Matplotlib pdf Output - pandas

Question

Im new to matplotlib and wont to use the graphics in Latex.
There ist a visual output as a graphic but:
Why is there no pdf output?
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import os #to remove a file
import datetime
from matplotlib.backends.backend_pdf import PdfPages
#######################
Val1 = [1,2,3,4,5,6,7,8,9,9,5,5] # in kWh
Val2 = [159,77,1.716246,2,4,73,128,289,372,347,354,302] #in m³
index = ['Apr', 'Mai', 'Jun', 'Jul','Aug','Sep','Okt','Nov','Dez','Jan', 'Feb', 'Mrz']
df = pd.DataFrame({'Val1': Val1,'Val2': Val2}, index=index)
with PdfPages('aas2s.pdf') as pdf:
plt.rc('text', usetex=True)
params = {'text.latex.preamble' : [r'\usepackage{siunitx}', r'\usepackage{amsmath}']}
plt.rcParams['font.family'] = 'serif'
plt.rcParams['font.serif'] = 'Liberation'
plt.rcParams.update(params)
plt.figure(figsize=(8, 6))
plt.rcParams.update({'font.size': 12})
ax = df[['Val1','Val2']].plot.bar(color=['navy','maroon'])
plt.xlabel('X Achse m')
plt.ylabel('Y Achse Taxi quer ')
plt.legend(loc='upper left', frameon=False)
plt.title('Franz jagt im komplett verwahrlosten Taxi quer durch Bayern')
plt.show()
pdf.savefig()
plt.close()
The error is called: ValueError: No such figure: None
And how do i get a second "Y" axis for the second value?

Answer 1

In general, savefig should be called before show. See e.g.
Matplotlib (pyplot) savefig outputs blank image
How come pyplot from Matplotlib doesn't allow you to save an image after you show it? (with some more explanation)
Second, you want to produce the plot inside the created figure, not create a new one, hence use
fig, ax = plt.subplots(figsize=...)
df.plot(..., ax=ax)
and later call the methods of the axes (object-oriented style).
In total,
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.backends.backend_pdf import PdfPages
#######################
Val1 = [1,2,3,4,5,6,7,8,9,9,5,5] # in kWh
Val2 = [159,77,1.716246,2,4,73,128,289,372,347,354,302] #in m³
index = ['Apr', 'Mai', 'Jun', 'Jul','Aug','Sep','Okt','Nov','Dez','Jan', 'Feb', 'Mrz']
df = pd.DataFrame({'Val1': Val1,'Val2': Val2}, index=index)
with PdfPages('aas2s.pdf') as pdf:
plt.rc('text', usetex=True)
params = {'text.latex.preamble' : [r'\usepackage{siunitx}', r'\usepackage{amsmath}']}
plt.rcParams['font.family'] = 'serif'
plt.rcParams['font.serif'] = 'Times New Roman'
plt.rcParams.update(params)
fig, ax = plt.subplots(figsize=(8, 6))
plt.rcParams.update({'font.size': 12})
df[['Val1','Val2']].plot.bar(color=['navy','maroon'], ax=ax)
ax.set_xlabel('X Achse m')
ax.set_ylabel('Y Achse Taxi quer ')
ax.legend(loc='upper left', frameon=False)
ax.set_title('Franz jagt im komplett verwahrlosten Taxi quer durch Bayern')
pdf.savefig()
plt.show()
plt.close()
Now if you still need to save the figure after is it being shown, you can do so by specifically using it as argument to savefig
plt.show()
pdf.savefig(fig)