from zipline.api import (
    history,
    order_target,
    record,
    symbol,
)


def initialize(context):
    context.i = 0


def handle_data(context, data):
    # Skip first 300 days to get full windows
    context.i += 1
    if context.i < 300:
        return

    # Compute averages
    # history() has to be called with the same params
    # from above and returns a pandas dataframe.
    short_mavg = history(100, '1d', 'price').mean()
    long_mavg = history(300, '1d', 'price').mean()

    sym = symbol('AAPL')

    # Trading logic
    if short_mavg[sym] > long_mavg[sym]:
        # order_target orders as many shares as needed to
        # achieve the desired number of shares.
        order_target(sym, 100)
    elif short_mavg[sym] < long_mavg[sym]:
        order_target(sym, 0)

    # Save values for later inspection
    record(AAPL=data[sym].price,
           short_mavg=short_mavg[sym],
           long_mavg=long_mavg[sym])
add zipline dual moving average example