Calculate monthly and quarterly Apple (aapl) security returns

appl_returns.py

import pandas_datareader as pdr
import datetime

aapl = pdr.get_data_yahoo('AAPL',
                          start=datetime.datetime(2007, 1, 1),
                          end=datetime.datetime(2018, 1, 1))

# resample 'aapl' to business months, take last observation
monthly = aapl.resample('BM').apply(lambda x: x[-1])

# calculate the monthly percentage change
print(monthly.Close.pct_change())

# resample 'aapl' to quarters, take the mean as value per quarter
quarter = aapl.resample('4M').mean()

# calculate the quarterly percentage change
print(quarter.Close.pct_change())