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pythonlistalpaca

How to comprehend and collect a value from a complex list using the Alpaca API?

request_close = StockLatestTradeRequest(symbol_or_symbols = "TSLA", start = datetime.now(), timeframe = TimeFrame.Minute, limit = 1) 
price = [{x['p']} for x in data_client.get_stock_latest_trade(request_close)["TSLA"]][0].pop()
print(price)

I'm trying to use a different method in the alpaca API as seen above, but it doesn't work because the output is different. How am I supposed to format it?

I tried doing this to comprehend the list:

price = [{x['p']} for x in data_client.get_stock_latest_trade(request_close)["TSLA"]][0].pop()
print(price)

But the code doesn't work for the specific output that the get_stock_latest_trade has.

Solution

  • Lets look at the return types of the two functions you reference:

    get_stock_bars() has a return type of Union[BarSet, RawData]. And if we look further, a BarSet is Dict[str, List[Bar]]

    So your code works because you access the value associated with the "TSLA" key in the dictionary. That value you accessed is a list, so you are able to access the first item of that list.

    get_stock_latest_trade() has a return type of Union[Dict[str, Trade], RawData]. If we look further, we can see that a Trade is just a dictionary of values. All you need to do is use the 'p' key to access the price value.

    For your code to work:

    request_close = StockLatestTradeRequest(symbol_or_symbols="TSLA")
price = data_client.get_stock_latest_trade(request_close)["TSLA"]['p']
print(price)

    Another note: StockLatestTradeRequest only has two parameters:

    • symbol_or_symbols (which is required)
    • feed (which is optional)

    So I am not sure why you had there was a start, timeframe, and limit parameters when you wrote the code.

    References: https://github.com/alpacahq/alpaca-py/