cc @ngoldbaum @seberg @ikrommyd

Could you do a scan if there are any other functions where partial modification can occur on the out array?

Could you do a scan if there are any other functions where partial modification can occur on the out array?

caller's array can be left partially modified on error in these

• sort / partition (in-place, raising object comparison)
• a[mask] = vals and a[idx] = vals / put_along_axis (failing value cast mid-write)
• np.copyto / dst[...] = src / concatenate(out=) when the casting rule allows an element-wise-failing cast
• np.round(out=, decimals != 0) (leaves intermediate a * 10**decimals values) and np.mean(out=) (leaves undivided sum)
• ufuncs with a matching-dtype out (elementwise, reduce, accumulate, reduceat, object matmul/dot, einsum) the loop writes straight into out
• argmax / argmin with out on object dtype

fyi: take/choose weren't fully shielded by their internal copy either so i added to the pr

@seberg do you think one should add the note to all cases where an exception being raised can cause partial modification to out array here in this PR?

This has ballooned into way to much reviewer work for something that is really not a problem. Please don't continue adding on more followup PRs for this.

This has ballooned into way to much reviewer work for something that is really not a problem. Please don't continue adding on more followup PRs for this.

the scan was a response to @ikrommyd 's question. The other issues are independent of this specific fix :)

I will avoid adding more follow ups from now on. thanks for flagging this!

I was probably not clear enough. I only wanted to identify if there are any other places to put the add_note helper where the user is already visibly experiencing a partial modification in the out array and we can just improve the error they are already getting.