Bollinger Bands

[akitxu]

I propose this change
def bollinger_bands(self, df, n): """ :param df: pandas.DataFrame :param n: :return: pandas.DataFrame """ sma = data.rolling(window = n).mean() std = data.rolling(window = n).std() upper_bb = sma + std * 2 lower_bb = sma - std * 2 return upper_bb, lower_bb