BUG: addresses #14855 by fixing color kwarg conflict

 - [x] closes #14855    - [x] tests passed   - [x] passes ``git diff
upstream/master | flake8 --diff``

Author: alexandercbooth <[email protected]>

This patch had conflicts when merged, resolved by
Committer: Tom Augspurger <[email protected]>

Closes #14871 from alexandercbooth/fix-color-scatterm-bug and squashes the following commits:

3245f09 [alexandercbooth] DOC: moving whatsnew entry to 0.20.0
8ff5f51 [alexandercbooth] BUG: addresses #14855 by fixing color kwarg conflict

Author: alexandercbooth

doc/source/whatsnew/v0.20.0.txt

@@ -1056,6 +1056,7 @@ Plotting
 
 - Bug in ``DataFrame.hist`` where ``plt.tight_layout`` caused an ``AttributeError``  (use ``matplotlib >= 2.0.1``) (:issue:`9351`)
 - Bug in ``DataFrame.boxplot`` where ``fontsize`` was not applied to the tick labels on both axes (:issue:`15108`)
+- Bug in ``pd.scatter_matrix()`` could accept either ``color`` or ``c``, but not both (:issue:`14855`)
 
 Groupby/Resample/Rolling
 ^^^^^^^^^^^^^^^^^^^^^^^^

pandas/tests/plotting/test_misc.py

@@ -76,6 +76,12 @@ def scat(**kwds):
             _check_plot_works(scat, diagonal='hist')
         with tm.assert_produces_warning(UserWarning):
             _check_plot_works(scat, range_padding=.1)
+        with tm.assert_produces_warning(UserWarning):
+            _check_plot_works(scat, color='rgb')
+        with tm.assert_produces_warning(UserWarning):
+            _check_plot_works(scat, c='rgb')
+        with tm.assert_produces_warning(UserWarning):
+            _check_plot_works(scat, facecolor='rgb')
 
         def scat2(x, y, by=None, ax=None, figsize=None):
             return plotting.scatter_plot(df, x, y, by, ax, figsize=None)

pandas/tools/plotting.py

@@ -349,7 +349,6 @@ def scatter_matrix(frame, alpha=0.5, figsize=None, ax=None, grid=False,
     >>> df = DataFrame(np.random.randn(1000, 4), columns=['A','B','C','D'])
     >>> scatter_matrix(df, alpha=0.2)
     """
-    import matplotlib.pyplot as plt
 
     df = frame._get_numeric_data()
     n = df.columns.size
@@ -367,8 +366,8 @@ def scatter_matrix(frame, alpha=0.5, figsize=None, ax=None, grid=False,
     hist_kwds = hist_kwds or {}
     density_kwds = density_kwds or {}
 
-    # workaround because `c='b'` is hardcoded in matplotlibs scatter method
-    kwds.setdefault('c', plt.rcParams['patch.facecolor'])
+    # GH 14855
+    kwds.setdefault('edgecolors', 'none')
 
     boundaries_list = []
     for a in df.columns:
@@ -2864,8 +2863,7 @@ def scatter_plot(data, x, y, by=None, ax=None, figsize=None, grid=False,
     """
     import matplotlib.pyplot as plt
 
-    # workaround because `c='b'` is hardcoded in matplotlibs scatter method
-    kwargs.setdefault('c', plt.rcParams['patch.facecolor'])
+    kwargs.setdefault('edgecolors', 'none')
 
     def plot_group(group, ax):
         xvals = group[x].values