Скачать или смотреть How to Store Values from a List and Dictionary in Python Efficiently

Discover how to resolve issues with storing tickers from a list and dictionary in Python using the Alpaca API. Step-by-step guide to effective coding solutions!
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This video is based on the question https://stackoverflow.com/q/62414152/ asked by the user 'FM2020' ( https://stackoverflow.com/u/13330901/ ) and on the answer https://stackoverflow.com/a/62414376/ provided by the user 'Peilonrayz' ( https://stackoverflow.com/u/2044866/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Storing Values from a List and Dictionary in Python: A Practical Solution

When working with data in Python, especially in financial contexts such as fetching assets from an API, it is common to encounter issues related to storing and filtering values. A frequent situation arises when trying to match entries from a filtered list with a corresponding dictionary. This guide aims to address the problem faced by many coders when dealing with the Alpaca API and how to efficiently store tickers that exist in both a list and a dictionary.

The Problem

You are attempting to filter tickers from a list of assets that are shortable based on the Alpaca API. Specifically, you have a dictionary called symbol_list that contains a set of ticker symbols, and you want to check which of those symbols are present in a filtered list called shortable_marginable_assets. However, upon running your code, you noticed that the variable final_universe_tickers remains empty.

Understanding the Issue

The main issue stems from where your loops are positioned. You are currently only looping through the last value of final_universe, which leads to empty results in your final_universe_tickers. To remedy this, you need to ensure the values are appended within each iteration of the loops, rather than outside.

The Solution

To resolve this issue, you need to restructure your loops. Specifically, you should nest the loop that processes the final_universe within the loop that iterates over symbol_list. Here’s a step-by-step breakdown of how to adjust your code:

1. Initialize an Empty List

First, ensure that final_universe_tickers is initialized as an empty list before beginning the loops.

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2. Loop Through symbol_list

Next, iterate over each symbol in symbol_list. Inside this loop, filter the shortable_marginable_assets to create the final_universe, which contains only the assets matching the current symbol from the dictionary.

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3. Append Symbols to the List

Now, you need to move the loop that appends the symbol to the final_universe_tickers inside the same loop as symbol. This way, you will collect all matching tickers during each iteration.

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4. Full Code

Here's how your complete code should look after making these adjustments:

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Conclusion

By making these simple adjustments to the code structure, you ensure that you're storing the tickers correctly, gathering all entries that exist in both your filtered asset list and your dictionary. This method not only resolves the issue you encountered but also reinforces the importance of carefully structuring loops to harness the power of Python effectively.

Happy coding! If you have further questions or issues, feel free to reach out, and let’s tackle them together!