# Access Elements of Array – Numpy

Contents

## NumPy – Access elements of array

To access elements of a numpy array, you can use indexing operator [].

The indexing operator takes an integer or a list of integers representing the indices of elements you want to access.

index starts with a value of 0 for first element, and increments by one for subsequent elements.

If arr is numpy array, then the following expression accesses the element at index=5.

``arr``

If arr is numpy array, then the following expression accesses the elements from start index of 5 to a stop index of 10 (stop not included in the returned object).

``arr[5:10]``

We can also specify a step value, with the following syntax.

``arr[start:stop:step]``

If the array is multi-dimensional then we can specify the indices for as many dimensions as required.

``arr[index_1][index_2]``

Accessing a range of elements is called slicing, and please refer the tutorial – NumPy Array Slicing.

## Examples

### 1. Access element at index=5

In the following program, we take a numpy array (one dimensional), and access the element at index=5.

Python Program

``````import numpy as np

arr = np.array([1, 2, 4, 9, 16, 25, 36, 49, 64])
element = arr
print(element)``````
Run Code Copy

Output

``25``

Explanation

``````[1, 2, 4, 9, 16, 25, 36, 49, 64] <- arr
0  1  2  3   4   5   6   7   8  <- indices
arr is 25``````

### 2. Access elements from index=2 until index=6

In the following program, we take a numpy array (one dimensional), and access the elements from index=2 until index=6.

Python Program

``````import numpy as np

arr = np.array([1, 2, 4, 9, 16, 25, 36, 49, 64])
elements = arr[2:6]
print(elements)``````
Run Code Copy

Output

``[ 4  9 16 25]``

Explanation

``````[1, 2, 4, 9, 16, 25, 36, 49, 64] <- arr
0  1  2  3   4   5   6   7   8  <- indices
|--------------|
4, 9, 16, 25 <-  arr[2:6]   ``````

### 3. Access elements from index=2 until index=8 in steps of 2

In the following program, we take a numpy array (one dimensional), and access the elements from index=2 until index=8 in steps of 2.

Python Program

``````import numpy as np

arr = np.array([1, 2, 4, 9, 16, 25, 36, 49, 64])
elements = arr[2:8:2]
print(elements)``````
Run Code Copy

Output

``[ 4 16 36]``

Explanation

``````[1, 2, 4, 9, 16, 25, 36, 49, 64] <- arr
0  1  2  3   4   5   6   7   8  <- indices
|-      -       -     |
4,    16,     36       <-  arr[2:8:2]   ``````

## Summary

In this NumPy Tutorial, we learned how to access elements of a numpy array using indexing operator.

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