Thanks Travis,

I guess we'll have to tweak the fortran subroutines. It would have been neat
though.

David

Answer: Since g+=1 adds one to all N elements of g, the buffer a gets
incremented N times.
So
a = array(i)
g = ndarray(shape=(1,N), dtype=int, buffer=a, strides=(0,0))
g+=M

returns i + M*N



2006/12/6, Travis Oliphant <oliphant@[...].edu> :
> 
>  David Huard wrote:
> 
>  > Hi,
>  >
>  > I have fortran subroutines wrapped with f2py that take arrays as
>  > arguments, and I often need to use resize(a, N) to pass an array of
>  > copies of an element. The resize call , however, is becoming the speed
>  > bottleneck, so my question is:
>  > Is it possible to create an (1xN) array from a scalar without
>  > allocating additional memory for the array, ie just return a new
>  > "view" of the array where all elements point to the same scalar.
>  >
>  I don't think this would be possible in Fortran because Fortran does not
>  provide a facility for using arbitrary striding (maybe later versions of
>  Fortran using pointers does, though).
> 
>  If you can use arbitrary striding in your code, then you can construct
>  such a view using appropriate strides (i.e.  a stride of 0).  You can do
>  this with the ndarray constructor:
> 
> 
>  a = array(5)
>  g = ndarray(shape=(1,10), dtype=int, buffer=a, strides=(0,0))
> 
>  But, notice you will get interesting results using
> 
>  g += 1
> 
>  Explain why the result of this is an array of 15 (Hint:  look at the
>  value of a).
> 
>  -Travis
> 
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