Hi,
I'm looking at Lean as a possible home backtesting framework. From the framework I've seen, they fall into 2 categories - either they use pandas/numpy (and associated libraries) or they code everything themselves. I come from a Matlab background and at the moment I use pandas/numpy for backtesting.
From what I can see Lean falls into the second category. Is it possible however, to use pandas/numpy etc. when writing backtests in python? Do you have any examples?
Alexandre Catarino
It is possible, yes.
Moreover, when you make a historical data request, the method return a pandas.DataFrame:
# Get history in pandas.DataFrame format, use list of string df = self.History(["EURUSD"], timedelta(7)) df = self.History(["EURUSD"], timedelta(7), Resolution.Minute) df = self.History(["EURUSD"], 14) df = self.History(["EURUSD"], 14, Resolution.Minute)
Richard Shoemake
Alexandre,
Do you recommend then that we just get a history dataframe at initialiation and then add to it as the data comes in? It seems that is the only way to get a true pandas dataframe.
Alexandre Catarino
We recommend not making historical data requests on every data event (every time step).
You can make one historical request at Initialize and add to is as data comes in if you need an updated data frame on every time step. However, if you just need an updated data frame once a day, for example, when the market opens, it may be simpler to just make the history when you need it.
Richard Shoemake
Jack Simonson
Hi Richard,
While we don't have versions of indicators that accept dataframes, it is possible to create custom indicators that would accept a dataframe and can mimic the same behavior as QuantConnect indicators. You can find documentation for custom indicators in C# (https://www.quantconnect.com/lean/documentation/topic15.html) and in Python here.
Alpha
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