ENH/BUG: color cannot be applied to line subplots

Author: sinhrks

doc/source/whatsnew/v0.16.1.txt

@@ -207,6 +207,10 @@ API changes
 
 - By default, ``read_csv`` and ``read_table`` will now try to infer the compression type based on the file extension. Set ``compression=None`` to restore the previous behavior (no decompression). (:issue:`9770`)
 
+
+- Line and kde plot with ``subplots=True`` now uses default colors, not all black. Specify ``color='k'`` to draw all lines in black (:issue:`9894`)
+
+
 .. _whatsnew_0161.performance:
 
 Performance Improvements
@@ -256,6 +260,11 @@ Bug Fixes
 - Bug in which ``SparseDataFrame`` could not take `nan` as a column name (:issue:`8822`)
 - Bug in ``to_msgpack`` and ``read_msgpack`` zlib and blosc compression support (:issue:`9783`)
 
+
+
+- Bug in line and kde plot cannot accept multiple colors when ``subplots=True`` (:issue:`9894`)
+
+
 - Bug ``GroupBy.size`` doesn't attach index name properly if grouped by ``TimeGrouper`` (:issue:`9925`)
 - Bug causing an exception in slice assignments because ``length_of_indexer`` returns wrong results (:issue:`9995`)
 - Bug in csv parser causing lines with initial whitespace plus one non-space character to be skipped. (:issue:`9710`)

pandas/tests/test_graphics.py

@@ -2836,6 +2836,55 @@ def test_line_colors(self):
         ax = df.ix[:, [0]].plot(color='DodgerBlue')
         self._check_colors(ax.lines, linecolors=['DodgerBlue'])
 
+    @slow
+    def test_line_colors_and_styles_subplots(self):
+        from matplotlib import cm
+        default_colors = self.plt.rcParams.get('axes.color_cycle')
+
+        df = DataFrame(randn(5, 5))
+
+        axes = df.plot(subplots=True)
+        for ax, c in zip(axes, list(default_colors)):
+            self._check_colors(ax.get_lines(), linecolors=c)
+        tm.close()
+
+        # single color
+        axes = df.plot(subplots=True, color='k')
+        for ax in axes:
+            self._check_colors(ax.get_lines(), linecolors=['k'])
+        tm.close()
+
+        custom_colors = 'rgcby'
+        axes = df.plot(color=custom_colors, subplots=True)
+        for ax, c in zip(axes, list(custom_colors)):
+            self._check_colors(ax.get_lines(), linecolors=[c])
+        tm.close()
+
+        rgba_colors = lmap(cm.jet, np.linspace(0, 1, len(df)))
+        for cmap in ['jet', cm.jet]:
+            axes = df.plot(colormap=cmap, subplots=True)
+            for ax, c in zip(axes, rgba_colors):
+                self._check_colors(ax.get_lines(), linecolors=[c])
+            tm.close()
+
+        # make color a list if plotting one column frame
+        # handles cases like df.plot(color='DodgerBlue')
+        axes = df.ix[:, [0]].plot(color='DodgerBlue', subplots=True)
+        self._check_colors(axes[0].lines, linecolors=['DodgerBlue'])
+
+        # single character style
+        axes = df.plot(style='r', subplots=True)
+        for ax in axes:
+            self._check_colors(ax.get_lines(), linecolors=['r'])
+        tm.close()
+
+        # list of styles
+        styles = list('rgcby')
+        axes = df.plot(style=styles, subplots=True)
+        for ax, c in zip(axes, styles):
+            self._check_colors(ax.get_lines(), linecolors=[c])
+        tm.close()
+
     @slow
     def test_area_colors(self):
         from matplotlib import cm
@@ -2934,6 +2983,58 @@ def test_kde_colors(self):
         rgba_colors = lmap(cm.jet, np.linspace(0, 1, len(df)))
         self._check_colors(ax.get_lines(), linecolors=rgba_colors)
 
