From 5e4064c7d732703a27f9dc1bc8f207f91747c9a1 Mon Sep 17 00:00:00 2001
From: Vyas Ramasubramani <vyasr@nvidia.com>
Date: Wed, 5 May 2021 11:48:49 -0700
Subject: [PATCH 1/9] Move monotonicity methods to SingleColumnFrame.

---
 python/cudf/cudf/core/frame.py  | 32 ++++++++++++++++++++++++++++++++
 python/cudf/cudf/core/index.py  | 25 +------------------------
 python/cudf/cudf/core/series.py | 33 ---------------------------------
 3 files changed, 33 insertions(+), 57 deletions(-)

diff --git a/python/cudf/cudf/core/frame.py b/python/cudf/cudf/core/frame.py
index 25552009444..86e331048dd 100644
--- a/python/cudf/cudf/core/frame.py
+++ b/python/cudf/cudf/core/frame.py
@@ -3529,6 +3529,38 @@ def to_arrow(self):
         """
         return self._column.to_arrow()
 
+    @property
+    def is_monotonic(self):
+        """Return boolean if values in the object are monotonic_increasing.
+
+        This property is an alias for :attr:`is_monotonic_increasing`.
+
+        Returns
+        -------
+        bool
+        """
+        return self.is_monotonic_increasing
+
+    @property
+    def is_monotonic_increasing(self):
+        """Return boolean if values in the object are monotonic_increasing.
+
+        Returns
+        -------
+        bool
+        """
+        return self._column.is_monotonic_increasing
+
+    @property
+    def is_monotonic_decreasing(self):
+        """Return boolean if values in the object are monotonic_decreasing.
+
+        Returns
+        -------
+        bool
+        """
+        return self._column.is_monotonic_decreasing
+
     @property
     def _copy_construct_defaults(self):
         """A default dictionary of kwargs to be used for copy construction."""
diff --git a/python/cudf/cudf/core/index.py b/python/cudf/cudf/core/index.py
index 2846dc241db..db595dfe63c 100644
--- a/python/cudf/cudf/core/index.py
+++ b/python/cudf/cudf/core/index.py
@@ -1148,30 +1148,7 @@ def is_unique(self):
         """
         Return if the index has unique values.
         """
-        raise (NotImplementedError)
-
-    @property
-    def is_monotonic(self):
-        """
-        Alias for is_monotonic_increasing.
-        """
-        return self.is_monotonic_increasing
-
-    @property
-    def is_monotonic_increasing(self):
-        """
-        Return if the index is monotonic increasing
-        (only equal or increasing) values.
-        """
-        return self._values.is_monotonic_increasing
-
-    @property
-    def is_monotonic_decreasing(self):
-        """
-        Return if the index is monotonic decreasing
-        (only equal or decreasing) values.
-        """
-        return self._values.is_monotonic_decreasing
+        raise NotImplementedError
 
     @property
     def empty(self):
diff --git a/python/cudf/cudf/core/series.py b/python/cudf/cudf/core/series.py
index 7b1e6454394..385f50c75fa 100644
--- a/python/cudf/cudf/core/series.py
+++ b/python/cudf/cudf/core/series.py
@@ -5945,39 +5945,6 @@ def is_unique(self):
         """
         return self._column.is_unique
 
-    @property
-    def is_monotonic(self):
-        """
-        Return boolean if values in the object are monotonic_increasing.
-
-        Returns
-        -------
-        out : bool
-        """
-        return self._column.is_monotonic_increasing
-
-    @property
-    def is_monotonic_increasing(self):
-        """
-        Return boolean if values in the object are monotonic_increasing.
-
-        Returns
-        -------
-        out : bool
-        """
-        return self._column.is_monotonic_increasing
-
-    @property
-    def is_monotonic_decreasing(self):
-        """
-        Return boolean if values in the object are monotonic_decreasing.
-
-        Returns
-        -------
-        out : bool
-        """
-        return self._column.is_monotonic_decreasing
-
     @property
     def __cuda_array_interface__(self):
         return self._column.__cuda_array_interface__

From b75842f60052b0b15f52ae627c5f731523240d08 Mon Sep 17 00:00:00 2001
From: Vyas Ramasubramani <vyasr@nvidia.com>
Date: Wed, 5 May 2021 11:53:22 -0700
Subject: [PATCH 2/9] Move is_unique to SingleColumnFrame.

