BUG: Fix regression for RGB(A) color arguments (#16701)

* Add test

* Pass tuples that are RGB or RGBA like in list

* Update what's new

* change whatsnew to reflect regression fix

* Add test for RGBA as well

(cherry picked from commit 125c414)

doc/source/whatsnew/v0.20.3.txt

@@ -59,7 +59,7 @@ I/O
 
 Plotting
 ^^^^^^^^
-
+- Fix regression in series plotting that prevented RGB and RGBA tuples from being used as color arguments (:issue:`16233`)
 
 
 

pandas/plotting/_core.py

@@ -186,6 +186,11 @@ def _validate_color_args(self):
             # support series.plot(color='green')
             self.kwds['color'] = [self.kwds['color']]
 
+        if ('color' in self.kwds and isinstance(self.kwds['color'], tuple) and
+                self.nseries == 1 and len(self.kwds['color']) in (3, 4)):
+            # support RGB and RGBA tuples in series plot
+            self.kwds['color'] = [self.kwds['color']]
+
         if ('color' in self.kwds or 'colors' in self.kwds) and \
                 self.colormap is not None:
             warnings.warn("'color' and 'colormap' cannot be used "

pandas/tests/plotting/test_frame.py

@@ -158,6 +158,12 @@ def test_color_single_series_list(self):
         df = DataFrame({"A": [1, 2, 3]})
         _check_plot_works(df.plot, color=['red'])
 
+    def test_rgb_tuple_color(self):
+        # GH 16695
+        df = DataFrame({'x': [1, 2], 'y': [3, 4]})
+        _check_plot_works(df.plot, x='x', y='y', color=(1, 0, 0))
+        _check_plot_works(df.plot, x='x', y='y', color=(1, 0, 0, 0.5))
+
     def test_color_empty_string(self):
         df = DataFrame(randn(10, 2))
         with pytest.raises(ValueError):