Different font sizes in the same annotation of matplotlib

Question

I need to annotate a pylab rectangle with few data lines - which are of different length. Searching through the matplotlib documentation, and Googling, I could not find a way to give different parts of an annotation different sizes.

The following snippet demonstrates the problem:

import pylab
from matplotlib.patches import Rectangle
pylab.rcParams['verbose.level'] = 'debug-annoying' 

def draw_rectangle(lower, upper, entry):
    ax = pylab.subplot(111)
    r = Rectangle( lower, upper[0]-lower[0], upper[1] - lower[1],
            edgecolor='k')
    ax.add_patch(r)

    textRank = str(entry['rank'])
    textTeamName = entry['teamName']
    textSubmissionDate = entry['submissionDate']
    text = textRank + "\n" + textTeamName + "\n" + textSubmissionDate

    ax.add_artist(r)
    rx, ry = r.get_xy()
    cx = rx + r.get_width()/2.0
    cy = ry + r.get_height()/2.0

    ax.annotate(text, (cx, cy), color='w', weight='bold', ha='center', va='center', size=14)

if __name__ == '__main__':
    entry = {'rank': 22, 'submissionDate': '12/21/2012 4:58:45 AM', 'teamName': 'A very very very very very very very very very very long name'}
    lower = [0,0]
    upper = [1,1]
    draw_rectangle(lower, upper, entry)
    pylab.show()

E.g., is there a way to have the annotation where the font size of 'teamName' is different than the font size of 'rank'?

Another problem is I could not find a way for the font size to correlate to the zooming:

I'm creating a treemap plot, namely, the pylab window is filled with different sized rectangles. If I want to create annotations for the different rectangles, the long data need to be of very small size (to stay within the respective rectangles' boundaries). However, I'd like the font size of the long data line to grow as I zoom in.

Bertil Johannes Ipsen · Answer 1 · 2020-11-25T14:35:16.717

52

Make your plot first, then use ax.annotate, iterating over your x coordinates, y coordinates, labels and fontsizes.

import matplotlib.pyplot as plt

X = [1,2,3,4,5]
Y = [1,1,1,1,1]
labels = 'ABCDE'
sizes = [10, 15, 20, 25, 30]

fig, ax = plt.subplots()

ax.scatter(X, Y)

for x, y, label, size in zip(X, Y, labels, sizes):
    ax.annotate(label, (x, y), fontsize=size)

plt.show()

edited Nov 25 '20 at 14:35

answered Aug 17 '20 at 11:13

Bertil Johannes Ipsen

1,656
1
14
27

score 4 · Answer 2 · answered Feb 02 '13 at 07:55

4

I couldn't find a way to create an annotation with different fonts, so I'll create a helper function that will calculate the font weight to use on each line of the annotation, with the relevant (cx, cy),
and then call ax.annotate several times.

answered Feb 02 '13 at 07:55

user1850727

569
2
6
9

12

Would you share it ? :-) – pierre Feb 03 '15 at 08:27

cottontail · Answer 3 · 2023-05-16T04:57:29.273

Annotations are stored in ax.texts, which is a list of Annotation objects. Annotation objects define a set_size() method, which can be called if the fontsize of a specific annotation needs to be changed after the plot is made.

This is especially useful if the plot with the annotations are created using an external library such as scikit-learn, statsmodels etc.

import matplotlib.pyplot as plt

X, Y, labels = [1,2,3,4,5], [1]*5, 'ABCDE'
sizes = [10, 15, 20, 25, 30]

# scatter plot with annotations
plt.scatter(X, Y)
for x, y, label in zip(X, Y, labels):
    plt.annotate(label, (x, y))

# change annotation fontsizes
ax = plt.gca()
for a, size in zip(ax.texts, sizes):
    a.set_size(size)

Different font sizes in the same annotation of matplotlib

3 Answers3