Arithmetic operations

import numpy as np

def test_run():
	a = np.array([(1, 2, 3, 4, 5),(10, 20, 30, 40, 50)])
	print "Original array a:\n", a

	print "\nMultiply a by 2:\n", 2 * a

if __name__ == "__main__":
	test_run()

Rolling statistics is buying opportunity
rolling standard dev

def test_run():
	dates = pd.date_range('2012-01-01','2012-12-31')
	symbols = ['SPY']
	df = get_data(symbols, dates)

	ax = df['SPY'].plot(title="SPY rolling mean", label='SPY')

	rm_SPY = pd.rolling_mean(df['SPY'], window=20)

	rm_SPY.plot(label='Rolling mean', ax=ax)