On 01/25/2018 08:53 PM, Chris Barker - NOAA Federal wrote:
>> On Jan 25, 2018, at 4:06 PM, Allan Haldane <allanhald...@gmail.com> wrote:
>
>>> 1) This is a known change with good reason?
>
>> . The
>> change occurred because the old assignment behavior was dangerous, and
>> was not doing what you thought.
>
> OK, that’s a good reason!
>
>>> A) improve the error message.
>>
>> Good idea. I'll see if we can do it for 1.14.1.
>
> What do folks think about a totuple() method — even before this I’ve
> wanted that. But in this case, it seems particularly useful.
>
> -CHB
Two thoughts:
1. `totuple` makes most sense for 2d arrays. But what should it do for
1d or 3+d arrays? I suppose it could make the last dimension a tuple, so
1d arrays would give a list of tuples of size 1.
2. structured array's .tolist() already returns a list of tuples. If we
have a 2d structured array, would it add one more layer of tuples? That
would raise an exception if read back in by `np.array` with the same dtype.
These points make me think that instead of a `.totuple` method, this
might be more suitable as a new function in np.lib.recfunctions. If the
goal is to help manipulate structured arrays, that submodule is
appropriate since it already has other functions do manipulate fields in
similar ways. What about calling it `pack_last_axis`?
def pack_last_axis(arr, names=None):
if arr.names:
return arr
names = names or ['f{}'.format(i) for i in range(arr.shape[-1])]
return arr.view([(n, arr.dtype) for n in names]).squeeze(-1)
Then you could do:
>>> pack_last_axis(uv).tolist()
to get a list of tuples.
Allan
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