On Oct 7, 2009, at 10:28 AM, Michael Droettboom wrote:
> I'm noticing an inconsistency as to how complex numbers are
> byteswapped
> as arrays vs. scalars, and wondering if I'm doing something wrong.
>
>>>> x = np.array([-1j], '<c8')
>>>> x.tostring().encode('hex')
> '00000000000080bf'
> # This is a little-endian representation, in the order (real, imag)
>
> # When I swap the whole array, it swaps each of the (real, imag) parts
> separately
>>>> y = x.byteswap()
>>>> y.tostring().encode('hex')
> '00000000bf800000'
> # and this round-trips fine
>>>> z = np.fromstring(y.tostring(), dtype='>c8')
>>>> assert z[0] == -1j
>>>>
>
> # When I swap the scalar, it seems to swap the entire 8 bytes
>>>> y = x[0].byteswap()
>>>> y.tostring().encode('hex')
> 'bf80000000000000'
> # ...and this doesn't round-trip
>>>> z = np.fromstring(y.tostring(), dtype='>c8')
>>>> assert z[0] == -1j
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> AssertionError
>>>>
>
> Any thoughts?
I just checked a fix for this into SVN (tests still need to be added
though...)
I can't currently build SVN on my Mac for some reason (I don't know if
it has to do with recent changes or not, but I don't have time to
track it down right now....the error I'm getting is something about
Datetime array scalar types not being defined which seems related to
the work Dave and Stefan have been discussing).
It's a small change, though, and should work.
-Travis
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