title: Connecting flows in matplotlib sankey diagram
body: <p>I am using matplotlibs <strong><code>sankey</code></strong> functionality and have a problem with connecting two flows. Basically, I just want to connect the flow <strong><code>Qab,rekup</code></strong> to the end of the flow <strong><code>Qzu,rekup</code></strong> (see Screenshot).</p>
  
  <p>Seems to be quite easy but I still haven't figured out how to manage this.</p>
  
  <p>Here's the screenshot: <a href="https://www.dropbox.com/s/2satz9ryniy958v/Sankey.png?dl=0" rel="nofollow noreferrer">https://www.dropbox.com/s/2satz9ryniy958v/Sankey.png?dl=0</a>
  <img src="https://i.stack.imgur.com/fdyoD.png" alt="enter image description here">
  Here's the code:</p>
  
  <pre><code>import numpy as np
  import matplotlib.pyplot as plt
  from matplotlib.sankey import Sankey
  
  fig = plt.figure()
  ax = fig.add_subplot(1, 1, 1, xticks=[], yticks=[],
                       title="Vereinfachtes Kraftwerksmodell")
  sankey = Sankey(ax=ax, unit=None)
  sankey.add(flows=[1.0, -0.3, -0.1, -0.1, -0.5],
             labels=['P$el$', 'Q$ab,vd$', 'P$vl,vd$', 'P$vl,mot$', ''],
             label='Laden',
             orientations=[0, -1, 1, 1, 0])
  sankey.add(flows=[0.5, 0.1, 0.1, -0.1, -0.1, -0.1, -0.1, -0.3], fc='#37c959',
             label='Entladen',
             labels=['P$mech$', 'Q$zu,ex$', 'Q$zu,rekup$', 'P$vl,tb$', 'P$vl,gen$',         'Q$ab,tb$', 'Q$ab,rekup$', 'P$nutz$'],
             orientations=[0, -1, -1, 1, 1, -1, -1, 0], prior=0, connect=(4, 0))
  sankey.add(flows=[-0.1, 0.1],
             label='Rekuperator',
             #labels=['bla'],
             orientations=[1,1], prior=1, connect=(2, 0))
  diagrams = sankey.finish()
  diagrams[-1].patch.set_hatch('/')
  plt.legend(loc='lower right')
  plt.show()
  </code></pre>
  
  <p><strong>Does anyone have an idea?</strong></p>
  
  <p>Thanks in advance
  Cord</p>