[PYTHON] Make common settings with subplot of matplotlib

Thing you want to do

I want to make common settings such as grids and labels for all axes drawn with matplotlib subplot.

Method 1

1. Get a list of axes.
2. Loop for each axis
3. Change the current axis

# 1.Get a list of axes
axs = plt.gcf().get_axes()

# 2.Loop for each axis
for ax in axs:
    # 3.Change current axis
    plt.axes(ax)

Code example

import matplotlib.pyplot as plt
import numpy as np

#data
x  = np.linspace(-np.pi, np.pi, 100)
y1 = np.sin(x)
y2 = np.cos(x)

# figure
plt.figure(figsize=(8,4))

#Plot 1
plt.subplot(1,2,1)
plt.plot(x,y1,label='sin')

#Plot 2
plt.subplot(1,2,2)
plt.plot(x,y2,label='cos')

#Get a list of axes
axs = plt.gcf().get_axes()

#Loop for each axis
for ax in axs:
    #Change current axis
    plt.axes(ax)

    #Show legend
    plt.legend(loc=2)

    #grid
    plt.grid(linestyle='--')

    #Axis label
    plt.xlabel('x')
    plt.ylabel('y')

    #Axis range
    plt.xlim([-np.pi, np.pi])
    plt.ylim([  -1.2,   1.2])

#Adjustment of figure
plt.tight_layout()

Method 2

1. List data and labels.
2. Loop using enumerate
3. Don't forget to add +1 to plt.subplot

# 1.List data and labels.
Y    = [y1, y2]
lbls = ['sin', 'cos']

# 2.Loop with enumerate
for i, y in enumerate(Y):

    # 3. plt.subplot is+Don't forget to
    plt.subplot(1,2,i+1)

Code example 2

# figure
plt.figure(figsize=(8,4))
# list
Y    = [y1, y2]
lbls = ['sin', 'cos']

for i, y in enumerate(Y):
    #Subplot
    plt.subplot(1,2,i+1)
    
    #plot
    plt.plot(x,y,label=lbls[i])

    #Show legend
    plt.legend(loc=2)

    #grid
    plt.grid(linestyle='--')

    #Axis label
    plt.xlabel('x')
    plt.ylabel('y')

    #Axis range
    plt.xlim([-np.pi, np.pi])
    plt.ylim([  -1.2,   1.2])

#Adjustment of figure
plt.tight_layout()

The following supplementary information

gca, gcf You can get the current figure with plt.gcf () and the current axes with plt.gca (). You can also specify the current axis with plt.axes ().

Hierarchical structure

Like MATLAB, matplotlib's figure has a hierarchical structure as shown in the figure below.

There are axes in the figure and lines in the axes. You can get a list of all the axes in the current figure with plt.gcf (). get_axes (). Besides, plt.gca (). get_lines () can get all the lines in the current axes.