Grouping CSV files by month with pandas and time libraries

The phenomenon and background of the problem

About using pandas\time\matplotlib The library will Intel and IBM The average value of the opening price of each month of the company in the past year is drawn in a chart （ use subplot or subplots() function ）

Problem related code , Do not paste screenshots

import pandas as pd
import matplotlib.pyplot as plt
import time

def create_aveg_open(stock_code):
quotesdf_ori=pd.read_csv('step1/'+stock_code+'.csv',index_col=[0])

# Please add the code here , Complete the output as required

Begin

meanopen=quotesdf_ori.groupby('month').open.mean()

End

return meanopen 

def plot():
open1 = create_aveg_open('INTC')
open2 = create_aveg_open('IBM')
plt.figure(figsize=(10,10),dpi=100)

# Please add the code here , Complete the output as required

Begin

x1=open1.indexy1=open1x2=open2.indexy2=open2plt.subplpt(211)plt.plot(x1,y1,color="r",marker="o")plt.subplpt(212)plt.plot(x1,y1,color="g",marker="o")

End

plt.show()plt.savefig( 'step1/outfile/sub.png' )plt.close()

Operation results and error reporting contents

Do not know, such as grouping month

My solution ideas and tried methods

What I want to achieve

Ability to display line charts grouped by month