

.. _sphx_glr_gallery_api_sankey_basics.py:


================
The Sankey class
================

Demonstrate the Sankey class by producing three basic diagrams.




.. rst-class:: sphx-glr-horizontal


    *

      .. image:: /gallery/api/images/sphx_glr_sankey_basics_001.png
            :scale: 47

    *

      .. image:: /gallery/api/images/sphx_glr_sankey_basics_002.png
            :scale: 47

    *

      .. image:: /gallery/api/images/sphx_glr_sankey_basics_003.png
            :scale: 47





.. code-block:: python

    import numpy as np
    import matplotlib.pyplot as plt

    from matplotlib.sankey import Sankey


    # Example 1 -- Mostly defaults
    # This demonstrates how to create a simple diagram by implicitly calling the
    # Sankey.add() method and by appending finish() to the call to the class.
    Sankey(flows=[0.25, 0.15, 0.60, -0.20, -0.15, -0.05, -0.50, -0.10],
           labels=['', '', '', 'First', 'Second', 'Third', 'Fourth', 'Fifth'],
           orientations=[-1, 1, 0, 1, 1, 1, 0, -1]).finish()
    plt.title("The default settings produce a diagram like this.")
    # Notice:
    #   1. Axes weren't provided when Sankey() was instantiated, so they were
    #      created automatically.
    #   2. The scale argument wasn't necessary since the data was already
    #      normalized.
    #   3. By default, the lengths of the paths are justified.

    # Example 2
    # This demonstrates:
    #   1. Setting one path longer than the others
    #   2. Placing a label in the middle of the diagram
    #   3. Using the scale argument to normalize the flows
    #   4. Implicitly passing keyword arguments to PathPatch()
    #   5. Changing the angle of the arrow heads
    #   6. Changing the offset between the tips of the paths and their labels
    #   7. Formatting the numbers in the path labels and the associated unit
    #   8. Changing the appearance of the patch and the labels after the figure is
    #      created
    fig = plt.figure()
    ax = fig.add_subplot(1, 1, 1, xticks=[], yticks=[],
                         title="Flow Diagram of a Widget")
    sankey = Sankey(ax=ax, scale=0.01, offset=0.2, head_angle=180,
                    format='%.0f', unit='%')
    sankey.add(flows=[25, 0, 60, -10, -20, -5, -15, -10, -40],
               labels=['', '', '', 'First', 'Second', 'Third', 'Fourth',
                       'Fifth', 'Hurray!'],
               orientations=[-1, 1, 0, 1, 1, 1, -1, -1, 0],
               pathlengths=[0.25, 0.25, 0.25, 0.25, 0.25, 0.6, 0.25, 0.25,
                            0.25],
               patchlabel="Widget\nA")  # Arguments to matplotlib.patches.PathPatch()
    diagrams = sankey.finish()
    diagrams[0].texts[-1].set_color('r')
    diagrams[0].text.set_fontweight('bold')
    # Notice:
    #   1. Since the sum of the flows is nonzero, the width of the trunk isn't
    #      uniform.  If verbose.level is helpful (in matplotlibrc), a message is
    #      given in the terminal window.
    #   2. The second flow doesn't appear because its value is zero.  Again, if
    #      verbose.level is helpful, a message is given in the terminal window.

    # Example 3
    # This demonstrates:
    #   1. Connecting two systems
    #   2. Turning off the labels of the quantities
    #   3. Adding a legend
    fig = plt.figure()
    ax = fig.add_subplot(1, 1, 1, xticks=[], yticks=[], title="Two Systems")
    flows = [0.25, 0.15, 0.60, -0.10, -0.05, -0.25, -0.15, -0.10, -0.35]
    sankey = Sankey(ax=ax, unit=None)
    sankey.add(flows=flows, label='one',
               orientations=[-1, 1, 0, 1, 1, 1, -1, -1, 0])
    sankey.add(flows=[-0.25, 0.15, 0.1], label='two',
               orientations=[-1, -1, -1], prior=0, connect=(0, 0))
    diagrams = sankey.finish()
    diagrams[-1].patch.set_hatch('/')
    plt.legend(loc='best')
    # Notice that only one connection is specified, but the systems form a
    # circuit since: (1) the lengths of the paths are justified and (2) the
    # orientation and ordering of the flows is mirrored.

    plt.show()

**Total running time of the script:** ( 0 minutes  0.113 seconds)



.. container:: sphx-glr-footer


  .. container:: sphx-glr-download

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



  .. container:: sphx-glr-download

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

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

    `Generated by Sphinx-Gallery <https://sphinx-gallery.readthedocs.io>`_
