Pandas - group by

The dataset contains climate data, the data structure is:

year	month	temp max	temp min	air frost	rain (mm)	hours of sunshine
1948	1	6.6	1.3	8	170.8	40.1

I want to visualise the total hours of sunshine for the summer months (June, July, August) per year. The steps involved in preparing the data were:

1. keep only months 6, 7 and 8
2. drop unnecessary columns
3. group by year and sum

the code:

import pandas as pd
import matplotlib.pyplot as plt
plt.rcParams['figure.figsize'] = [15, 10]

df = pd.read_csv('weather.csv')
print(df.head())
print(df.shape)

months = [6,7,8]
df = df[df['m'].isin(months)]
print(df.head())

drop_cols = ['m','tmax','af','tmin','rainmm']
df = df.drop(drop_cols,axis=1)
print(df.head())

sunh_sum = df.groupby('year').sum()
sunh_sum.plot(kind='bar')
plt.show()


The plot: