[matplotlib-devel] handling labeled data

[Thomas C. <tca...@gm...>]

Hey all,

Everyone should be aware of
https://github.com/matplotlib/matplotlib/pull/4787 which is both a very
simple, but very important change to the mpl API by providing a minimal API
to pass labeled data (that is anything that `foo[key]` return an array-like
object) into mpl plotting functions.

This is due to Fernando and Brian's persuasive case to the importance of
starting to address labeled data in mpl and it is now or in 6-9 months

The general approach follows R / seaborn / panadas and allows users to pass
in a `data` kwarg which if present, any data fields which are strings are
replaced by a call to `data[key]`.  In code

   ax.plot(labeled_data['a'], labeled_data['b'])

and

  ax.plot('a', 'b', data=labeled_data)

are equivalent.

This is the minimal change to get quality of life for users who work with
labeled data at the repl and to put a flag in the sand for the API that
down stream projects should be targeting.

Major changes to what the plotting functions do (inferring labels,
inferring what computation to do etc) are out of scope for _this_ PR which
I want to see included in 1.5.  What a higher-level API which can make use
of the additional meta-data available looks like is a much larger
discussion which will must have input from all of the stake holders (ex
IPython, pandas, bokeh, seaborn, xray).

Tom