Merge pull request matplotlib#4266 from umairidris/bar_labels

ENH : pass list of strings to label bar/barh plots

Add functionality to plot bar and barh to label bars with list strings (closes matplotlib#2516)

Author: tacaswell

doc/users/whats_new/plotting.rst

@@ -1,3 +1,11 @@
+Plot bar and barh with labels
+`````````````````````````````
+
+Added kwarg "tick_label" to bar and barh to support plotting bar graphs with a
+text label for each bar.
+Example:
+	bar([1, 2], [1, 1], tick_label=['bar1', 'bar2'])
+
 Added center and frame kwargs to pie
 ````````````````````````````````````
 

lib/matplotlib/axes/_axes.py

@@ -1838,6 +1838,10 @@ def bar(self, left, height, width=0.8, bottom=None, **kwargs):
             linewidth; If 0, don't draw edges.
             default: None
 
+        tick_label : string or array-like, optional
+            the tick labels of the bars
+            default: None
+
         xerr : scalar or array-like, optional
             if not None, will be used to generate errorbar(s) on the bar chart
             default: None
@@ -1908,6 +1912,9 @@ def bar(self, left, height, width=0.8, bottom=None, **kwargs):
         edgecolor = kwargs.pop('edgecolor', None)
         linewidth = kwargs.pop('linewidth', None)
 
+        tick_label = kwargs.pop('tick_label', None)
+        label_ticks_flag = tick_label is not None
+
         # Because xerr and yerr will be passed to errorbar,
         # most dimension checking and processing will be left
         # to the errorbar method.
@@ -1938,6 +1945,7 @@ def make_iterable(x):
         _bottom = bottom
         bottom = make_iterable(bottom)
         linewidth = make_iterable(linewidth)
+        tick_label = make_iterable(tick_label)
 
         adjust_ylim = False
         adjust_xlim = False
@@ -1956,6 +1964,9 @@ def make_iterable(x):
                 width *= nbars
             if len(bottom) == 1:
                 bottom *= nbars
+
+            tick_label_axis = self.xaxis
+            tick_label_position = left
         elif orientation == 'horizontal':
             self._process_unit_info(xdata=width, ydata=bottom, kwargs=kwargs)
             if log:
@@ -1971,11 +1982,16 @@ def make_iterable(x):
                 left *= nbars
             if len(height) == 1:
                 height *= nbars
+
+            tick_label_axis = self.yaxis
+            tick_label_position = bottom
         else:
             raise ValueError('invalid orientation: %s' % orientation)
 
         if len(linewidth) < nbars:
             linewidth *= nbars
+        if len(tick_label) < nbars:
+            tick_label *= nbars
 
         if color is None:
             color = [None] * nbars
@@ -2008,6 +2024,9 @@ def make_iterable(x):
         if len(bottom) != nbars:
             raise ValueError("incompatible sizes: argument 'bottom' "
                              "must be length %d or scalar" % nbars)
+        if len(tick_label) != nbars:
+            raise ValueError("incompatible sizes: argument 'tick_label' "
+                             "must be length %d or string" % nbars)
 
         patches = []
 
@@ -2103,6 +2122,10 @@ def make_iterable(x):
         bar_container = BarContainer(patches, errorbar, label=label)
         self.add_container(bar_container)
 
+        if label_ticks_flag:
+            tick_label_axis.set_ticks(tick_label_position)
+            tick_label_axis.set_ticklabels(tick_label)
+
         return bar_container
 
     @docstring.dedent_interpd
@@ -2148,6 +2171,9 @@ def barh(self, bottom, width, height=0.8, left=None, **kwargs):
             width of bar edge(s). If None, use default
             linewidth; If 0, don't draw edges.
 
+        tick_label : string or array-like, optional, default: None
+            the tick labels of the bars
+
         xerr : scalar or array-like, optional, default: None
             if not None, will be used to generate errorbar(s) on the bar chart
 

lib/matplotlib/tests/baseline_images/test_axes/bar_tick_label_multiple.png

@@ -131,7 +131,6 @@ def test_twinx_cla():
 
 @image_comparison(baseline_images=["minorticks_on_rcParams_both"], extensions=['png'])
 def test_minorticks_on_rcParams_both():
-
     fig = plt.figure()
     matplotlib.rcParams['xtick.minor.visible'] = True
     matplotlib.rcParams['ytick.minor.visible'] = True
@@ -1011,6 +1010,32 @@ def test_marker_edges():
     ax.plot(x+0.2, np.sin(x), 'y.', ms=30.0, mew=2, mec='b')
 
 
+@image_comparison(baseline_images=['bar_tick_label_single'],
+                  extensions=['png'])
+def test_bar_tick_label_single():
+    # From 2516: plot bar with array of string labels for x axis
+    ax = plt.gca()
+    ax.bar(0, 1 , tick_label='a')
+
+
+@image_comparison(baseline_images=['bar_tick_label_multiple'],
+                  extensions=['png'])
+def test_bar_tick_label_multiple():
+    # From 2516: plot bar with array of string labels for x axis
+    ax = plt.gca()
+    ax.bar([1, 2.5], [1, 2], width=[0.2, 0.5], tick_label=['a', 'b'],
+           align='center')
+
+
+@image_comparison(baseline_images=['barh_tick_label'],
+                  extensions=['png'])
+def test_barh_tick_label():
+    # From 2516: plot barh with array of string labels for y axis
+    ax = plt.gca()
+    ax.barh([1, 2.5], [1, 2], height=[0.2, 0.5], tick_label=['a', 'b'],
+            align='center')
+
+
 @image_comparison(baseline_images=['hist_log'],
                   remove_text=True)
 def test_hist_log():