scipy.signal.correlate(in1, in2, mode='full')[source]

Cross-correlate two N-dimensional arrays.

Cross-correlate in1 and in2, with the output size determined by the mode argument.

Parameters :

in1 : array_like

First input.

in2 : array_like

Second input. Should have the same number of dimensions as in1; if sizes of in1 and in2 are not equal then in1 has to be the larger array.

mode : str {‘full’, ‘valid’, ‘same’}, optional

A string indicating the size of the output:


The output is the full discrete linear cross-correlation of the inputs. (Default)


The output consists only of those elements that do not rely on the zero-padding.


The output is the same size as in1, centered with respect to the ‘full’ output.

Returns :

correlate : array

An N-dimensional array containing a subset of the discrete linear cross-correlation of in1 with in2.


The correlation z of two arrays x and y of rank d is defined as:

z[...,k,...] = sum[..., i_l, ...]
x[..., i_l,...] * conj(y[..., i_l + k,...])