+    @slow
+    def test_kde_colors_and_styles_subplots(self):
+        tm._skip_if_no_scipy()
+        _skip_if_no_scipy_gaussian_kde()
+
+        from matplotlib import cm
+        default_colors = self.plt.rcParams.get('axes.color_cycle')
+
+        df = DataFrame(randn(5, 5))
+
+        axes = df.plot(kind='kde', subplots=True)
+        for ax, c in zip(axes, list(default_colors)):
+            self._check_colors(ax.get_lines(), linecolors=[c])
+        tm.close()
+
+        # single color
+        axes = df.plot(kind='kde', color='k', subplots=True)
+        for ax in axes:
+            self._check_colors(ax.get_lines(), linecolors=['k'])
+        tm.close()
+
+        custom_colors = 'rgcby'
+        axes = df.plot(kind='kde', color=custom_colors, subplots=True)
+        for ax, c in zip(axes, list(custom_colors)):
+            self._check_colors(ax.get_lines(), linecolors=[c])
+        tm.close()
+
+        rgba_colors = lmap(cm.jet, np.linspace(0, 1, len(df)))
+        for cmap in ['jet', cm.jet]:
+            axes = df.plot(kind='kde', colormap=cmap, subplots=True)
+            for ax, c in zip(axes, rgba_colors):
+                self._check_colors(ax.get_lines(), linecolors=[c])
+            tm.close()
+
+        # make color a list if plotting one column frame
+        # handles cases like df.plot(color='DodgerBlue')
+        axes = df.ix[:, [0]].plot(kind='kde', color='DodgerBlue', subplots=True)
+        self._check_colors(axes[0].lines, linecolors=['DodgerBlue'])
+
+        # single character style
+        axes = df.plot(kind='kde', style='r', subplots=True)
+        for ax in axes:
+            self._check_colors(ax.get_lines(), linecolors=['r'])
+        tm.close()
+
+        # list of styles
+        styles = list('rgcby')
+        axes = df.plot(kind='kde', style=styles, subplots=True)
+        for ax, c in zip(axes, styles):
+            self._check_colors(ax.get_lines(), linecolors=[c])
+        tm.close()
+
     @slow
     def test_boxplot_colors(self):
 

pandas/tools/plotting.py

@@ -1262,36 +1262,36 @@ def on_right(self, i):
         if isinstance(self.secondary_y, (tuple, list, np.ndarray, Index)):
             return self.data.columns[i] in self.secondary_y
 
-    def _get_style(self, i, col_name):
-        style = ''
-        if self.subplots:
-            style = 'k'
+    def _get_colors(self, num_colors=None, color_kwds='color'):
+        if num_colors is None:
+            num_colors = self.nseries
 
+        return _get_standard_colors(num_colors=num_colors,
+                                    colormap=self.colormap,
+                                    color=self.kwds.get(color_kwds))
+
+    def _apply_style_colors(self, colors, kwds, col_num, label):
+        """
+        Manage style and color based on column number and its label.
+        Returns tuple of appropriate style and kwds which "color" may be added.
+        """
+        style = None
         if self.style is not None:
             if isinstance(self.style, list):
                 try:
-                    style = self.style[i]
+                    style = self.style[col_num]
                 except IndexError:
                     pass
             elif isinstance(self.style, dict):
-                style = self.style.get(col_name, style)
+                style = self.style.get(label, style)
             else:
                 style = self.style
 
-        return style or None
-
-    def _get_colors(self, num_colors=None, color_kwds='color'):
-        if num_colors is None:
-            num_colors = self.nseries
-
-        return _get_standard_colors(num_colors=num_colors,
-                                    colormap=self.colormap,
-                                    color=self.kwds.get(color_kwds))
-
-    def _maybe_add_color(self, colors, kwds, style, i):
         has_color = 'color' in kwds or self.colormap is not None
-        if has_color and (style is None or re.match('[a-z]+', style) is None):
-            kwds['color'] = colors[i % len(colors)]
+        nocolor_style = style is None or re.match('[a-z]+', style) is None
+        if (has_color or self.subplots) and nocolor_style:
+            kwds['color'] = colors[col_num % len(colors)]
+        return style, kwds
 
     def _parse_errorbars(self, label, err):
         '''
@@ -1612,9 +1612,8 @@ def _make_plot(self):
         colors = self._get_colors()
         for i, (label, y) in enumerate(it):
             ax = self._get_ax(i)
-            style = self._get_style(i, label)
             kwds = self.kwds.copy()
-            self._maybe_add_color(colors, kwds, style, i)
+            style, kwds = self._apply_style_colors(colors, kwds, i, label)
 
             errors = self._get_errorbars(label=label, index=i)
             kwds = dict(kwds, **errors)
@@ -1963,13 +1962,13 @@ def _make_plot(self):
         colors = self._get_colors()
         for i, (label, y) in enumerate(self._iter_data()):
             ax = self._get_ax(i)
-            style = self._get_style(i, label)
-            label = com.pprint_thing(label)
 
             kwds = self.kwds.copy()
+
+            label = com.pprint_thing(label)
             kwds['label'] = label
-            self._maybe_add_color(colors, kwds, style, i)
 
+            style, kwds = self._apply_style_colors(colors, kwds, i, label)
             if style is not None:
                 kwds['style'] = style