r/PythonLearning • u/Sea-Ad7805 • 9d ago

Python Data Model Exercise

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An exercise to help build the right mental model for Python data. - Solution - Explanation - More exercises

The โ€œSolutionโ€ link visualizes execution and reveals whatโ€™s actually happening using ๐—บ๐—ฒ๐—บ๐—ผ๐—ฟ๐˜†_๐—ด๐—ฟ๐—ฎ๐—ฝ๐—ต.

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u/ghost59 9d ago

That's weird. Why is it printing C when a didn't touch again.

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u/Sea-Ad7805 9d ago

See the "Explanation" link for an explanation of Python's data model.

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u/ghost59 9d ago

Oh! Wait. I'm stupid. You didn't make a copy of the values with b. You copied the original and when you change b you mutate a as well. It's because the list is something that can be mutated.

If I wanted a not to mutate. It would need to be B = a.copy()

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u/Sea-Ad7805 9d ago

Be careful, b = a.copy() makes a shallow copy. Are you sure you want that? https://github.com/bterwijn/memory_graph?tab=readme-ov-file#copying-values-of-mutable-type

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u/ghost59 9d ago

No. I want a deep copy. Because you're right. Looks like I'll be hitting training grounds on boot.dev tonight.

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u/Sea-Ad7805 9d ago edited 9d ago

I tried to make the exercise difficult so don't feel bad. Keep the memory_graph tool around to visualize tricky Python situations, also with boot.dev exercises.

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u/ghost59 9d ago

Honestly. This was fun. I am almost done with go on boot.dev. I'll star the repo. Time to become cracked.