On Jun 6, 2009, at 2:20 AM, Dag Sverre Seljebotn wrote:
> Eric Firing wrote:
>> Eric Firing wrote:
>>> In writing a cython extension to work with numpy masked arrays, I
>>> needed to work with the mask, which is dtype('bool'). Therefore I
>>> was expecting to be able to use np.bool_t, in analogy to np.float_t.
>>> Instead I had to use np.int8_t, and cast the input to np.int8 in a
>>> python wrapper. Can bool_t be added to numpy.pxd?
>>>
>>> Thanks.
>>>
>>> Eric
> The reason it is not there is that AFAIK Cython has no support for an
> 8-bit boolean type. I.e. you want
>
> print arr[3] # should print "True", not 1.
>
> and furthermore you want
>
> arr[3] = obj # should mean arr[3] = bool(obj)
>
> Which brings up the questions
> 1) I suppose the best thing would be to add support for a "bool" which
> would be a C99 _Bool if compiling on C99, and "unsigned char" with
> appropriate restrictions otherwise. Thoughts?
How would this relate to the current bint type? bint is an int
because logical operations in C are ints, and also several operations
in the Python/C API (and elsewhere) return true/false values as ints.
> 2) Is it better to keep ndarray[bool_t] disabled until this
> happens, or
> should it be enabled (as an "unsigned char" array) and then change its
> semantics later?
I would be OK with allowing bool_t to be a synonym for int8_t, and
then widening the semantics later (I don't see what would break,
unless one was storing actual integer (rather than boolean) values).
- Robert
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