CODEWITHSUNDEEP
pythonpandasmatplotlibspecial-characters
Jb Drucker
Jb Drucker

Reputation: 992

Crashing matplotlib with special chars in strings

matplotlib crashes when a Pandas Serie contains specific special chars in a string, in my case $$.

import matplotlib.pyplot as plt
import random
import pandas as pd
list_= 'abcdefghijklmnopqrstuvwxyz'

l = pd.Series()
for i in range(0,100):
    l[i] = random.choice(list_)
l[50] = '$$'
l.value_counts(normalize=False).plot(kind='bar')
plt.show()

This code will crash due to the l[50] = '$$' line.

Question: am I expected to clean such strings beforehand, or is it a bug in matplotlib?

I'm fairly new to using python for data science, so bear with my naive approach.
Thanks

EDIT: thanks to @mozway and @chrslg for their answers, $$ is indeed interpreted as Latex by matplotlib and it raises an error because there's nothing between the two $ signs.

Having no control over the data I'm plotting, I've opted to deactivate the parsing of Latex by matplotlib like so:
plt.rcParams['text.parse_math'] = False

Upvotes: 0

Views: 55

Answers (2)

mozway
mozway

Reputation: 262204

You need to escape the $ as it will be interpreted as LaTeX formatting (specifically, $...$ is the LaTeX math mode, which is useful if you want to type complex mathematical terms, try for instance l[49] = r'$x_1 \cdot \delta t$'):

l[50] = r'\$\$'
l.value_counts(normalize=False).plot(kind='bar')

Output:

enter image description here

Upvotes: 5

chrslg
chrslg

Reputation: 13491

$$ is the beginning of a LaTeX math formula. So matplotlib crashes because you have a math formula opened and not closed.

Note that it did not crashes, strictly speaking. It correctly raises an error (it is not as if it broke the python interpreter with a segfault). The error message (that you should have included in your question) clearly states

ParseException: Expected end of text, found '$'  (at char 0), (line:1, col:1)

(Well, not that clearly. But that is a very classical error for many parsers: it complains about what it expected)

Upvotes: 2

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