---
 python/cudf/cudf/core/frame.py  | 10 ++++++++++
 python/cudf/cudf/core/index.py  | 14 --------------
 python/cudf/cudf/core/series.py | 11 -----------
 3 files changed, 10 insertions(+), 25 deletions(-)

diff --git a/python/cudf/cudf/core/frame.py b/python/cudf/cudf/core/frame.py
index 86e331048dd..a098525000c 100644
--- a/python/cudf/cudf/core/frame.py
+++ b/python/cudf/cudf/core/frame.py
@@ -3529,6 +3529,16 @@ def to_arrow(self):
         """
         return self._column.to_arrow()
 
+    @property
+    def is_unique(self):
+        """Return boolean if values in the object are unique.
+
+        Returns
+        -------
+        bool
+        """
+        return self._column.is_unique
+
     @property
     def is_monotonic(self):
         """Return boolean if values in the object are monotonic_increasing.
diff --git a/python/cudf/cudf/core/index.py b/python/cudf/cudf/core/index.py
index db595dfe63c..b0193308c22 100644
--- a/python/cudf/cudf/core/index.py
+++ b/python/cudf/cudf/core/index.py
@@ -1143,13 +1143,6 @@ def to_series(self, index=None, name=None):
             name=self.name if name is None else name,
         )
 
-    @property
-    def is_unique(self):
-        """
-        Return if the index has unique values.
-        """
-        raise NotImplementedError
-
     @property
     def empty(self):
         """
@@ -1966,13 +1959,6 @@ def find_label_range(self, first, last):
             end += 1
         return begin, end
 
-    @property
-    def is_unique(self):
-        """
-        Return if the index has unique values.
-        """
-        return self._values.is_unique
-
     def get_slice_bound(self, label, side, kind):
         return self._values.get_slice_bound(label, side, kind)
 
diff --git a/python/cudf/cudf/core/series.py b/python/cudf/cudf/core/series.py
index 385f50c75fa..aaac970820b 100644
--- a/python/cudf/cudf/core/series.py
+++ b/python/cudf/cudf/core/series.py
@@ -5934,17 +5934,6 @@ def rename(self, index=None, copy=True):
 
         return out.copy(deep=copy)
 
-    @property
-    def is_unique(self):
-        """
-        Return boolean if values in the object are unique.
-
-        Returns
-        -------
-        out : bool
-        """
-        return self._column.is_unique
-
     @property
     def __cuda_array_interface__(self):
         return self._column.__cuda_array_interface__

From 7d7aac969e780cbdd2f61feb04183ed6dd9378ce Mon Sep 17 00:00:00 2001
From: Vyas Ramasubramani <vyasr@nvidia.com>
Date: Wed, 5 May 2021 11:57:19 -0700
Subject: [PATCH 3/9] Move __cuda_array_interface__ to SingleColumnFrame.

---
 python/cudf/cudf/core/frame.py  |  4 ++++
 python/cudf/cudf/core/index.py  | 14 +-------------
 python/cudf/cudf/core/series.py |  4 ----
 3 files changed, 5 insertions(+), 17 deletions(-)

diff --git a/python/cudf/cudf/core/frame.py b/python/cudf/cudf/core/frame.py
index a098525000c..5a92fe7e597 100644
--- a/python/cudf/cudf/core/frame.py
+++ b/python/cudf/cudf/core/frame.py
@@ -3571,6 +3571,10 @@ def is_monotonic_decreasing(self):
         """
         return self._column.is_monotonic_decreasing
 
