[Numpy-discussion] two questions about `choose`

Alan G. Isaac alan.isaac at gmail.com
Sun Apr 18 08:39:36 EDT 2021


I think you are saying that this current behavior of `choose` should
be considered a bug. I hope not, because as illustrated, it is useful.
How would you propose to efficiently do the same substitutions?


On 4/17/2021 4:27 PM, Kevin Sheppard wrote:
> 2. I would describe this a a bug. I think sequences are converted to arrays and in this case the conversion is not returning a 2 element object array but 
> expanding and then concatenation.

> On Sat, Apr 17, 2021, 18:56 Alan G. Isaac <alan.isaac at gmail.com <mailto:alan.isaac at gmail.com>> wrote:

>     2. Separately, mypy is unhappy with my 2nd argument to `choose`:
>     Argument 2 to "choose" has incompatible type "Tuple[int, Sequence[float]]";
>     expected "Union[Union[int, float, complex, str, bytes, generic], Sequence[Union[int, float, complex, str, bytes, generic]],
>     Sequence[Sequence[Any]],_SupportsArray]"
>     However, `choose` is happy to have e.g. `choices=(0,seq)` (and I hope it will remain so!).
> 
>     E.g.,
>     a = a = (0,1,1,0,0,0,1,1)  #binary array
>     np.choose(a, (0,range(8))     #array([0, 1, 2, 0, 0, 0, 6, 7])


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