设置“matplotlib.rcParams['text.usetex'] = True”以在标签中使用LaTeX并使用德语语言环境使用逗号时的Python图形问题

Question

I want to create figures in which the x and y tick labels show their numerical values properly formatted for the German language, ie, using the comma as the decimal separator. I also want to LaTeX elements eg in the x or y axis label or the plot legend. The following code shows that the first figure is created as desired for the English language version.

# -*- coding: utf-8 -*-
import numpy as np
import matplotlib
import matplotlib.pyplot as plt

import locale

#  Set to German locale to get comma decimal separater
locale.setlocale(locale.LC_NUMERIC, "deu_deu")

# Use LaTeX elements
matplotlib.rcParams['text.usetex'] = True

t = np.linspace(0.0, 1.0, 100)
s = t*np.cos(4 * np.pi * t) + 2

fig, ax = plt.subplots(figsize=(6, 4))
ax.plot(t, s)

ax.set_xlabel(r'Time $t$ with $t \le 1$')
ax.set_ylabel('Velocity $v(t)$')

plt.show()

fig.savefig("Mein_Test1.pdf")


fig2, ax2 = plt.subplots(figsize=(6, 4))
ax2.plot(t, s)

ax2.set_xlabel(r'Time $t$ with $t \le 1$')
ax2.set_ylabel('Velocity $v(t)$')

plt.ticklabel_format(useLocale=True)

plt.show()

fig2.savefig("Mein_Test2.pdf")

The first figure looks as desired, with nice English points as decimal separators and nice spacing in the axis tick labels, and I can use the LaTeX "\\le" symbol in the x axix label:

However, the second figure shows an ugly spacing in the numbers of axis tick labels, with too much space behind the decimal separator:

If I do not use "matplotlib.rcParams['text.usetex'] = True", then I cannot have the LaTeX elements in the label, ie, no "\\le" symbol, but then the spacing is correct even for the German commas. So there seems to be some conflict here between the German locale and the "text.usetex". Any ideas to get both right? Thanks!

Answer 1

I eventually found a way to achieve the desired result by looking at the answer to this question, using also lambda function. Here is the code:

# -*- coding: utf-8 -*-
import numpy as np
import matplotlib as mpl
import matplotlib.pyplot as plt

import locale

# Set to German locale to get comma decimal separater
locale.setlocale(locale.LC_NUMERIC, "deu_deu")

# Use LaTeX elements
mpl.rcParams['text.usetex'] = True

t = np.linspace(0.0, 1.0, 100)
s = t*np.cos(4 * np.pi * t) + 2

fig2, ax2 = plt.subplots(figsize=(6, 4))

ax2.ticklabel_format(useLocale=True)

ax2.plot(t, s)

ax2.set_xlabel(r'Time $t$ with $t \le 1$')
ax2.set_ylabel('Velocity $v(t)$')

plt.ticklabel_format(useLocale=True)


ax2.get_yaxis().set_major_formatter(mpl.ticker.FuncFormatter(lambda x, loc: locale.format_string('%1.3f', x, 1)))
ax2.get_xaxis().set_major_formatter(mpl.ticker.FuncFormatter(lambda x, loc: locale.format_string('%0.2f', x, 2)))

plt.show()

fig2.savefig("Mein_Test2.png")

Now I get the desired result: