## How to elect elements or indices by conditions from Numpy Array in Python ?

In this article we will see how we can select and print elements from a given Numpy array provided with multiple conditions.

### Selecting elements from a Numpy array based on Single or Multiple Conditions :

When we apply a comparison operator to a numpy array it is applied to each & every elements of the array. It is seen that True or False will be returned as bool array accordingly when its elements satisfies the condition.

#Program : import numpy as sc # To create a numpy array from 2 to 25 with interval 23 num_arr = sc.arange(2, 25, 3) # To compare with all elements in array bool_arr = num_arr < 15 print(bool_arr)

Output : [ True True True True True False False False]

If we pass the resulted bool Numpy array in `[] operartor`

then it will form a new Numpy Array with elements which were found True in corresponding bool Numpy array.

#Program : import numpy as sc num_arr = sc.arange(2, 25, 3) bool_arr = num_arr < 15 print(bool_arr) # Those elements will be selected where it is True at corresponding value in bool array new_arr = num_arr[bool_arr] print(new_arr)

Output : [ True True True True True False False False] [ 2 5 8 11 14]

### Select elements from Numpy Array which are divisible by 5 :

We can select and print those elements which are divisible by 5 from given Numpy array.

#Program : import numpy as sc # Numpy arrray with elements frrm 3 to 25 num_arr = sc.arange(3, 25, 1) # To select those numbers which are divisible by 5 new_arr = num_arr[num_arr%5==0] print(new_arr)

Output : [ 5 10 15 20 ]

### Select elements from Numpy Array which are greater than 10 and less than 18 :

We can select and print those elements which are smaller than 10 and greater than 18 from given Numpy array.

#Program : import numpy as sc # Numpy arrray with elements frrm 3 to 25 num_arr = sc.arange(3, 25, 1) # To select those numbers which are greater than 10 and smaller than 18 new_arr = num_arr[(num_arr > 10) & (num_arr < 18)] print(new_arr)

Output : [11 12 13 14 15 16 17]