Holoviews: Sankey diagram

[jbednar]

It would be nice to offer a Sankey diagram. MPL offers one (http://matplotlib.org/api/sankey_api.html), but a Bokeh-based one could work like the d3 sankey, where being interactive makes it much easier to follow.

[slamer59]

d3.js has plenty of example.
I'm using this combined with django:
d3-sankey-diagram

To play with some data

And I have note tested yet but there is
jupyter widget

[MatthewSteen]

:+1:

[philippjfr]

Here is my initial effort at porting d3-Sankey to HoloViews: https://anaconda.org/philippjfr/sankey/notebook

The remaining bits should be easy once the TriMesh and Chord PRs have been merged.

[jbednar]

Cool!!

[philippjfr]

Now with labels:

[slamer59]

Really nice ! Tanks for your effort !

Le ven. 8 déc. 2017 16:57, Philipp Rudiger [e-mail] a
écrit :

Now with labels:

[image: screen shot 2017-12-08 at 3 56 08 pm]
https://user-images.githubusercontent.com/1550771/33773611-63ecd5e8-dc30-11e7-962d-48a510ddafb7.png

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[jlstevens]

At a glance the approach Philipp uses in that notebooks looks reasonable (Sankey being a type of graph) so I would be happy to see a PR and maybe this new element can make it into the next release.

[dizhu1991]

@philippjfr Hi, I was trying to draw a sankey graph of visitor paths' starts and ends in a museum. So the left and right labels will come from the same set of elements (there will be edges like a to b and b to a at the same time). I tried holoview and there was an error "Sankey diagram only supports acyclic graphs". How should I solve this problem?

[denson]

@dizhu1991 Sankey is not for visualizing two way relationships as you describe.

You could try loading it into a networkx MultiDiGraph and then draw the MultiDiGraph.

There is work being done to attempt to create something similar to Sankey that does allow cycles:

http://data-analytics.net/cep/References_files/Enabling%20Loops%20in%20Sankey%20Diagrams.html

http://bl.ocks.org/soxofaan/bb6f91d57dc4b6afe91d

[TizianoGC]

@denson: Actually, plotting Sankey cyclic graphs are quite useful!
There are many examples which show cycles; even Sankey himself used them.

Holoviews developers, could you please add this new feature? It would be a pity having to switch to another library just for that!

Thanks

[jbednar]

HoloViews users, please feel free to implement cyclic support and submit a PR! :-) If you find another library with an appropriate open-source license, maybe you can find the code involved and see if it can guide your implementation. I don't currently know of a need for cyclic Sankey from any of the core developers any time soon, and otherwise this is definitely a case where a user contribution would be able to make it happen!