How to use backtrader built-in indicator like a 'normal' indicator?

[weibudda]

When I use backtrader built-in indicator out-of backtrader environment,

a = bt.indicators.EMA(datas.close, period=13)

it returns a <backtrader.indicators.ema.EMA at 0x1af69d08> object, with data lengtn of 0
How to get a normal data array like datas.close, instead of an empty object?

[rajanprabu]

@weibudda

This could help.

https://www.backtrader.com/docu/concepts/#getting-a-slice