Labels alignmnet pie chart / matplotlib 2.1.0+

Question

I am having a question regarding a pie-chart labels alignment. I'd like to have labels outside the pie-chart and centered to each wedge. According to the documentation page, "labeldistance" parameter enables to place labels outside the pie-chart, and "ha" & "va" parameters supposed to center. However, these two options (ha & va) seems not working on Matplotlib v2.1.0+. 1) With this example (pls see below), you can see that "car" label is not centered properly, it is a bit off the center.

import matplotlib.pyplot as plt
figure = plt.figure()
axes = figure.add_subplot(111)
axes.set_aspect(1)  # circular pie
y = [1,2,3, 4,8,16,18]
label = ['car','domino', 'romancical','testing1', 'thisisthelonglabel', 
         'fffffffffffffffffffffffffffffffffffffffffff', 'as']
wedges, texts = plt.pie(y, 
                        radius=1.2, 
                        labels=label, 
                        labeldistance=1.0, 
                        rotatelabels =True,
                        startangle = 10,
                        wedgeprops = {"linewidth": 0.7, 
                                      "edgecolor": "white"},
                        textprops = dict(ha="center", 
                                          va="center")) # doesn't work 
plt.show()

I added the following lines to force labels to be centered, which works but disabled "labeldistance" parameter. So all my centered correctly, as I want labels are overlapping with the pie-chart circle.

    wedges, texts = plt.pie(y, 
                            radius=1.2, 
                            labels=label, 
                            labeldistance=1.0, 
                            rotatelabels =True,
                            startangle = 10,
                            wedgeprops = {"linewidth": 0.7, 
                                          "edgecolor": "white"},
                            textprops = dict(ha="center", 
                                              va="center"))
for t in texts:
       t.set_horizontalalignment("center")
       t.set_verticalalignment("center")
 plt.show()

So my question is, do "ha" & "va" options work for other users? And could anyone advice if there is a solution for keeping "labeldistance" while using .set_horizontalalignment("center") and set_verticalalignment("center") ?

Thank you.

You are setting both horizontal and vertical alignments to 'center', but what you want is to only set the vertical alignment to 'center'. In other words, remove the lines ha="center" and t.set_horizontalalignment("center"). If anything, set the horizontal alignment to 'left'. — Thomas Kühn
For me, on 2.2.2, both your codes generate the second figure — Sheldore
@ThomasKühn: Hiding ha or setting it to left also doesn't seem to work — Sheldore

ImportanceOfBeingErnest ImportanceOfBeingErnest · Accepted Answer · 2019-01-30T13:57:36

In matplotlib 3.0.2 as well as 2.1.2, using

textprops = dict(va="center", rotation_mode = 'anchor')

(and labeldistance=1.05) results in

Note that this leaves out the ha="center" option, because the horizontal alignment is best be automatically set depending on if the label is on the left or right side of the circle.

For an explanation of rotation_mode see e.g. this question or this question.

Labels alignmnet pie chart / matplotlib 2.1.0+

1 Answers