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Newbie question about stock universe

Hello,

I've been browsing through the code of some of the algorithms and I would like to understand how the stock universe is set without explicit calls to set_universe. For example if in the initialize method I have a line like,

context.stocks = symbols('SPY')

does that set the stock universe to SPY? Does calling symbols do that under the covers?

Regards,
Mark

1 response

Hi Mark,

Good question! You are correct in that setting context.stocks or context.stock to a symbol/sid or list of symbols/sids will populate your stock universe under the covers. In addition, any orders you make to securities not already in your universe (if you hard coded the order, for example), will be added to your universe. Fetcher can also add securities to your universe. In any given handle_date event, your universe is stored in the data variable so if you're ever in doubt, either log the contents of data or run your algorithm through debugger mode and take a look at the contents of data.

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