[Numpy-discussion] wrapping question
jmiller at stsci.edu
Fri Oct 7 06:46:29 EDT 2005
usr01873 at prolocation.net wrote:
>I'm using the numarray package. I would like to use the numarray C API to
>create a new array object and fill it with data without copying. Also, I
The numarray C-API has a compatibility layer which supports most Numeric
C-API functionality. So, using numarray, you can write most
Numeric/Numeric3/scipy_core-like code in C. For historical reasons
numarray also has a wider set of native APIs (i.e. NA_vNewArray()), but
since numarray is likely to be replaced by scipy_core when it matures,
it's wisest to use the compatibility API.
>would like numarray to take care of freeing the data once the numarray
>object is destructed. I've managed to find some related posts in the
>mailing list archive, but it is really unclear which of these posts are
>still accurate and what the current 'recommended' approach is. See:
>Currently, I first create a new PyArrayObject that is large enough to hold
>array = NA_vNewArray(NULL,__numarray_type,tmp_num_dims,tmp_dims);
>then I pass array->data to a C function that reads the data from disk. Any
>comments on this approach?
That should work fine; 'array' owns the data and will free it when
'array' is destructed.
A better approach, however, is to use numarray's PyArray_FromDims()
which is the Numeric/Numeric3/scipy_core API.
>Also, I was wondering if numarray frees the
>data using this approach (because it also allocates the memory in the
>first place within the NA_vNewArray function.)
Yes, numarray will free the data allocated internally by
NA_vNewArray(). numarray will also free the data allocated by
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