The Sankey class#

Demonstrate the Sankey class by producing three basic diagrams.

importmatplotlib.pyplotaspltfrommatplotlib.sankeyimportSankey

Example 1 -- Mostly defaults

This demonstrates how to create a simple diagram by implicitly calling theSankey.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 werecreated automatically.

2. The scale argument wasn't necessary since the data was alreadynormalized.

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 iscreated

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.PathPatchdiagrams=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'tuniform. The matplotlib logging system logs this at the DEBUG level.

2. The second flow doesn't appear because its value is zero. Again, this islogged at the DEBUG level.

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()

Notice that only one connection is specified, but the systems form acircuit since: (1) the lengths of the paths are justified and (2) theorientation and ordering of the flows is mirrored.

plt.show()

Total running time of the script: (0 minutes 1.127 seconds)

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