import pandas as pd
import quandl
import datetime
import matplotlib.pyplot as plt
import numpy as np
import seaborn as sns
%matplotlib widget
sns.set(palette = 'bright',color_codes=True)

start = datetime.datetime(2010,1,1)
end = datetime.date.today()
quandl.ApiConfig.api_key = "xmMnhixLSRSxxd24G_cU"

a = "AAPL"
aapl = quandl.get("WIKI/" + a, start_date = start, end_date = end)

i = "IBM"
ibm = quandl.get("WIKI/" + i, start_date = start, end_date = end)

am = "AMZN"
amzn = quandl.get("WIKI/" + am, start_date = start, end_date = end)

stocks = pd.concat([aapl['Adj. Close'], ibm['Adj. Close'], amzn['Adj. Close']], axis=1)
log_ret = np.log(stocks/stocks.shift(1))
log_ret = log_ret.dropna()