[SciPy-user] numpy array in ctype struct

Rob Hetland hetland@tamu....
Thu Jan 24 01:39:24 CST 2008

On Jan 23, 2008, at 3:44 PM, Ryan May wrote:

> I may be grokking this incorrectly, but I think your problem lies  
> here.
>  I'm not sure what you're trying to accomplish with this loop (since
> setting to NULL isn't necessary before free-ing).  What it actually  
> does
> is set the value at the memory address located at pts[i] to NULL (0).
> This will end up modifying the values in pts1 itself. (Since pts[i] =
> pts1 + i*dim, then *pts[i] is the same as pts1[i*dim].)

This part wasn't intended to be the 'real' code, rather I just was  
trying different things out.  I guess I didn't explain this well  
enough in my last message.  Resetting the pointers like this does not  
seem to change the numpy array passed to the *double pointer, whereas  
freeing the new **double does erase those values.

>>      free(pts);   /// this seems to also delete the input data (pts1)
>> in python..
> I'm not sure this is really the case.  It looks like a perfect  
> match for
> the malloc above.

Yes, that's what I thought, but it doesn't seem to work like I  
thought it would.

> If that loop isn't causing the problem, then the problem likely lies
> elsewhere.

Yes, after your comments, it seems that is the only thing left..  I  
was just checking to see if someone had run across this before.  I  
had tested for other possible problems, but I guess I will have to  
keep looking.


Rob Hetland, Associate Professor
Dept. of Oceanography, Texas A&M University
phone: 979-458-0096, fax: 979-845-6331

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