import pandas as pd

df = pd.read_csv(r"C:\Users\micault.DOMPHILYO1\Documents\Perso\temp.csv", header= None, index_col =1)

df.drop(0, axis=1, inplace=True)
df.columns = ['temp', 'temp_dehors', 'conso_maison']
df.index = pd.to_datetime(df.index)
import numpy as np

df.replace('\N',np.nan, inplace = True)

df.temp.astype('float64')
df.temp = df.temp.astype('float64')
df.temp_dehors = df.temp_dehors.astype('float64')
df.conso_maison = df.conso_maison.astype('float64')

from matplotlib import pyplot as plt

df2 = df.resample("M").mean()

plt.plot_date(df2.index, df2.temp_dehors)
plt.plot_date(df2.index, df2.conso_maison)
plt.show()