+    @property
+    def __cuda_array_interface__(self):
+        return self._column.__cuda_array_interface__
+
     @property
     def _copy_construct_defaults(self):
         """A default dictionary of kwargs to be used for copy construction."""
diff --git a/python/cudf/cudf/core/index.py b/python/cudf/cudf/core/index.py
index b0193308c22..ac8b5a9ca9e 100644
--- a/python/cudf/cudf/core/index.py
+++ b/python/cudf/cudf/core/index.py
@@ -1281,10 +1281,6 @@ def where(self, cond, other=None):
         """
         return super().where(cond=cond, other=other)
 
-    @property
-    def __cuda_array_interface__(self):
-        raise (NotImplementedError)
-
     def memory_usage(self, deep=False):
         """
         Memory usage of the values.
@@ -1742,10 +1738,6 @@ def get_slice_bound(self, label, side, kind=None):
         pos = search_range(start, stop, label, step, side=side)
         return pos
 
-    @property
-    def __cuda_array_interface__(self):
-        return self._values.__cuda_array_interface__
-
     def memory_usage(self, **kwargs):
         return 0
 
@@ -1807,7 +1799,7 @@ def _initialize(self, values, **kwargs):
 
     @property
     def _values(self):
-        return next(iter(self._data.columns))
+        return self._column
 
     def copy(self, name=None, deep=False, dtype=None, names=None):
         """
@@ -1962,10 +1954,6 @@ def find_label_range(self, first, last):
     def get_slice_bound(self, label, side, kind):
         return self._values.get_slice_bound(label, side, kind)
 
-    @property
-    def __cuda_array_interface__(self):
-        return self._values.__cuda_array_interface__
-
 
 class NumericIndex(GenericIndex):
     """Immutable, ordered and sliceable sequence of labels.
diff --git a/python/cudf/cudf/core/series.py b/python/cudf/cudf/core/series.py
index aaac970820b..16cb8512365 100644
--- a/python/cudf/cudf/core/series.py
+++ b/python/cudf/cudf/core/series.py
@@ -5934,10 +5934,6 @@ def rename(self, index=None, copy=True):
 
         return out.copy(deep=copy)
 
-    @property
-    def __cuda_array_interface__(self):
-        return self._column.__cuda_array_interface__
-
     def _align_to_index(
         self, index, how="outer", sort=True, allow_non_unique=False
     ):

From f3bcb1062a3d875d5cbb62b1227c0c2fec483344 Mon Sep 17 00:00:00 2001
From: Vyas Ramasubramani <vyasr@nvidia.com>
Date: Wed, 5 May 2021 12:01:22 -0700
Subject: [PATCH 4/9] Move factorize to SingleColumnFrame.

---
 python/cudf/cudf/core/frame.py  | 27 +++++++++++++++++++++++++++
 python/cudf/cudf/core/index.py  | 11 -----------
 python/cudf/cudf/core/series.py | 26 --------------------------
 3 files changed, 27 insertions(+), 37 deletions(-)

diff --git a/python/cudf/cudf/core/frame.py b/python/cudf/cudf/core/frame.py
index 5a92fe7e597..f092a6f05c0 100644
--- a/python/cudf/cudf/core/frame.py
+++ b/python/cudf/cudf/core/frame.py
@@ -3575,6 +3575,33 @@ def is_monotonic_decreasing(self):
     def __cuda_array_interface__(self):
         return self._column.__cuda_array_interface__
 
