`scipy.signal._signaltools:order_filter`

source: build-install/usr/lib/python3.14/site-packages/scipy/signal/_signaltools.py:1547

Signature

def order_filter(a, domain, rank)

Summary

Perform an order filter on an N-D array.

Extended Summary

Perform an order filter on the array in. The domain argument acts as a mask centered over each pixel. The non-zero elements of domain are used to select elements surrounding each input pixel which are placed in a list. The list is sorted, and the output for that pixel is the element corresponding to rank in the sorted list.

Parameters

a : ndarray: The N-dimensional input array.
domain : array_like: A mask array with the same number of dimensions as a. Each dimension should have an odd number of elements.
rank : int: A non-negative integer which selects the element from the sorted list (0 corresponds to the smallest element, 1 is the next smallest element, etc.).

Returns

out : ndarray: The results of the order filter in an array with the same shape as a.

Examples

import numpy as np
from scipy import signal
x = np.arange(25).reshape(5, 5)
domain = np.identity(3)
x

✓

array([[ 0,  1,  2,  3,  4],
       [ 5,  6,  7,  8,  9],
       [10, 11, 12, 13, 14],
       [15, 16, 17, 18, 19],
       [20, 21, 22, 23, 24]])

signal.order_filter(x, domain, 0)
signal.order_filter(x, domain, 2)

✗

array([[ 6,  7,  8,  9,  4],
       [11, 12, 13, 14,  9],
       [16, 17, 18, 19, 14],
       [21, 22, 23, 24, 19],
       [20, 21, 22, 23, 24]])

Aliases

scipy.signal.order_filter