Python Matplotlib: How do I save (in pdf) all the graphs I create in a loop?

[JaneTan]

Hi,

Refer to the entire code appended at the end. Thanks

1) I meet with "Cannot assign to operator (pyflakes E)" when I try to assign a variable(j) to the name of another variable

'fig' + str(j), 'ax' + str(j) = plt.subplots()

2) How can I create a loop to save all the plots I created in the loop to a single pdf file?
Thank you

import xlrd
import openpyxl
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.backends.backend_pdf import PdfPages
file_location = "C:/Users/Desktop/Sample1.xlsx"

j=0
wb = xlrd.open_workbook(file_location)
ws = wb.sheet_by_index(0)


x1 = [int(ws.cell_value(i, 0)) for i in range(1,ws.nrows)]
x2 = [int(ws.cell_value(i, 0)) for i in range((ws.nrows-10),ws.nrows)]

for col in range(1,ws.ncols,4):
    j+=j

    y1 = [ws.cell_value(i, col) for i in range(1,ws.nrows)]
    #plt.figure(0)

    'fig' + str(j), 'ax' + str(j) = plt.subplots()
    
    'ax'+str(j).plot(x1, y1)

pp = PdfPages('C:/Users/Desktop/Sample1.pdf')
pp.savefig(fig1)
pp.savefig(fig2)
pp.close()
    
del pp

[Larz60+]

Here's a simple example:

import matplotlib.pyplot as plt
import numpy as np

np.random.seed(19680801)
data = np.random.randn(2, 100)

fig, axs = plt.subplots(2, 2, figsize=(5, 5))
axs[0, 0].hist(data[0])
axs[1, 0].scatter(data[0], data[1])
axs[0, 1].plot(data[0], data[1])
axs[1, 1].hist2d(data[0], data[1])

plt.show()
plt.savefig("mypdf.pdf")