+    def factorize(self, na_sentinel=-1):
+        """Encode the input values as integer labels
+
+        Parameters
+        ----------
+        na_sentinel : number
+            Value to indicate missing category.
+
+        Returns
+        --------
+        (labels, cats) : (cupy.ndarray, cupy.ndarray or Index)
+            - *labels* contains the encoded values
+            - *cats* contains the categories in order that the N-th
+              item corresponds to the (N-1) code.
+
+        Examples
+        --------
+        >>> import cudf
+        >>> s = cudf.Series(['a', 'a', 'c'])
+        >>> codes, uniques = s.factorize()
+        >>> codes
+        array([0, 0, 1], dtype=int8)
+        >>> uniques
+        StringIndex(['a' 'c'], dtype='object')
+        """
+        return cudf.core.algorithms.factorize(self, na_sentinel=na_sentinel)
+
     @property
     def _copy_construct_defaults(self):
         """A default dictionary of kwargs to be used for copy construction."""
diff --git a/python/cudf/cudf/core/index.py b/python/cudf/cudf/core/index.py
index ac8b5a9ca9e..3972238e898 100644
--- a/python/cudf/cudf/core/index.py
+++ b/python/cudf/cudf/core/index.py
@@ -335,17 +335,6 @@ def _clean_nulls_from_index(self):
         else:
             return self
 
-    def factorize(self, na_sentinel=-1):
-        """
-        Encode the input values as integer labels
-
-        See Also
-        --------
-        cudf.core.series.Series.factorize : Encode the input values of Series.
-
-        """
-        return cudf.core.algorithms.factorize(self, na_sentinel=na_sentinel)
-
     @property
     def nlevels(self):
         """
diff --git a/python/cudf/cudf/core/series.py b/python/cudf/cudf/core/series.py
index 16cb8512365..0ca6454f49c 100644
--- a/python/cudf/cudf/core/series.py
+++ b/python/cudf/cudf/core/series.py
@@ -3860,32 +3860,6 @@ def _return_sentinel_series():
 
         return codes._copy_construct(name=None, index=self.index)
 
-    def factorize(self, na_sentinel=-1):
-        """Encode the input values as integer labels
-
-        Parameters
-        ----------
-        na_sentinel : number
-            Value to indicate missing category.
-
-        Returns
-        --------
-        (labels, cats) : (cupy.ndarray, cupy.ndarray or Index)
-            - *labels* contains the encoded values
-            - *cats* contains the categories in order that the N-th
-              item corresponds to the (N-1) code.
-
-        Examples
-        --------
-        >>> import cudf
-        >>> s = cudf.Series(['a', 'a', 'c'])
-        >>> codes
-        array([0, 0, 1], dtype=int8)
-        >>> uniques
-        StringIndex(['a' 'c'], dtype='object')
-        """
-        return cudf.core.algorithms.factorize(self, na_sentinel=na_sentinel)
-
     # UDF related
 
     def applymap(self, udf, out_dtype=None):

From 6baa63e227bb5b554a0f9639aa6706f15132ee77 Mon Sep 17 00:00:00 2001
From: Vyas Ramasubramani <vyasr@nvidia.com>
Date: Fri, 14 May 2021 12:06:44 -0700
Subject: [PATCH 5/9] Alias product as prod rather than redefining.

---
 python/cudf/cudf/core/series.py | 55 +--------------------------------
 1 file changed, 1 insertion(+), 54 deletions(-)

diff --git a/python/cudf/cudf/core/series.py b/python/cudf/cudf/core/series.py
index 0ca6454f49c..d9685521c63 100644
--- a/python/cudf/cudf/core/series.py
+++ b/python/cudf/cudf/core/series.py
@@ -4227,60 +4227,7 @@ def product(
             skipna=skipna, dtype=dtype, min_count=min_count
         )
 
-    def prod(
-        self,
-        axis=None,
-        skipna=None,
-        dtype=None,
-        level=None,
-        numeric_only=None,
-        min_count=0,
-        **kwargs,
-    ):
-        """
-        Return product of the values in the series
-
-        Parameters
-        ----------
-
-        skipna : bool, default True
-            Exclude NA/null values when computing the result.
-
-        dtype : data type
-            Data type to cast the result to.
-
-        min_count : int, default 0
-            The required number of valid values to perform the operation.
-            If fewer than min_count non-NA values are present the result
-            will be NA.
-
-            The default being 0. This means the sum of an all-NA or empty
-            Series is 0, and the product of an all-NA or empty Series is 1.
-
-        Returns
-        -------
-        scalar
-
-        Notes
-        -----
-        Parameters currently not supported are `axis`, `level`, `numeric_only`.
-
-        Examples
-        --------
-        >>> import cudf
-        >>> ser = cudf.Series([1, 5, 2, 4, 3])
-        >>> ser.prod()
-        120
-        """
-        return self.product(
-            axis=axis,
-            skipna=skipna,
-            dtype=dtype,
-            level=level,
-            numeric_only=numeric_only,
-            min_count=min_count,
-            **kwargs,
-        )
+    prod = product
 
