.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/statistics/multiple_histograms_side_by_side.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. meta::
        :keywords: codex

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

        :ref:`Go to the end <sphx_glr_download_gallery_statistics_multiple_histograms_side_by_side.py>`
        to download the full example code

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_gallery_statistics_multiple_histograms_side_by_side.py:


==========================================
Producing multiple histograms side by side
==========================================

This example plots horizontal histograms of different samples along
a categorical x-axis. Additionally, the histograms are plotted to
be symmetrical about their x-position, thus making them very similar
to violin plots.

To make this highly specialized plot, we can't use the standard ``hist``
method. Instead, we use ``barh`` to draw the horizontal bars directly. The
vertical positions and lengths of the bars are computed via the
``np.histogram`` function. The histograms for all the samples are
computed using the same range (min and max values) and number of bins,
so that the bins for each sample are in the same vertical positions.

Selecting different bin counts and sizes can significantly affect the
shape of a histogram. The Astropy docs have a great section on how to
select these parameters:
http://docs.astropy.org/en/stable/visualization/histogram.html

.. GENERATED FROM PYTHON SOURCE LINES 23-64

.. code-block:: Python


    import matplotlib.pyplot as plt
    import numpy as np

    np.random.seed(19680801)
    number_of_bins = 20

    # An example of three data sets to compare
    number_of_data_points = 387
    labels = ["A", "B", "C"]
    data_sets = [np.random.normal(0, 1, number_of_data_points),
                 np.random.normal(6, 1, number_of_data_points),
                 np.random.normal(-3, 1, number_of_data_points)]

    # Computed quantities to aid plotting
    hist_range = (np.min(data_sets), np.max(data_sets))
    binned_data_sets = [
        np.histogram(d, range=hist_range, bins=number_of_bins)[0]
        for d in data_sets
    ]
    binned_maximums = np.max(binned_data_sets, axis=1)
    x_locations = np.arange(0, sum(binned_maximums), np.max(binned_maximums))

    # The bin_edges are the same for all of the histograms
    bin_edges = np.linspace(hist_range[0], hist_range[1], number_of_bins + 1)
    heights = np.diff(bin_edges)
    centers = bin_edges[:-1] + heights / 2

    # Cycle through and plot each histogram
    fig, ax = plt.subplots()
    for x_loc, binned_data in zip(x_locations, binned_data_sets):
        lefts = x_loc - 0.5 * binned_data
        ax.barh(centers, binned_data, height=heights, left=lefts)

    ax.set_xticks(x_locations, labels)

    ax.set_ylabel("Data values")
    ax.set_xlabel("Data sets")

    plt.show()




.. image-sg:: /gallery/statistics/images/sphx_glr_multiple_histograms_side_by_side_001.png
   :alt: multiple histograms side by side
   :srcset: /gallery/statistics/images/sphx_glr_multiple_histograms_side_by_side_001.png, /gallery/statistics/images/sphx_glr_multiple_histograms_side_by_side_001_2_00x.png 2.00x
   :class: sphx-glr-single-img





.. GENERATED FROM PYTHON SOURCE LINES 65-71

.. admonition:: References

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

   - `matplotlib.axes.Axes.barh` / `matplotlib.pyplot.barh`


.. _sphx_glr_download_gallery_statistics_multiple_histograms_side_by_side.py:

.. only:: html

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

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

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

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

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


.. only:: html

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

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_