ENH: Add axis argument to Dataframe.corr

pandas/core/frame.py

@@ -8116,9 +8116,14 @@ def _series_round(s, decimals):
     # ----------------------------------------------------------------------
     # Statistical methods, etc.
 
-    def corr(self, method="pearson", min_periods=1) -> "DataFrame":
+    def corr(self, method="pearson", min_periods=1, axis=0) -> "DataFrame":
         """
-        Compute pairwise correlation of columns, excluding NA/null values.
+        Compute pairwise correlation of rows or columns, excluding NA/null values.
+
+        Pairwise correlation is computed between rows or columns of
+        a DataFrame. Returned Dataframe is a Correlation matrix between
+        pairwise rows or columns. Both NA and null values are automatically
+        excluded from the calculation.
 
         Parameters
         ----------
@@ -8140,6 +8145,10 @@ def corr(self, method="pearson", min_periods=1) -> "DataFrame":
             to have a valid result. Currently only available for Pearson
             and Spearman correlation.
 
+        axis : {0 or 'index', 1 or 'columns'}, default 0
+            The axis to use. 0 or 'index' to compute column-wise, 1 or 'columns' for
+            row-wise.
+
         Returns
         -------
         DataFrame
@@ -8162,12 +8171,20 @@ def corr(self, method="pearson", min_periods=1) -> "DataFrame":
               dogs  cats
         dogs   1.0   0.3
         cats   0.3   1.0
+        >>> df.T.corr(method=histogram_intersection, axis=1)
+              dogs  cats
+        dogs   1.0   0.3
+        cats   0.3   1.0
         """
         numeric_df = self._get_numeric_data()
-        cols = numeric_df.columns
+        axis = numeric_df._get_axis_number(axis)
+        cols = numeric_df._get_agg_axis(axis)
         idx = cols.copy()
         mat = numeric_df.to_numpy(dtype=float, na_value=np.nan, copy=False)
 
+        if axis == 1:
+            mat = mat.transpose()
+
         if method == "pearson":
             correl = libalgos.nancorr(mat, minp=min_periods)
         elif method == "spearman":

pandas/tests/frame/methods/test_cov_corr.py

@@ -175,6 +175,13 @@ def test_corr_int(self):
         df3.cov()
         df3.corr()
 
+    @td.skip_if_no_scipy
+    def test_corr_axes(self):
+        # https://github.com/pandas-dev/pandas/issues/35002
+        df = pd.DataFrame(np.random.normal(size=(10, 2)))
+        for meth in ["pearson", "kendall", "spearman"]:
+            tm.assert_frame_equal(df.T.corr(meth, axis=1), df.corr(meth, axis=0))
+
     @td.skip_if_no_scipy
     @pytest.mark.parametrize(
         "nullable_column", [pd.array([1, 2, 3]), pd.array([1, 2, None])]