Re: [Numpy-discussion] Accessing a Numeric 'c' array from numarray]

[Francesc A. <fa...@op...>]

A Dissabte 18 Gener 2003 17:41, Todd Miller va escriure:
> >I just want to access the buffer data, and the shape of this object fr=
om C
> >(well, I'm actually using Pyrex, but I think this is not important). I=
s
> > that possible by only using numarray C calls?
>
> Look at Lib/chararray.py and Src/_chararraymodule.c.
>
> If you can handle using a CharArray or RawCharArray, try:
>
> 1. call NA_updateDataPtr( array ) to refresh the data buffer pointer in
> the PyArrayObject.  Even _chararraymodule.c doesn't do this right yet.
>
> 2. call NA_OFFSETDATA(array) to add the byteoffset to the pointer.
>
> 3. shape, strides, and itemsize should be directly accessible from the
> PyArrayObject.

Ok. I'll try to do that.

>
> CharArray has some extra stripping and padding semantics; these are laz=
y
> and hence absent without extra care in C.  RawCharArray has none.
>

By the way, is it safe to assume that CharArray objects are contiguous? o=
r
RawCharArray?. The same question goes for RecArray objects. Or it is alwa=
ys
convenient to check with iscontiguous() method if they are or not?. In ca=
se
these objects can be non-contiguous, I guess there's still not a function
like NA_InputArray that works with CharArray or RecArray objects in order=
 to
obtain well-behaved objects. Is that true?

I think it would be possible to me to include support for numarray object=
s
in next release of PyTables. Thanks!,

--=20
Francesc Alted