how i want buy at a and sell at b

[hy2014]

see the '' signal = data > sma '' in example, but if i have a indicator, when indicator < 10, i buy it; indicator > 50, sold it.
how to implement this example.

[Matoran]

from https://pmorissette.github.io/bt/examples.html#sma-crossover-strategy

## download some data & calc SMAs
data = bt.get('spy', start='2010-01-01')
sma50 = data.rolling(50).mean()
sma200 = data.rolling(200).mean()

## now we need to calculate our target weight DataFrame
# first we will copy the sma200 DataFrame since our weights will have the same strucutre
tw = sma200.copy()
# set appropriate target weights
tw[sma50 > sma200] = 1.0
tw[sma50 <= sma200] = -1.0
# here we will set the weight to 0 - this is because the sma200 needs 200 data points before
# calculating its first point. Therefore, it will start with a bunch of nulls (NaNs).
tw[sma200.isnull()] = 0.0