.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        Click :ref:`here <sphx_glr_download_gallery_lines_bars_and_markers_horizontal_barchart_distribution.py>`     to download the full example code
    .. rst-class:: sphx-glr-example-title

    .. _sphx_glr_gallery_lines_bars_and_markers_horizontal_barchart_distribution.py:


=============================================
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``.


.. code-block:: default


    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)
    plt.show()




.. image:: /gallery/lines_bars_and_markers/images/sphx_glr_horizontal_barchart_distribution_001.png
    :alt: horizontal barchart distribution
    :class: sphx-glr-single-img





------------

References
""""""""""

The use of the following functions, methods, classes and modules is shown
in this example:


.. code-block:: default


    import matplotlib
    matplotlib.axes.Axes.barh
    matplotlib.pyplot.barh
    matplotlib.axes.Axes.text
    matplotlib.pyplot.text
    matplotlib.axes.Axes.legend
    matplotlib.pyplot.legend




.. rst-class:: sphx-glr-script-out

 Out:

 .. code-block:: none


    <function legend at 0x7f61601a3b80>




.. _sphx_glr_download_gallery_lines_bars_and_markers_horizontal_barchart_distribution.py:


.. only :: html

 .. container:: sphx-glr-footer
    :class: sphx-glr-footer-example



  .. container:: sphx-glr-download sphx-glr-download-python

     :download:`Download Python source code: horizontal_barchart_distribution.py <horizontal_barchart_distribution.py>`



  .. container:: sphx-glr-download sphx-glr-download-jupyter

     :download:`Download Jupyter notebook: horizontal_barchart_distribution.ipynb <horizontal_barchart_distribution.ipynb>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    Keywords: matplotlib code example, codex, python plot, pyplot
    `Gallery generated by Sphinx-Gallery
    <https://sphinx-gallery.readthedocs.io>`_