python - Double donut chart in matplotlib

9
votes

Alright matplotlib afficionados, we know how to plot a donut chart, but what is better than a donut chart? A double-donut chart. Specifically: We have a set of elements that fall into disjoint categories and sub-categories of the first categorization. The donut chart should have slices for the categories in the outer ring and slices for the sub-categories in the inner ring, obviously aligned with the outer slices.

Is there any library that provides this or do we need to work this out here?

enter image description here

2
pythonmatplotlibplotcharts
You could plot two donuts on the same figure, with a smaller outer radius for one of them. - Arya McCarthy
Is this question asking us to recommend or find software library, or is it asking how to do this kind of plot with matplotlib? - ImportanceOfBeingErnest

2 Answers

18
votes

To obtain a double donut chart, you can plot as many pie charts in the same plot as you want. So the outer pie would have a width set to its wedges and the inner pie would have a radius that is less or equal 1-width.

import matplotlib.pyplot as plt
import numpy as np

fig, ax = plt.subplots()
ax.axis('equal')
width = 0.3

cm = plt.get_cmap("tab20c")
cout = cm(np.arange(3)*4)
pie, _ = ax.pie([120,77,39], radius=1, labels=list("ABC"), colors=cout)
plt.setp( pie, width=width, edgecolor='white')

cin = cm(np.array([1,2,5,6,9,10]))
labels = list(map("".join, zip(list("aabbcc"),map(str, [1,2]*3))))
pie2, _ = ax.pie([60,60,37,40,29,10], radius=1-width, labels=labels,
                                      labeldistance=0.7, colors=cin)
plt.setp( pie2, width=width, edgecolor='white')
plt.show()

enter image description here

Note: I made this code also available in the matplotlib gallery as nested pie example.

4
votes

I adapted the example you provided; you can tackle your problem by plotting two donuts on the same figure, with a smaller outer radius for one of them. 

import matplotlib.pyplot as plt
import numpy as np

def make_pie(sizes, text,colors,labels, radius=1):
    col = [[i/255 for i in c] for c in colors]

    plt.axis('equal')
    width = 0.35
    kwargs = dict(colors=col, startangle=180)
    outside, _ = plt.pie(sizes, radius=radius, pctdistance=1-width/2,labels=labels,**kwargs)
    plt.setp( outside, width=width, edgecolor='white')

    kwargs = dict(size=20, fontweight='bold', va='center')
    plt.text(0, 0, text, ha='center', **kwargs)

# Group colors
c1 = (226, 33, 7)
c2 = (60, 121, 189)

# Subgroup colors
d1 = (226, 33, 7)
d2 = (60, 121, 189)
d3 = (25, 25, 25)

make_pie([100, 80, 90], "", [d1, d3, d2], ['M', 'N', 'F'], radius=1.2)
make_pie([180, 90], "", [c1, c2], ['M', 'F'], radius=1)
plt.show()

enter image description here