How to select the subarray of a NumPy array satisfying a condition

The following code shows to get the subarray of an array satisfying the condition.

import numpy

a = numpy.array([3, 5, 7, 9, 11])

b = a[a > 6]

print(b)  # [ 7  9 11]

The sentence in brackets is the condition. You can select the even integers as array.

import numpy

a = numpy.array([1, 2, 3, 4])

b = a[a % 2 == 0]

print(b)  # [2 4]

Matrix and condition

Here's an example of selecting items from matrix.

import numpy

a = numpy.array([[1, 2, 3], [4, 5, 6]])

b = a[a > 2]

print(b)  # [3 4 5 6]