Matplotlib graph with multiple y axis shows and doesn't save

Question

I am plotting a graph with 3 y axis, and it shows in the plot window of Spyder instead of saving correctly in a folder. The graph saved in a folder is blank. Here's my code :

fig, ax1 = plt.subplots()
ax2 = ax1.twinx()
ax3 = ax1.twinx()
plt.figure(figsize = (121, 75))

ax1.set_xlabel('time(s)')
ax1.set_ylabel('y1')
ax2.set_ylabel('y2')
ax3.set_ylabel('y3')
rspine = ax3.spines['right']
rspine.set_position(('axes', 1.15))
plt.xticks(fontsize=50)
plt.yticks(fontsize=50)
ax1.plot(fd[fd.columns[0]], fd[fd.columns[1]], color = 'r', linewidth = 2)
ax2.plot(fd[fd.columns[0]], fd[fd.columns[2]], color = 'g', linewidth = 2)
ax3.plot(fd[fd.columns[0]], fd[fd.columns[3]], color = 'b', linewidth = 2)
ax3.legend([ax1.get_lines()[0], ax2.get_lines()[0], ax3.get_lines()[0]], ['y1', 'y2', 'y3'])
plt.savefig(folder+"/"+str(file_name)+"y1/2/3.png")
plt.close()

Am I doing something wrong here ? I don't call the show() function so I don't understand why the graph shows anyway (when plotting the 3 y axis on the same graph with only using plt.figure(), plt.plot() then plt.save() and close(), it works as intended)

Edit : What I want is to have the graph saved correctly in my folder, with the size I set in plt.figure(), which isn't the case now.

Answer 1

I found what went wrong : I stead of writing fig = plt.figure(figsize=(121, 75)) fig, ax1 = plt.subplots(), I had to write fig, ax1 = plt.subplots(figsize=(121, 75)) The graph then plots at the size indicated, and doesn't shows in the window of Spyder.

Answer 2

You can use set_size_inches before saving the figure. dpi feature can be use to increase the resolution of the figure also.

import matplotlib.pyplot as plt
import numpy as np

plt.rcParams['font.size'] = '50'

fig = plt.figure(figsize=(121, 75), dpi=200)
fig, ax1 = plt.subplots()
ax2 = ax1.twinx()
ax3 = ax1.twinx()
ax1.set_xlabel('time(s)')
ax1.set_ylabel('y1')
ax2.set_ylabel('y2')
ax3.set_ylabel('y3')
rspine = ax3.spines['right']
rspine.set_position(('axes', 1.05))
rspine2 = ax2.spines['right']
rspine2.set_position(('axes', 1.0))
# plt.xticks(fontsize=50)
# plt.yticks(fontsize=50)
ax1.plot(np.arange(100), np.random.rand(100), color='r', linewidth=2)
ax2.plot(np.arange(100), np.random.rand(100), color='g', linewidth=2)
ax3.plot(np.arange(100), np.random.rand(100), color='b', linewidth=2)
ax3.legend([ax1.get_lines()[0], ax2.get_lines()[0], ax3.get_lines()[0]], ['y1', 'y2', 'y3'])
# fig.tight_layout()
figure = plt.gcf()
figure.set_size_inches(121, 75)
plt.savefig("3.png", dpi=None)
plt.close()