Change matplotlib polar plot radial axis label fonts

I tried to create two polar scatter plots, one being a zoom-in of the other. I have no problem configuring the font properties of the angular axis, but my attempts to change the fonts of the radial axis have not been successful.

I have tried using the font_manager to define the font:

import matplotlib.pyplot as plt
import numpy as np
from matplotlib.font_manager import FontProperties

#define font
baseFont = FontProperties(family='Helvetica',fname=[path to the .ttf file])

a = np.random.uniform(-np.pi/2,np.pi/2,100)
d = np.random.uniform(0,20,100)
c = np.random.uniform(0,1,100)

fig, sub = plt.subplots(1,2,subplot_kw={'polar':[True,True]})

#configure the ticks
aTicks = np.linspace(-np.pi/2,np.pi/2,7,endpoint=True)
aLabels = np.linspace(-90,90,7,endpoint=True)
dTicks1 = np.arange(0,20.1,5)
dTicks2 = np.arange(0,5.1,1)

#plot the first graph
sub[0].scatter(a,d,c=c,cmap='hsv')

sub[0].set_thetamin(-90)
sub[0].set_thetamax(90)
sub[0].set_ylim(0,20.1)
sub[0].set_xticks(aTicks,labels=aLabels,font=baseFont,fontsize=12)
sub[0].set_yticks(dTicks1,labels=dTicks1,font=baseFont,fontsize=12)

sub[1].scatter(a,d,c=c,cmap='hsv')

sub[1].set_thetamin(-90)
sub[1].set_thetamax(90)
sub[1].set_ylim(0,5.1)
sub[1].set_xticks(aTicks,labels=aLabels,font=baseFont,fontsize=12)
sub[1].set_yticks(dTicks2,labels=dTicks2,font=baseFont,fontsize=12)

plt.show()

The angular axis tick font is changed to Helvetica, while the radial axis tick font remains the default font.

I have also tried changing the tick densities and confirm that sub[0].set_yticks() can affect the radial axis tick marks, but the only thing that does not change is the tick label font. The resulting image is attached.

Plot result

Solution

Here is the working code:

import matplotlib.pyplot as plt
import numpy as np
# import global font_manager
from matplotlib import font_manager

# add the custom font to the global font manager (don't create an instance)
font_manager.fontManager.addfont('Jersey15.ttf')  # font ttf file path
# in this case 'Jersey15.ttf' has a font family 'Jersey 15' (note the name, I think you got it already)

a = np.random.uniform(-np.pi / 2, np.pi / 2, 100)
d = np.random.uniform(0, 20, 100)
c = np.random.uniform(0, 1, 100)

fig, sub = plt.subplots(1, 2, subplot_kw={'polar': [True, True]})

# configure the ticks
aTicks = np.linspace(-np.pi / 2, np.pi / 2, 7, endpoint=True)
aLabels = np.linspace(-90, 90, 7, endpoint=True)
dTicks1 = np.arange(0, 20.1, 5)
dTicks2 = np.arange(0, 5.1, 1)

# plot the first graph
sub[0].scatter(a, d, c=c, cmap='hsv')

sub[0].set_thetamin(-90)
sub[0].set_thetamax(90)
sub[0].set_ylim(0, 20.1)
sub[0].set_xticks(aTicks, labels=aLabels)
sub[0].set_yticks(dTicks1, labels=dTicks1)
# use the `font_manager.FontProperties(fontname).get_name()` for the font family (i.e. 'Jersey 15' or 'Bernard MT 
# Condensed')
sub[0].tick_params(labelfontfamily=font_manager.FontProperties("Jersey 15").get_name(), labelsize=20)
# or, you can use the name for the font family directly also
# sub[1].tick_params(labelfontfamily="Jersey 15", labelsize=12)

sub[1].scatter(a, d, c=c, cmap='hsv')

sub[1].set_thetamin(-90)
sub[1].set_thetamax(90)
sub[1].set_ylim(0, 5.1)
sub[1].set_xticks(aTicks, labels=aLabels)
sub[1].set_yticks(dTicks2, labels=dTicks2)
# you can use the name for the font family directly also
sub[1].tick_params(labelfontfamily="Jersey 15", labelsize=12)

plt.show()

This produces the following output:

Jersey 15	Helvetica

To check the fonts available you can use font_manager.get_font_names().

I think this will point you in right direction. I have attached the links I read to get the idea below please refer to those if you want to learn more.