How to find the Index of value in Numpy Array ?

In this article, we are going to find the index of the elements present in a Numpy array.

Using where() Method

where() method is used to specify the index of a particular element specified in the condition.

Syntax: numpy.where(condition[, x, y])

Example 1: Get index positions of a given value

Here, we find all the indexes of 3 and the index of the first occurrence of 3, we get an array as output and it shows all the indexes where 3 is present.

Output:

All index value of 3 is: [2 7]
First index value of 3 is: 2

Example 2: Print First Index Position of Several Values

Here, we are printing the index number of all values present in the values array.

Output:

index of first occurrence of each value: [1 2 9]

Example 3: Get the index of elements based on multiple conditions

Get the index of elements with a value less than 20 and greater than 12

Output:

Index of elements with value less than 20 and greater than 12 are: 
 (array([ 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15], dtype=int64),)

Get the index of elements in the Python loop

Create a NumPy array and iterate over the array to compare the element in the array with the given array. If the element matches print the index.

Output:

element index : 5

Using ndenumerate() function to find the Index of value

It is usually used to find the first occurrence of the element in the given numpy array.

Output:

(6,)

Using enumerate() function to find the Index of value

Here we are using the enumerate function and then checking the value with the target value.

Output:

6