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my_dict = { 1: 11, 2: 12, 3: 13 }

If I want to work on the list of keys from my_dict there appear to be (at least) three ways to do this in Python >3.5 (i.e. on or after PEP 448)

List Comprehension:

[key for key in my_dict]

[1, 2, 3]

Unpacking:

[*my_dict]

[1, 2, 3]

Constructing a list from the view of the keys:

list(my_dict.keys())

[1, 2, 3]

Are these three methods interchangeable?

I think

  • [key for key in my_dict] is the most 'Pythonic',
  • [*my_dict] is the most terse, and
  • list(my_dict.keys()) is the most readable.

Are there any technical reasons for choosing between these?

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1 Answer 1

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2

These all accomplish the same thing. For the last one, calling keys() is not required. list(my_dict) will do the same thing. It's a little more clear if you call keys() explicitly so you might want to do it anyway.

The rest of this question is opinion-based. While all are valid options, I think 1 & 3 are preferable for this use and #2 makes sense for unpacking into method calls.

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