On 4/22/07, Travis Oliphant <oliphant.travis@ieee.org> wrote:
Bill Baxter wrote:
What's the right way to make a new numpy array that's a copy of some C data?
What do you mean by /copies/ the void * data pointer for you? Do you mean the API would
1) Create new memory for the array 2) Copy the data from another void * pointer to the memory just created for the new array?
Yes.
If that is what you mean, then you are right there is no such API. I'm not sure that there needs to be one. It is a two-liner using memcpy.
Ok, I see. That's not too hard. Though as Sebastian said below it would be a little trickier if I needed to do a transpose or something at the same time. I guess for those cases it should be possible to make a temporary PyArrayObject with PyArray_NewFromDescr that wraps the memory and then do a PyArray_GETCONTIGUOUS?
A related question -- I'm only trying to copy in order to save myself a little hassle regarding how to clean up the allocated chunks. If there's some simple way to trigger a particular deallocation function to be called at the right time, then that would be the ideal, really.
No, there is no place to store that information in NumPy. Either the ndarray dealloc function frees the memory it created or it doesn't free any memory. I think the best thing to do in this case would be to create a memory object wrapping the pointer and then point the ndarray to it as the source of memory.
Hmm. Sounds a little over my head. I'll stick with copying for now. --bb