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TYP: fix random.Generator.choice output type for int sequences - #31877

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jorenham:typing/random.Generator.choice-sctype
Jul 6, 2026
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TYP: fix random.Generator.choice output type for int sequences#31877
charris merged 1 commit into
numpy:mainfrom
jorenham:typing/random.Generator.choice-sctype

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@jorenham

@jorenham jorenham commented Jul 6, 2026 •
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Both these cases were typed as int in the stubs:

In [1]: rng.choice(3)
Out[1]: 0

In [2]: rng.choice([1,2,3])
Out[2]: np.int64(1)

The second (rng.choice([1,2,3])) case was wrong, and is now correctly annotated to return np.int_ in the stubs as well.

This matters because int and np.int_ are incompatible types.

Fully written by me (a human, I think); bug found by Claude Fable 5 (high) (here's the full audit for those interested).

@rkern

rkern commented Jul 6, 2026

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If you just omit that overload, does it not get caught by the _ArrayLike[ScalarT] that follows? Or am I expecting too much out of _ArrayLike[ScalarT]?

@jorenham

jorenham commented Jul 6, 2026 •
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If you just omit that overload, does it not get caught by the _ArrayLike[ScalarT] that follows? Or am I expecting too much out of _ArrayLike[ScalarT]?

_ArrayLike[ScalarT] only matches array-likes with a known numpy scalar type (ScalarT: np.generic), so it indeed won't match a sequence of builtin python ints.

@charris
charris merged commit d376aa2 into numpy:main Jul 6, 2026
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@charris

charris commented Jul 6, 2026

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Thanks Joren.

@jorenham
jorenham deleted the typing/random.Generator.choice-sctype branch July 6, 2026 17:07
@charris charris removed the 09 - Backport-Candidate PRs tagged should be backported label Jul 6, 2026
@charris charris mentioned this pull request Jul 6, 2026
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charris pushed a commit that referenced this pull request Jul 6, 2026
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TYP: fix random.Generator.choice output type for int sequences (#…
89cc181 
…31877)
MaanasArora pushed a commit to MaanasArora/numpy that referenced this pull request Jul 7, 2026
@jorenham @MaanasArora
TYP: fix random.Generator.choice output type for int sequences (n…
aea55d1 
…umpy#31877)
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41 - Static typing component: numpy.random

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@jorenham @rkern @charris