The numpy.where() function returns the indices of elements in an input array where the given condition is satisfied.
Syntax :numpy.where(condition[, x, y])
Parameters:
condition : When True, yield x, otherwise yield y.
x, y : Values from which to choose. x, y and condition need to be broadcastable to some shape.Returns:
out : [ndarray or tuple of ndarrays] If both x and y are specified, the output array contains elements of x where condition is True, and elements from y elsewhere.If only condition is given, return the tuple condition.nonzero(), the indices where condition is True.
Code #1:
# Python program explaining # where() function import numpy as np np.where([[True, False], [True, True]], [[1, 2], [3, 4]], [[5, 6], [7, 8]]) |
Output :
array([[1, 6],
[3, 4]])
Code #2:
# Python program explaining # where() function import numpy as np # a is an array of integers.a = np.array([[1, 2, 3], [4, 5, 6]]) print(a) print ('Indices of elements <4') b = np.where(a<4)print(b) print("Elements which are <4")print(a[b]) |
Output :
[[1 2 3] [4 5 6]] Indices of elements <4 (array([0, 0, 0], dtype=int64), array([0, 1, 2], dtype=int64)) Elements which are <4 array([1, 2, 3])