     def cummin(self, axis=None, skipna=True, *args, **kwargs):
         """

From c1ff6ae51949f84d8879b517d2844756eedf4f47 Mon Sep 17 00:00:00 2001
From: Vyas Ramasubramani <vyasr@nvidia.com>
Date: Fri, 14 May 2021 12:26:42 -0700
Subject: [PATCH 6/9] Delete more redundant properties and make _num_columns a
 constant time op for SingleColumnFrame.

---
 python/cudf/cudf/core/frame.py |  6 +++-
 python/cudf/cudf/core/index.py | 57 ----------------------------------
 2 files changed, 5 insertions(+), 58 deletions(-)

diff --git a/python/cudf/cudf/core/frame.py b/python/cudf/cudf/core/frame.py
index f092a6f05c0..f59954aaf08 100644
--- a/python/cudf/cudf/core/frame.py
+++ b/python/cudf/cudf/core/frame.py
@@ -28,8 +28,8 @@
 from cudf.utils.dtypes import (
     is_categorical_dtype,
     is_column_like,
-    is_numerical_dtype,
     is_decimal_dtype,
+    is_numerical_dtype,
     is_scalar,
     min_scalar_type,
 )
@@ -3364,6 +3364,10 @@ def __bool__(self):
             "a.empty, a.bool(), a.item(), a.any() or a.all()."
         )
 
+    @property
+    def _num_columns(self):
+        return 1
+
     @property
     def _column(self):
         return self._data[self.name]
diff --git a/python/cudf/cudf/core/index.py b/python/cudf/cudf/core/index.py
index 3972238e898..a7d5013c70f 100644
--- a/python/cudf/cudf/core/index.py
+++ b/python/cudf/cudf/core/index.py
@@ -1132,29 +1132,6 @@ def to_series(self, index=None, name=None):
             name=self.name if name is None else name,
         )
 
-    @property
-    def empty(self):
-        """
-        Indicator whether Index is empty.
-
-        True if Index is entirely empty (no items).
-
-        Returns
-        -------
-        out : bool
-            If Index is empty, return True, if not return False.
-
-        Examples
-        --------
-        >>> import cudf
-        >>> index = cudf.Index([])
-        >>> index
-        Float64Index([], dtype='float64')
-        >>> index.empty
-        True
-        """
-        return not self.size
-
     def get_slice_bound(self, label, side, kind):
         """
         Calculate slice bound that corresponds to given label.
@@ -1240,36 +1217,6 @@ def isin(self, values):
 
         return result
 
-    def where(self, cond, other=None):
-        """
-        Replace values where the condition is False.
-
-        Parameters
-        ----------
-        cond : bool array-like with the same length as self
-            Where cond is True, keep the original value.
-            Where False, replace with corresponding value from other.
-            Callables are not supported.
-        other: scalar, or array-like
-            Entries where cond is False are replaced with
-            corresponding value from other. Callables are not
-            supported. Default is None.
-
-        Returns
-        -------
-        Same type as caller
-
-        Examples
-        --------
-        >>> import cudf
-        >>> index = cudf.Index([4, 3, 2, 1, 0])
-        >>> index
-        Int64Index([4, 3, 2, 1, 0], dtype='int64')
-        >>> index.where(index > 2, 15)
-        Int64Index([4, 3, 15, 15, 15], dtype='int64')
-        """
-        return super().where(cond=cond, other=other)
-
     def memory_usage(self, deep=False):
         """
         Memory usage of the values.
@@ -1462,10 +1409,6 @@ def step(self):
         """
         return self._step
 
