Upright mu in plot label: retaining original tick fonts

问题

I have a problem which I thought would be more occurring. However, after scouring the internet for some time now I have not been able to find the solution to my problem. So here it goes:

For a plot, created using matplotlib.pyplot I want to incorporate the SI-unit micro meter into my xlabel. The unit micro meter however needs to be upright. After some fiddling around I achieved the desired xlabel.

The code that I have to generate this is:

import matplotlib
import matplotlib.pyplot as plt

matplotlib.rc('text', usetex = True)
params = {'text.latex.preamble': [r'\usepackage{siunitx}', r'\usepackage{cmbright}']}
plt.rcParams.update(params)


fig = plt.figure()
ax = fig.add_subplot(1,1,1)

ax.set_xlabel('$\si{\micro \meter}$', fontsize = 16)
ax.set_ylabel("hi", fontsize = 16)

plt.savefig("test.png")

The result is shown below:

The micro meter is exactly as I want it to be. The problem however is that the font of the x and y ticks is altered. This is because of:

matplotlib.rc('text', usetex = True)

How can I reset the font values to their original values? Or how can I make sure the fonts are not changed when introducing tex?

As a reference, the original values I am referring to look like this:

Besides trying to revert the fonts back to their original values I also tried different methods of incorporating micro meter into my xlabel. The problem that arises here is that I it remains italic or it has a bold type setting. The micro meter I am looking for is the one given in the first figure.

I hope someone can help me solve this problem.

Thanx in advance

回答1:

I am also struggling with such a problem, i.e. getting the tick labels and axes labels to be consistent when text.usetex = True. The solution that I have managed to find it not ideal, but it works for the moment.

What you have to do is set the font family to "sans-serif" and also add a latex package that uses sans-serif math fonts (sfmath -- make sure it is in your tex path!)

import matplotlib
import matplotlib.pyplot as plt

matplotlib.rc('text', usetex = True)
matplotlib.rc('font', **{'family':"sans-serif"})
params = {'text.latex.preamble': [r'\usepackage{siunitx}', 
    r'\usepackage{sfmath}', r'\sisetup{detect-family = true}',
    r'\usepackage{amsmath}']}   
plt.rcParams.update(params)   

fig = plt.figure(figsize = (4,4))
ax = fig.add_subplot(1,1,1)
ax.set_xlabel('$\si{\um} detection$')
ax.set_ylabel(r"$\mu \boldsymbol{\mu}$")
plt.show()

In addition, I had to tell the siunitx package to detect the font family, and I also had to add some additional text to the x-label in order for the detection to actually work (you can remove this text later and the label will still work after that).

For me this results in:

More generally, I have the following my ~/.matplotlib/matploblibrc file, for serif fonts:

font.family    : serif 
text.latex.preamble    :   \usepackage{mathptmx}

and for sans-serif:

font.family : sans-serif 
text.latex.preamble :   \usepackage{sfmath}

回答2:

What worked for me was not to usetex, but to use Unicode:

ax.set_xlabel(u'\u03bc')

sets the label as a single upright mu.

This requires the following settings when loading matplotlib:

import matplotlib
matplotlib.rcParams['mathtext.fontset'] = 'cm'
matplotlib.rc('font', family='serif', serif='CMU Serif')
import matplotlib.pyplot as plt

Here I'm using the "Computer Modern Unicode" font from Sourceforge (highly recommended if you'd like consistency with writing typeset in LaTeX and its default Computer Modern font).

But any unicode font with the mu glyph should work. Actually, the mu from CMU Serif is not as aesthetically nice as the mu from SIunitx, but it is correct.

Python needed to be restarted for that to take effect.