I like this.
while ideally, eval(repr(an_object)) == object, in practice this is
already violated fro large arays -- so other than doctests, this shouldn't
cause too many headaches.
-CHB
On Mon, Sep 30, 2024 at 10:13 AM Marten van Kerkwijk
wrote:
> Hi All,
>
> When the repr of an array is shown, currently the dtype and shape are
> explicitly listed if these cannot be directly inferred from the list
> that is shown, i.e., if the dtype is not float64 or int64, and if the
> size of the array is zero, but the shape not the simple (0,).
>
> For instance,
>
> ```
> np.empty((10,2,0), dtype="i2")
> array([], shape=(10, 2, 0), dtype=int16)
> ```
>
> I propose to also show the shape for the (rare) case that an array is
> summarized, i.e., when it has more than the default threshold of 1000
> elements, and elements are replaced by `...`. The logic is that also in
> that case it is no longer clear what the shape actually is, which is
> useful information (e.g., if working in a notebook -- which is the
> original use case at https://github.com/numpy/numpy/issues/27461).
>
> I have a PR for that at https://github.com/numpy/numpy/pull/27482
> which would lead to the following:
>
> ```
> np.arange(1001)
> array([ 0,1,2, ..., 998, 999, 1000], shape=(1001,))
> ```
>
> Just to be sure: this PR causes *no* change for any arrays with sizes
> less than a 1000, so I do not believe this change will lead to a lot of
> unnecessary churn for down-stream packages. Indeed, between numpy and
> astropy (which has lots of doctests), the only changes to (doc)tests
> that were needed are the very few for arrays where the "threshold" is
> explicitly exceeded.
>
> One irritant is that the shape is not an argument that can be passed in
> to an `np.array` call. While this is just as much the case for
> zero-sized arrays, perhaps a better solution would be to move the shape
> information out of the parentheses, e.g., using ``...) # shape=(...)``.
> I can change the PR to do that if that's the consensus.
>
> All the best,
>
> Marten
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