`numpy:compress`

source: /dev/numpy/build-install/usr/lib/python3.14/site-packages/numpy/_core/fromnumeric.py :2137

Signature

def compress ( condition , a , axis = None , out = None )

Summary

Return selected slices of an array along given axis.

Extended Summary

When working along a given axis, a slice along that axis is returned in output for each index where condition evaluates to True. When working on a 1-D array, compress is equivalent to extract.

Parameters

condition : 1-D array of bools: Array that selects which entries to return. If len(condition) is less than the size of a along the given axis, then output is truncated to the length of the condition array.
a : array_like: Array from which to extract a part.
axis : int, optional: Axis along which to take slices. If None (default), work on the flattened array.
out : ndarray, optional: Output array. Its type is preserved and it must be of the right shape to hold the output.

Returns

compressed_array : ndarray: A copy of a without the slices along axis for which condition is false.

Examples

import numpy as np
a = np.array([[1, 2], [3, 4], [5, 6]])
a
np.compress([0, 1], a, axis=0)
np.compress([False, True, True], a, axis=0)
np.compress([False, True], a, axis=1)

✓

Working on the flattened array does not return slices along an axis but selects elements.

np.compress([False, True], a)

✓

Aliases

numpy.compress