Скачать или смотреть How to Create an Iterator for a Deck of Cards in Python without Importing Deep Copy

Discover how to generate a card deck iterator in Python using `random` while avoiding common pitfalls like modifying the deck during iteration.
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This video is based on the question https://stackoverflow.com/q/65833694/ asked by the user 'Nissim Levy' ( https://stackoverflow.com/u/11447784/ ) and on the answer https://stackoverflow.com/a/65833855/ provided by the user 'juanpa.arrivillaga' ( https://stackoverflow.com/u/5014455/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Creating a Deck of Cards Iterator in Python

If you're trying to generate an iterator for a deck of cards using Python, you might run into some issues, especially if you're trying to remove cards from the deck while yielding them. One common error developers face is the ValueError: list.remove(x): x not in list. This article will clarify why this happens and how to solve it effectively.

The Problem: Why the Error Occurs

While implementing your card iterator, you may notice that after a few attempts, the program throws an error when you try to remove a card from your deck. This frequently happens because of how you handle the deck and the cards drawn from it.

Key Points to Understand

Type of Output from random.sample: This function returns a list, not a single card. If you try to remove this list from the deck, Python will raise an error because it expects a single element, not a list.

Modifying the Deck During Iteration: Changing the contents of the list you are iterating over can lead to unexpected behavior. If you remove an item from the list while iterating through it, you can accidentally skip elements or try to remove items not present, causing runtime errors.

The Solution: Simplifying Your Card Drawing Logic

Step-by-step Solution

Remove Unnecessary Complexity: Instead of using random.sample to get a card (which gives you a list containing one card), you can simply shuffle the deck first and then yield cards from it sequentially.

Use random.shuffle: This function rearranges the entries in the list in place, effectively randomizing the deck without needing to repeatedly draw and remove cards.

Here's a simplified version of your original function:

[[See Video to Reveal this Text or Code Snippet]]

How It Works

Shuffling: When you call random.shuffle(deck), the initial deck is randomized. You don't need to remove cards, as they are drawn sequentially.

Yielding Cards: Now, in the for loop, you can simply yield card from the shuffled deck until you reach the end, with no risk of modifying the list you are currently iterating over.

Conclusion

Using this method, you can create an iterator for a deck of cards without running into the common issues associated with list modification during iteration. By shuffling the deck first and yielding cards sequentially, you create a robust and clean implementation for card drawing that is both easy to understand and efficient. Happy coding!