[Numpy-discussion] moving window product
Mon Mar 21 12:19:09 CDT 2011
On Mon, Mar 21, 2011 at 10:10 AM, Brent Pedersen <firstname.lastname@example.org> wrote:
> hi, is there a way to take the product along a 1-d array in a moving
> window? -- similar to convolve, with product in place of sum?
> currently, i'm column_stacking the array with offsets of itself into
> window_size columns and then taking the product at axis 1.
> w = np.column_stack(a[i:-window_size+i] for i in range(0, window_size))
> window_product = np.product(w, axis=1)
> but then there are the edge effects/array size issues--like those
> handled in np.convolve.
> it there something in numpy/scipy that addresses this. or that does
> the column_stacking with an offset?
The Bottleneck package has a fast moving window sum (bn.move_sum and
bn.move_nansum). You could use that along with
>> a = np.random.rand(5)
Or you could use strides or scipy.ndimage as in
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