Spaced hierarchical index

[Maggie-M]

Originally posted by afonit. For original issue and full discussion, click here.

from a discussion on the mailing list:
https://groups.google.com/a/continuum.io/forum/#!topic/bokeh/Lq5LX6yH-fU

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Currently bokeh can have hierarchical indexes on plots, but they are slotted for each tick, see in this example:

import pandas as pd
import datetime
from bokeh.charts import Bar, output_notebook, show

output_notebook()

data = {
    'month': ['2016-01-01','2016-02-01', '2016-01-01'],
    'work_location': ['site_a', 'site_a', 'site_b'],
    'nps': [50.0, 33.3, -25.0]
}

df = pd.DataFrame(data)

p = Bar(df, values='nps', label=['work_location', 'month'])
show(p)

Produces the following plot:

On the left is the current, on the right the axis is parsed visually so it is easier/quicker to interpret and see the groups.

Here is an additional example:
http://news.infragistics.com/cfs-filesystemfile.ashx/__key/CommunityServer.Discussions.Components.Files/265/4718.Capture.PNG

Again, just floating the idea as I think it lends visual power to the graph in making the content of the axis (when it is hierarchical like this) easier to parse than the current look.