Put checks for unequal sized lists near top and add some unit tests

pygmt/src/meca.py

@@ -240,6 +240,29 @@ def update_pointers(data_pointers):
         ):
             raise GMTError("Location not fully specified.")
 
+        # check the inputs for longitude, latitude, and depth
+        # just in case the user entered different length lists
+        if (
+            isinstance(longitude, (list, np.ndarray))
+            or isinstance(latitude, (list, np.ndarray))
+            or isinstance(depth, (list, np.ndarray))
+        ):
+            if (len(longitude) != len(latitude)) or (len(longitude) != len(depth)):
+                raise GMTError("Unequal number of focal mechanism locations supplied.")
+
+        if isinstance(spec, dict) and any(
+            isinstance(s, (list, np.ndarray)) for s in spec.values()
+        ):
+            # before constructing the 2D array lets check that each key
+            # of the dict has the same quantity of values to avoid bugs
+            list_length = len(list(spec.values())[0])
+            for value in list(spec.values()):
+                if len(value) != list_length:
+                    raise GMTError(
+                        "Unequal number of focal mechanism "
+                        "parameters supplied in 'spec'."
+                    )
+
         param_conventions = {
             "AKI": ["strike", "dip", "rake", "magnitude"],
             "GCMT": ["strike1", "dip1", "dip2", "rake2", "mantissa", "exponent"],

pygmt/tests/test_meca.py

@@ -7,6 +7,7 @@
 import pandas as pd
 import pytest
 from pygmt import Figure
+from pygmt.exceptions import GMTError
 from pygmt.helpers import GMTTempFile
 
 TEST_DATA_DIR = os.path.join(os.path.dirname(__file__), "data")
@@ -56,6 +57,39 @@ def test_meca_spec_dict_list():
     return fig
 
 
+def test_meca_spec_unequal_sized_lists_fails():
+    """
+    Test that supplying a dictionary containing unequal sized lists of
+    coordinates (longitude/latitude/depth) or focal mechanisms
+    (strike/dip/rake/magnitude) to the spec parameter fails.
+    """
+    fig = Figure()
+
+    # Unequal sized coordinates (longitude/latitude/depth)
+    focal_mechanisms = dict(
+        strike=[330, 350], dip=[30, 50], rake=[90, 90], magnitude=[3, 2]
+    )
+    with pytest.raises(GMTError):
+        fig.meca(
+            spec=focal_mechanisms,
+            longitude=[-124.3],
+            latitude=[48.1, 48.2],
+            depth=[12.0],
+            scale="2c",
+        )
+
+    # Unequal sized focal mechanisms (strike/dip/rake/magnitude)
+    focal_mechanisms = dict(strike=[330], dip=[30, 50], rake=[90], magnitude=[3, 2])
+    with pytest.raises(GMTError):
+        fig.meca(
+            spec=focal_mechanisms,
+            longitude=[-124.3, -124.4],
+            latitude=[48.1, 48.2],
+            depth=[12.0, 11.0],
+            scale="2c",
+        )
+
+
 @pytest.mark.mpl_image_compare
 def test_meca_spec_dataframe():
     """