Drawing barplots

The incenp.plotting.bar module provides a barplot function intended to facilitate the creation of bar plots from multi-indexed data.

The module uses the same notion of tracks and subtracks as the incenp.plotting.scatter module.

Sample data

Let’s create a multi-indexed DataFrame which we will use in the examples below:

index = pd.MultiIndex.from_arrays([
        ['foo'] * 2 + ['bar'] * 2 + ['baz'] * 2 + ['qux'] * 2,
        ['one', 'two'] * 4
    ],
    names=['first', 'second']
    )
df = pd.DataFrame(np.random.randint(0, 100, size=(8,2)),
                  index = index, columns=['A', 'B'])

This creates a DataFrame with 2 columns (A and B) and 8 rows, indexed in two levels (level first, with 4 distinct values foo, bar, baz, and qux; and level second, with 2 distinct values one and two).

Quick start

Here is a quick example illustrating the main points of the barplot function (ax is supposed to be a matplotlib.axes.Axes object):

barplot(ax, df, column='A',
        tracks=['foo', 'bar', 'bax'],
        subtracks=['one', 'two'], subtrackname='second',
        ncolumn='B')
ax.legend(['one', 'two'], loc='upper center')

A sample bar plot.

The column parameter indicates which column in the DataFrame contains the value to plot. The tracks and subtracks parameters are used to select and distribute the rows along the tracks and subtracks, in a similar way to the scatterplot function of the incenp.plotting.scatter module.

The ncolumn parameter, if included, indicates which column in the DataFrame contains the number of samples, to be displayed on top of every bar.