VIS/DOC: clean-up plots in the docs

[jorisvandenbossche]

This is of course taste, but I personally find some of the plots on the docs not very pleasing to the eyes.
Some different things:

• Too dense minor gridlines (solved by using mpl 1.4):
  • Eg the first plot on the page: http://pandas-docs.github.io/pandas-docs-travis/visualization.html#basic-plotting-plot
  • It becomes worse when the plots become smaller: http://pandas-docs.github.io/pandas-docs-travis/visualization.html#using-layout-and-targetting-multiple-axes
  • This could be solved using the new matplotlib styles or adapting our own options.display.mpl_default style
• Overlapping axis labels (see also comment from here: VIS: default LinePlot rotation of 0 #8301 (comment)) (DOC: Use square figsize for pie plots #8391):
  • See the examples with multiple axes: http://pandas-docs.github.io/pandas-docs-travis/visualization.html#using-layout-and-targetting-multiple-axes -> a lot of overlapping axis labels
• Use square pie plots (DOC: Use square figsize for pie plots #8391)
• ...

[TomAugspurger]

Agreed. What version of matplotlib are the docs built with? 1.4 added the style method. We could just use the ggplot style

[jorisvandenbossche]

On travis, the docs are built in the third job, which now uses matplotlib 1.3.1, but I think we should certainly update the matplotlib version of one of the jobs to 1.4, so we can take that one.
For releases, I did the building for the last two releases, so I can just use matplotlib 1.4 when building the docs, that is no problem.

So +1 on using matplotlib.style instead of our own solution with options.display.mpl_style

[jorisvandenbossche]

@TomAugspurger Strange thing is, if I run the plots locally, eg the first plot http://pandas.pydata.org/pandas-docs/stable/visualization.html#basic-plotting-plot, then I don't get these dense gridlines, but only the major ones. I don't see why it is different in the docs.

UPDATE: seems different between matplotlib version 1.3.1 and 1.4.0. So updating the doc builds to 1.4 would maybe be enough to have less dense gridlines.

[jreback]

@jorisvandenbossche @TomAugspurger ? (going to leave on 0.15.0, but since docs can fiddle even after RC)

[jorisvandenbossche]

@TomAugspurger are we also going to use matplotlib.style ? (ggplot eg)

[TomAugspurger]

👍 for ggplot.

[jorisvandenbossche]

Do you want to do a PR? (I can also do, but then it will be for later after rc)