

Co-authored-by: Wei Ji <23487320+weiji14@users.noreply.github.com>
---
 pygmt/src/grd2xyz.py | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 3298be4362f..add2c5e820c 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -66,21 +66,25 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
 
     """
     if output_type not in ["numpy", "pandas", "file"]:
-        raise GMTInvalidInput("Must specify format as either numpy, pandas, or file.")
+        raise GMTInvalidInput(
+            "Must specify `output_type` either as 'numpy', 'pandas' or 'file'."
+        )
+
     if outfile is not None and output_type != "file":
         msg = (
             f"Changing `output_type` of grd2xyz from '{output_type}' to 'file' "
             "since `outfile` parameter is set. Please use `output_type='file'` "
             "to silence this warning."
         )
-        warnings.warn(msg, category=RuntimeWarning, stacklevel=2)
+        warnings.warn(message=msg, category=RuntimeWarning, stacklevel=2)
         output_type = "file"
-    elif output_type == "file" and outfile is None:
-        raise GMTInvalidInput("""Must specify outfile for ASCII output.""")
-    if "o" not in kwargs.keys():  # Only set column names for standard output
+    elif outfile is None and output_type == "file":
+        raise GMTInvalidInput("Must specify `outfile` for ASCII output.")
+
+    if "o" not in kwargs:  # Only set column names for standard output
         # Set the default column names for the pandas dataframe header
         dataframe_header = ["x", "y", "z"]
-        # Set the column names to match an input DataArray as the grid
+        # Let output pandas column names match input DataArray dimension names
         if isinstance(grid, xr.DataArray) and output_type == "pandas":
             # Reverse the dims because it is rows, columns ordered.
             dataframe_header = [grid.dims[1], grid.dims[0], grid.name]

From 9a3c37736221138173a5217f7431f96c59a35429 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Sun, 19 Sep 2021 19:52:38 -0400
Subject: [PATCH 47/56] update comment for o if statement

---
 pygmt/src/grd2xyz.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index add2c5e820c..f14e51cd0dc 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -81,7 +81,7 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
     elif outfile is None and output_type == "file":
         raise GMTInvalidInput("Must specify `outfile` for ASCII output.")
 
-    if "o" not in kwargs:  # Only set column names for standard output
+    if "o" not in kwargs:  # Set default column names if not specified
         # Set the default column names for the pandas dataframe header
         dataframe_header = ["x", "y", "z"]
         # Let output pandas column names match input DataArray dimension names
@@ -100,7 +100,7 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
 
         # Read temporary csv output to a pandas table
         if outfile == tmpfile.name:  # if user did not set outfile, return pd.DataFrame
-            if "o" not in kwargs.keys():
+            if "o" not in kwargs:
                 result = pd.read_csv(
                     tmpfile.name, sep="\t", names=dataframe_header, comment=">"
                 )

From 4b1214cc92e8ae22040624209ec67a9a66242cbc Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Mon, 20 Sep 2021 15:57:53 -0400
Subject: [PATCH 48/56] change if statement for o

raises GMTInvalidInput if o is specified and the output type is set to "pandas"
---
 pygmt/src/grd2xyz.py | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index f14e51cd0dc..435d37e1cbc 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -81,13 +81,17 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
     elif outfile is None and output_type == "file":
         raise GMTInvalidInput("Must specify `outfile` for ASCII output.")
 
-    if "o" not in kwargs:  # Set default column names if not specified
-        # Set the default column names for the pandas dataframe header
-        dataframe_header = ["x", "y", "z"]
-        # Let output pandas column names match input DataArray dimension names
-        if isinstance(grid, xr.DataArray) and output_type == "pandas":
-            # Reverse the dims because it is rows, columns ordered.
-            dataframe_header = [grid.dims[1], grid.dims[0], grid.name]
+    if "o" in kwargs and output_type == "pandas":
+        raise GMTInvalidInput(
+            "If 'o' is specified, `output_type` must be either as 'numpy' or 'file'."
+        )
+
+    # Set the default column names for the pandas dataframe header
+    dataframe_header = ["x", "y", "z"]
+    # Let output pandas column names match input DataArray dimension names
+    if isinstance(grid, xr.DataArray) and output_type == "pandas":
+        # Reverse the dims because it is rows, columns ordered.
+        dataframe_header = [grid.dims[1], grid.dims[0], grid.name]
 
     with GMTTempFile() as tmpfile:
         with Session() as lib:
@@ -100,12 +104,9 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
 
