matplotlib · timhoffm · May 26, 2019 · May 26, 2019
diff --git a/.flake8 b/.flake8
@@ -140,6 +140,7 @@ per-file-ignores =
     examples/lines_bars_and_markers/fill.py: E402
     examples/lines_bars_and_markers/fill_between_demo.py: E402
     examples/lines_bars_and_markers/filled_step.py: E402
+    examples/lines_bars_and_markers/horizontal_barchart_distribution.py: E402
     examples/lines_bars_and_markers/joinstyle.py: E402
     examples/lines_bars_and_markers/scatter_piecharts.py: E402
     examples/lines_bars_and_markers/scatter_with_legend.py: E402

diff --git a/examples/lines_bars_and_markers/horizontal_barchart_distribution.py b/examples/lines_bars_and_markers/horizontal_barchart_distribution.py
@@ -0,0 +1,90 @@
+"""
+=============================================
+Discrete distribution as horizontal bar chart
+=============================================
+
+Stacked bar charts can be used to visualize discrete distributions.
+
+This example visualizes the result of a survey in which people could rate
+their agreement to questions on a five-element scale.
+
+The horizontal stacking is achieved by calling `~.Axes.barh()` for each
+category and passing the starting point as the cumulative sum of the
+already drawn bars via the parameter ``left``.
+"""
+
+import numpy as np
+import matplotlib.pyplot as plt
+
+
+category_names = ['Strongly disagree', 'Disagree',
+                  'Neither agree nor disagree', 'Agree', 'Strongly agree']
+results = {
+    'Question 1': [10, 15, 17, 32, 26],
+    'Question 2': [26, 22, 29, 10, 13],
+    'Question 3': [35, 37, 7, 2, 19],
+    'Question 4': [32, 11, 9, 15, 33],
+    'Question 5': [21, 29, 5, 5, 40],
+    'Question 6': [8, 19, 5, 30, 38]
+}
+
+
+def survey(results, category_names):
+    """
+    Parameters
+    ----------
+    results : dict
+        A mapping from question labels to a list of answers per category.
+        It is assumed all lists contain the same number of entries and that
+        it matches the length of *category_names*.
+    category_names : list of str
+        The category labels.
+    """
+    labels = list(results.keys())
+    data = np.array(list(results.values()))
+    data_cum = data.cumsum(axis=1)
+    category_colors = plt.get_cmap('RdYlGn')(
+        np.linspace(0.15, 0.85, data.shape[1]))
+
+    fig, ax = plt.subplots(figsize=(9.2, 5))
+    ax.invert_yaxis()
+    ax.xaxis.set_visible(False)
+    ax.set_xlim(0, np.sum(data, axis=1).max())
+
+    for i, (colname, color) in enumerate(zip(category_names, category_colors)):
+        widths = data[:, i]
+        starts = data_cum[:, i] - widths
+        ax.barh(labels, widths, left=starts, height=0.5,
+                label=colname, color=color)
+        xcenters = starts + widths / 2
+
+        r, g, b, _ = color
+        text_color = 'white' if r * g * b < 0.5 else 'darkgrey'
+        for y, (x, c) in enumerate(zip(xcenters, widths)):
+            ax.text(x, y, str(int(c)), ha='center', va='center',
+                    color=text_color)
+    ax.legend(ncol=len(category_names), bbox_to_anchor=(0, 1),
+              loc='lower left', fontsize='small')
+
+    return fig, ax
+
+
+survey(results, category_names)
+
+#############################################################################
+#
+# ------------
+#
+# References
+# """"""""""
+#
+# The use of the following functions, methods, classes and modules is shown
+# in this example:
+
+import matplotlib
+matplotlib.axes.Axes.barh
+matplotlib.pyplot.barh
+matplotlib.axes.Axes.text
+matplotlib.pyplot.text
+matplotlib.axes.Axes.legend
+matplotlib.pyplot.legend