[Numpy-discussion] Method to shift elements in an array?

Mads Ipsen mpi at osc.kiku.dk
Wed Feb 22 11:41:18 CST 2006


On Wed, 22 Feb 2006, Alan G Isaac wrote:

> On Wed, 22 Feb 2006, Zachary Pincus apparently wrote:
> > Does numpy have an built-in mechanism to shift elements along some
> > axis in an array? (e.g. to "roll" [0,1,2,3] by some offset, here 2,
> > to make [2,3,0,1])
>
> This sounds like the rotater command in GAUSS.
> As far as I know there is no equivalent in numpy.
> Please post your ultimate solution.
>
> Cheers,
> Alan Isaac
>

Similar to cshift() (cyclic shift) in F90. Very nice for calculating
finite differences, such as

  x' = ( cshift(x,+1) - cshift(x-1) ) / dx

This would be a very handy feature indeed.

// Mads




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