`numpy:select`

source: /dev/numpy/build-install/usr/lib/python3.14/site-packages/numpy/lib/_function_base_impl.py:812

Signature

def select(condlist, choicelist, default = 0)

Summary

Return an array drawn from elements in choicelist, depending on conditions.

Parameters

condlist : list of bool ndarrays: The list of conditions which determine from which array in choicelist the output elements are taken. When multiple conditions are satisfied, the first one encountered in condlist is used.
choicelist : list of ndarrays: The list of arrays from which the output elements are taken. It has to be of the same length as condlist.
default : scalar, optional: The element inserted in output when all conditions evaluate to False.

Returns

output : ndarray: The output at position m is the m-th element of the array in choicelist where the m-th element of the corresponding array in condlist is True.

Examples

import numpy as np

✓

Beginning with an array of integers from 0 to 5 (inclusive), elements less than ``3`` are negated, elements greater than ``3`` are squared, and elements not meeting either of these conditions (exactly ``3``) are replaced with a `default` value of ``42``.

x = np.arange(6)
condlist = [x<3, x>3]
choicelist = [-x, x**2]

✓

np.select(condlist, choicelist, 42)

✗

array([ 0, -1, -2, 42, 16, 25])

When multiple conditions are satisfied, the first one encountered in `condlist` is used.

condlist = [x<=4, x>3]
choicelist = [x, x**2]
np.select(condlist, choicelist, 55)

✓

array([ 0,  1,  2,  3,  4, 25])

Aliases

numpy.select