         # Read temporary csv output to a pandas table
         if outfile == tmpfile.name:  # if user did not set outfile, return pd.DataFrame
-            if "o" not in kwargs:
-                result = pd.read_csv(
-                    tmpfile.name, sep="\t", names=dataframe_header, comment=">"
-                )
-            else:
-                result = pd.read_csv(tmpfile.name, sep="\t", comment=">")
+            result = pd.read_csv(
+                tmpfile.name, sep="\t", names=dataframe_header, comment=">"
+            )
         elif outfile != tmpfile.name:  # return None if outfile set, output in outfile
             result = None
 

From 59bae5c8ecdb1a4ed8363c39ed88aa29c18ae22c Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Mon, 20 Sep 2021 15:58:14 -0400
Subject: [PATCH 49/56] add test for setting o and output_type to pandas

---
 pygmt/tests/test_grd2xyz.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index 07b2380a43f..cee2debcda5 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -86,3 +86,10 @@ def test_grd2xyz_outfile_incorrect_output_type(grid):
             result = grd2xyz(grid=grid, outfile=tmpfile.name, output_type="numpy")
             assert result is None  # return value is None
             assert os.path.exists(path=tmpfile.name)  # check that outfile exists
+
+def test_grd2xyz_pandas_output_wiht_o(grid):
+    """
+    Test that grd2xyz fails when 'o' is set and output_type is set to 'pandas'.
+    """
+    with pytest.raises(GMTInvalidInput):
+        grd2xyz(grid=grid, output_type="pandas", o="2")

From 2a11880c6274a54e21be683702f8565220652f06 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Mon, 20 Sep 2021 16:05:40 -0400
Subject: [PATCH 50/56] run make format

---
 pygmt/tests/test_grd2xyz.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index cee2debcda5..1062a553181 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -87,6 +87,7 @@ def test_grd2xyz_outfile_incorrect_output_type(grid):
             assert result is None  # return value is None
             assert os.path.exists(path=tmpfile.name)  # check that outfile exists
 
+
 def test_grd2xyz_pandas_output_wiht_o(grid):
     """
     Test that grd2xyz fails when 'o' is set and output_type is set to 'pandas'.

From ff45946d09b05ed8ce98c3625d51dced3e614d49 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Mon, 20 Sep 2021 16:06:57 -0400
Subject: [PATCH 51/56] typo fix

---
 pygmt/tests/test_grd2xyz.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index 1062a553181..a209b2263aa 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -88,7 +88,7 @@ def test_grd2xyz_outfile_incorrect_output_type(grid):
             assert os.path.exists(path=tmpfile.name)  # check that outfile exists
 
 
-def test_grd2xyz_pandas_output_wiht_o(grid):
+def test_grd2xyz_pandas_output_with_o(grid):
     """
     Test that grd2xyz fails when 'o' is set and output_type is set to 'pandas'.
     """

From e3336c4ecb7c78a174078825fdf1026b8f97d2da Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Wed, 22 Sep 2021 11:43:39 +0100
Subject: [PATCH 52/56] Apply suggestions from code review

Co-authored-by: Wei Ji <23487320+weiji14@users.noreply.github.com>
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
---
 pygmt/src/grd2xyz.py | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 435d37e1cbc..0985e117dac 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -20,8 +20,9 @@
 @use_alias(
     R="region",
     V="verbose",
+    o="outcols",
 )
-@kwargs_to_strings(R="sequence")
+@kwargs_to_strings(R="sequence", o="sequence_comma")
 def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
     r"""
     Convert grid to data table.
@@ -48,10 +49,11 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
     outfile : str
         The file name for the output ASCII file.
     {R}
-        Adding `region` will select a subsection of the grid. If this
+        Adding ``region`` will select a subsection of the grid. If this
         subsection exceeds the boundaries of the grid, only the common region
         will be output.
     {V}
+    {o}
 
     Returns
     -------
@@ -67,7 +69,7 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
     """
     if output_type not in ["numpy", "pandas", "file"]:
         raise GMTInvalidInput(
-            "Must specify `output_type` either as 'numpy', 'pandas' or 'file'."
+            "Must specify 'output_type' either as 'numpy', 'pandas' or 'file'."
         )
 
     if outfile is not None and output_type != "file":
@@ -83,7 +85,8 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
 
     if "o" in kwargs and output_type == "pandas":
         raise GMTInvalidInput(
-            "If 'o' is specified, `output_type` must be either as 'numpy' or 'file'."
+            "If 'outcols' is specified, `output_type` must be either 'numpy'"
+            "or 'file'."
         )
 
     # Set the default column names for the pandas dataframe header

From 552bf3f0a79cf136d0deab120f830ce3d394820d Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Wed, 22 Sep 2021 12:23:08 +0100
Subject: [PATCH 53/56] Apply suggestions from code review

Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
---
 pygmt/src/grd2xyz.py        | 8 ++++----
 pygmt/tests/test_grd2xyz.py | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 0985e117dac..22f334ad354 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -74,18 +74,18 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
 
     if outfile is not None and output_type != "file":
         msg = (
-            f"Changing `output_type` of grd2xyz from '{output_type}' to 'file' "
-            "since `outfile` parameter is set. Please use `output_type='file'` "
+            f"Changing 'output_type' of grd2xyz from '{output_type}' to 'file' "
+            "since 'outfile' parameter is set. Please use output_type='file' "
             "to silence this warning."
         )
         warnings.warn(message=msg, category=RuntimeWarning, stacklevel=2)
         output_type = "file"
     elif outfile is None and output_type == "file":
-        raise GMTInvalidInput("Must specify `outfile` for ASCII output.")
+        raise GMTInvalidInput("Must specify 'outfile' for ASCII output.")
 
     if "o" in kwargs and output_type == "pandas":
         raise GMTInvalidInput(
-            "If 'outcols' is specified, `output_type` must be either 'numpy'"
+            "If 'outcols' is specified, 'output_type' must be either 'numpy'"
             "or 'file'."
         )
 
diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index a209b2263aa..654c053aaea 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -90,7 +90,7 @@ def test_grd2xyz_outfile_incorrect_output_type(grid):
 
 def test_grd2xyz_pandas_output_with_o(grid):
     """
-    Test that grd2xyz fails when 'o' is set and output_type is set to 'pandas'.
+    Test that grd2xyz fails when outcols is set and output_type is set to 'pandas'.
     """
     with pytest.raises(GMTInvalidInput):
-        grd2xyz(grid=grid, output_type="pandas", o="2")
+        grd2xyz(grid=grid, output_type="pandas", outcols="2")

From 6731814075e1640f841a7b722ba4c9201c29f17c Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Wed, 22 Sep 2021 12:34:01 +0100
Subject: [PATCH 54/56] Update pygmt/src/grd2xyz.py

Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
---
 pygmt/src/grd2xyz.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/pygmt/src/grd2xyz.py b/pygmt/src/grd2xyz.py
index 22f334ad354..c6404febf63 100644
--- a/pygmt/src/grd2xyz.py
+++ b/pygmt/src/grd2xyz.py
@@ -63,8 +63,7 @@ def grd2xyz(grid, output_type="pandas", outfile=None, **kwargs):
         - None if ``outfile`` is set (output will be stored in file set by
           ``outfile``)
         - :class:`pandas.DataFrame` or :class:`numpy.ndarray` if ``outfile`` is
-          not set (depends on ``output_type`` [Default is
-          :class:`pandas.DataFrame`])
+          not set (depends on ``output_type``)
 
     """
     if output_type not in ["numpy", "pandas", "file"]:

From f49dac07f6a9a1cb1940c3fdafc06c5f355aba69 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Wed, 22 Sep 2021 12:40:54 +0100
Subject: [PATCH 55/56] fix sentence in docstring

---
 pygmt/tests/test_grd2xyz.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index 654c053aaea..7efaff0297a 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -78,8 +78,8 @@ def test_grd2xyz_no_outfile(grid):
 
 def test_grd2xyz_outfile_incorrect_output_type(grid):
     """
-    Test that grd2xyz raises a warning when an outfile name is set but the
-    output_type is not set to file is set with no outfile.
+    Test that grd2xyz raises a warning when an outfile filename is set but the
+    output_type is not set to 'file'.
     """
     with pytest.warns(RuntimeWarning):
         with GMTTempFile(suffix=".xyz") as tmpfile:

From 708e3c42a31c88e0142b0ff68f8d72d209c50442 Mon Sep 17 00:00:00 2001
From: Will Schlitzer <schlitzer90@gmail.com>
Date: Wed, 22 Sep 2021 13:12:48 +0100
Subject: [PATCH 56/56] run make format

---
 pygmt/tests/test_grd2xyz.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pygmt/tests/test_grd2xyz.py b/pygmt/tests/test_grd2xyz.py
index 7efaff0297a..230132dc548 100644
--- a/pygmt/tests/test_grd2xyz.py
+++ b/pygmt/tests/test_grd2xyz.py
@@ -90,7 +90,8 @@ def test_grd2xyz_outfile_incorrect_output_type(grid):
 
 def test_grd2xyz_pandas_output_with_o(grid):
     """
-    Test that grd2xyz fails when outcols is set and output_type is set to 'pandas'.
+    Test that grd2xyz fails when outcols is set and output_type is set to
+    'pandas'.
     """
     with pytest.raises(GMTInvalidInput):
         grd2xyz(grid=grid, output_type="pandas", outcols="2")