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@ee.byu.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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