A. M. Archibald wrote:
> On 01/11/06, Bill Baxter <[EMAIL PROTECTED]> wrote:
>
>
>> What's the reason iterators are not supported currently?
>> For instance A[range(0,4)] works for a 1d A, but A[xrange(0,4)] does not.
>> Are iterators just too inefficient to bother with?
>>
>
> If you want an iterator back, a generator comprehension will do it:
> (A[i] for i in xrange(0,4))
>
> If the result is to be a numpy array, the size must be known ahead of
> time (so that the memory can be allocated) and specified. At this
> point, and considering the overhead in calling back and forth to the
> generator, the cost of converting to a list (after all,
> A[list(xrange(0,40)] should work fine) isn't necessarily worth the
> trouble.
>
Another option for converting an iterator to a sequence that might be
helpful, particularly if result is large, is to use fromiter. For example:
a[numpy.fromiter(xrange(0,40, 2), int)]
-tim
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