Here is my capstone comparing a few stocks. This should work in realtime to generate the efficient frontier. Had to improvise a few bits since some of the codeacademy tools weren’t available.

Feedback appreciated!

```
import numpy as np
import pandas as pd
import matplotlib as mpl
import matplotlib.pyplot as plt
from yahooquery import Ticker
stocks = ['JPM', 'HD', 'MSFT', 'CVX', 'RNG', 'JNJ']
start_date = '2010-01-01'
end_date = '2020-01-01'
# this selects the stocks to compare and the dates to use
tickers = Ticker(stocks)
df = tickers.history(start=start_date, end=end_date)
pivoted = df.reset_index().pivot(index = 'date', columns = 'symbol', values = 'close')
cov_matrix = pivoted.pct_change().apply(lambda x: np.log(1 + x)).cov()
#for reference: this is the covariance matrix between the selected stocks
e_r = pivoted.resample('Y').last().pct_change().mean()
#here is where we annualize the expected returns
s_d = pivoted.pct_change().apply(lambda x: np.log(1 + x)).std().apply(lambda x: x*np.sqrt(250))
#produces the standard deviations
assets = pd.concat([e_r, s_d], axis = 1)
assets.columns = ['Returns', 'Volatility']
#this produces a table comparing the average returns and their volatility of each stock
p_ret = []
p_vol = []
p_weight = []
num_assets = len(pivoted.columns)
num_port = 1000 # number of portfolio combinations to test
for p in range(num_port):
weights = np.random.random(num_assets)
weights = weights / np.sum(weights)
p_weight.append(weights)
returns = np.dot(weights, e_r)
p_ret.append(returns)
var= cov_matrix.mul(weights, axis = 0).mul(weights, axis = 1).sum().sum()
sd= np.sqrt(var)
ann_sd = sd * np.sqrt(250)
p_vol.append(ann_sd)
#this is how we test for the different combos
data = {'Returns': p_ret, 'Volatility': p_vol}
for counter, symbol in enumerate(pivoted.columns.tolist()):
data[symbol +' weight'] = [w[counter] for w in p_weight]
portfolios = pd.DataFrame(data).sort_values('Returns', ascending = False)
#we can print portfolios to see the list of combination weights and their returns/volatility
portfolios.plot.scatter(x = 'Volatility', y = 'Returns', grid = False)
plt.savefig('plot.png')
print(portfolios.head())
```