numpy-discussion

[Numpy-discussion] How to share memory when bArr is smaller-sized than aArr

[Sebastian H. <ha...@ms...>]

Hi,
in numarray I could do this
>>> import numarray as na
>>> a = na.arange(10)
>>> b = na.array(a._data, type=na.int32, shape=8)

b would use the beginning part of a.

This is actually important for inplace FFT (where in real-to-complex-fft the 
input has 2 "columns" more memory than the output)

I found that in numpy there is no shape argument in array() at all anymore !

How can this be done with numpy ?

Thanks,
Sebastian Haase

Re: [Numpy-discussion] How to share memory when bArr is smaller-sized than aArr

[Travis O. <oli...@ie...>]

Sebastian Haase wrote:
> Hi,
> in numarray I could do this
>   
>>>> import numarray as na
>>>> a = na.arange(10)
>>>> b = na.array(a._data, type=na.int32, shape=8)
>>>>         
>
> b would use the beginning part of a.
>
> This is actually important for inplace FFT (where in real-to-complex-fft the 
> input has 2 "columns" more memory than the output)
>
> I found that in numpy there is no shape argument in array() at all anymore !
>
>   
No, there is no shape argument anymore.  But, the ndarray() constructor 
does have the shape argument and can be used in this way.

so

import numpy as na
b = na.ndarray(buffer=a, dtype=na.int32, shape=9)

should work.

-Travis