How to graph from a pandas dataframe

pandasgraphing_2120_a1.py

import pandas as pd  # Use pandas instead to map the data easily
import matplotlib.pyplot as plt  # Use Matplotlib PyPlot to create graph
import numpy as np  # Use Numpy to take mean


def all_temp_plot(filename="London_mean_etr_max_etr_min.csv"):
    # Note: This will not drop years with incomplete datsets.
    # Read CSV, but only 3 columns because no one cares about the other ones
    # then group years, then take mean of months and append it to a new column in a new dataframe.
    df = pd.read_csv(filename, delimiter=',', usecols=[0, 1, 2],
                     names=['Year', 'Month', 'Temperature']).groupby('Year').agg(
        Average_Temperature=pd.NamedAgg(column='Temperature', aggfunc=np.mean))
    # reset the index to have a proper record of records {we just dropped values to do mean}
    df.reset_index(inplace=True, drop=False)
    # rename columns to a human-readable form
    df.columns = ['Year', 'Average Temperature']
    # plot the thing
    df.plot(kind='line', x='Year', y='Average Temperature',
            color='red', title='Average Annual Temperature in London, Ontario')
    # show the plot
    plt.show()


all_temp_plot()