-    @property
-    def _num_columns(self):
-        return 1
-
     @property
     def _num_rows(self):
         return len(self)

From 7aa9c4c689eba5bb8034bdb7b5ceea9ccebadc93 Mon Sep 17 00:00:00 2001
From: Vyas Ramasubramani <vyasr@nvidia.com>
Date: Fri, 14 May 2021 12:32:09 -0700
Subject: [PATCH 7/9] Simplify implementation of isin for Index.

---
 python/cudf/cudf/core/index.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/python/cudf/cudf/core/index.py b/python/cudf/cudf/core/index.py
index a7d5013c70f..bc5900999ae 100644
--- a/python/cudf/cudf/core/index.py
+++ b/python/cudf/cudf/core/index.py
@@ -1213,9 +1213,7 @@ def isin(self, values):
         array([ True, False, False])
         """
 
-        result = self.to_series().isin(values).values
-
-        return result
+        return self._values.isin(values).values
 
     def memory_usage(self, deep=False):
         """

From 2e847c7f5039a258d077c5ea5ef3611ad4b33c1b Mon Sep 17 00:00:00 2001
From: Vyas Ramasubramani <vyasr@nvidia.com>
Date: Fri, 14 May 2021 12:47:01 -0700
Subject: [PATCH 8/9] Fix _num_columns for MultiIndex.

---
 python/cudf/cudf/core/multiindex.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/python/cudf/cudf/core/multiindex.py b/python/cudf/cudf/core/multiindex.py
index ca029198e52..e0a895f28cc 100644
--- a/python/cudf/cudf/core/multiindex.py
+++ b/python/cudf/cudf/core/multiindex.py
@@ -204,6 +204,11 @@ def names(self, value):
             )
         self._names = pd.core.indexes.frozen.FrozenList(value)
 
+    @property
+    def _num_columns(self):
+        # MultiIndex is not a single-columned frame.
+        return super(SingleColumnFrame, self)._num_columns
+
     def rename(self, names, inplace=False):
         """
         Alter MultiIndex level names

From ea9331f4def10b5394cb60bbbfc28da7e7fb00de Mon Sep 17 00:00:00 2001
From: Vyas Ramasubramani <vyasr@nvidia.com>
Date: Fri, 14 May 2021 12:58:52 -0700
Subject: [PATCH 9/9] Put back where since it's there to remove the inplace
 parameter.

---
 python/cudf/cudf/core/index.py | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/python/cudf/cudf/core/index.py b/python/cudf/cudf/core/index.py
index bc5900999ae..94ddeb72028 100644
--- a/python/cudf/cudf/core/index.py
+++ b/python/cudf/cudf/core/index.py
@@ -1215,6 +1215,36 @@ def isin(self, values):
 
         return self._values.isin(values).values
 
+    def where(self, cond, other=None):
+        """
+        Replace values where the condition is False.
+
+        Parameters
+        ----------
+        cond : bool array-like with the same length as self
+            Where cond is True, keep the original value.
+            Where False, replace with corresponding value from other.
+            Callables are not supported.
+        other: scalar, or array-like
+            Entries where cond is False are replaced with
+            corresponding value from other. Callables are not
+            supported. Default is None.
+
+        Returns
+        -------
+        Same type as caller
+
+        Examples
+        --------
+        >>> import cudf
+        >>> index = cudf.Index([4, 3, 2, 1, 0])
+        >>> index
+        Int64Index([4, 3, 2, 1, 0], dtype='int64')
+        >>> index.where(index > 2, 15)
+        Int64Index([4, 3, 15, 15, 15], dtype='int64')
+        """
+        return super().where(cond=cond, other=other)
+
     def memory_usage(self, deep=False):
         """
         Memory usage of the values.