boolean_indexing.py

import numpy as np
a1=np.array([[0,1,2,3],[4,5,6,7],[8,9,10,11],[12,13,14,15]])
print (a1)
#Output:
[[ 0  1  2  3]
 [ 4  5  6  7]
 [ 8  9 10 11]
 [12 13 14 15]]

#Accessing elements which are greater than 5
print (a1[a1>5])
#Output:[ 6  7  8  9 10 11 12 13 14 15]

#Accessing elements which are greater than 5 and less than 10
print (a1[(a1>5)&(a1<10)])
#Output:[6 7 8 9]

#Modifying elements which are greater than 11 by adding 100 to it.
a1[a1>11]+=100
print (a1)
#Output:
[[  0   1   2   3]
 [  4   5   6   7]
 [  8   9  10  11]
 [112 113 114 115]]