>>> """
======================================
Long chain of connections using Sankey
======================================

Demonstrate/test the Sankey class by producing a long chain of connections.
"""
... 
... import matplotlib.pyplot as plt
... from matplotlib.sankey import Sankey
... 
... links_per_side = 6
... 
... 
... def side(sankey, n=1):
...     """Generate a side chain."""
...     prior = len(sankey.diagrams)
...     for i in range(0, 2*n, 2):
...         sankey.add(flows=[1, -1], orientations=[-1, -1],
...                    patchlabel=str(prior + i),
...                    prior=prior + i - 1, connect=(1, 0), alpha=0.5)
...         sankey.add(flows=[1, -1], orientations=[1, 1],
...                    patchlabel=str(prior + i + 1),
...                    prior=prior + i, connect=(1, 0), alpha=0.5)
... 
... 
... def corner(sankey):
...     """Generate a corner link."""
...     prior = len(sankey.diagrams)
...     sankey.add(flows=[1, -1], orientations=[0, 1],
...                patchlabel=str(prior), facecolor='k',
...                prior=prior - 1, connect=(1, 0), alpha=0.5)
... 
... 
... fig = plt.figure()
... ax = fig.add_subplot(1, 1, 1, xticks=[], yticks=[],
...                      title="Why would you want to do this?\n(But you could.)")
... sankey = Sankey(ax=ax, unit=None)
... sankey.add(flows=[1, -1], orientations=[0, 1],
...            patchlabel="0", facecolor='k',
...            rotation=45)
... side(sankey, n=links_per_side)
... corner(sankey)
... side(sankey, n=links_per_side)
... corner(sankey)
... side(sankey, n=links_per_side)
... corner(sankey)
... side(sankey, n=links_per_side)
... sankey.finish()
... # Notice:
... # 1. The alignment doesn't drift significantly (if at all; with 16007
... #    subdiagrams there is still closure).
... # 2. The first diagram is rotated 45 deg, so all other diagrams are rotated
... #    accordingly.
... 
... plt.show()
... 
... 
... #############################################################################
... #
... # .. admonition:: References
... #
... #    The use of the following functions, methods, classes and modules is shown
... #    in this example:
... #
... #    - `matplotlib.sankey`
... #    - `matplotlib.sankey.Sankey`
... #    - `matplotlib.sankey.Sankey.add`
... #    - `matplotlib.sankey.Sankey.finish`
...