Split a List Into Evenly Sized Chunks in Python Using NumPy

In the world of Python programming, there often arises a need to divide a list into smaller, equally sized chunks. In this example, you will learn how to split a list into evenly sized chunks in Python using NumPy. We will dive into the step-by-step process of utilizing the np.array_split() function, which allows us to divide a list or array into specified subarrays. We will also discuss the benefits and applications of using this approach, providing practical examples along the way.

In the world of programming, it is often necessary to manipulate and process data in various ways to achieve desired outcomes. One common task is to split a list into evenly sized chunks, which can be useful for tasks such as parallel processing, data analysis, or dividing workloads. In Python, there are multiple approaches to achieve this, and one efficient method is by utilizing the power of the NumPy library.

So, let’s delve into the world of NumPy and learn a Python program to split a list into evenly sized chunks using NumPy.

Python Program to Split a List Into Evenly Sized Chunks Using NumPy

# Split a List Into Evenly Sized Chunks in Python Using NumPy 

import numpy as np

arr = range(30)
np.array_split(arr, 6)

Code Explanation

Importing the NumPy library

First, we need to import the NumPy library to utilize its functions and capabilities. We will import it using the alias np.

Creating a List

Next, we create a list called arr that contains a sequence of numbers from 0 to 29 using the range() function. This list represents the data that we want to split into evenly sized chunks.

Splitting the List into Chunks

To split the list into evenly sized chunks, we use the np.array_split() function. This function takes two arguments: the array or list to be split (arr in our case) and the number of equally sized subarrays we want to create.

Obtain the Split Subarrays

The np.array_split() function divides the original list into the specified number of subarrays. In our example, we obtain six equally sized subarrays as a result. Each subarray contains a portion of the original data.

Printing the Split Subarrays

To observe the resulting subarrays, we can print them using the print() function. This will display the subarrays on the console, allowing us to verify the successful splitting of the list into evenly sized chunks.


[array([0, 1, 2, 3, 4]),
 array([5, 6, 7, 8, 9]),
 array([10, 11, 12, 13, 14]),
 array([15, 16, 17, 18, 19]),
 array([20, 21, 22, 23, 24]),
 array([25, 26, 27, 28, 29])]

This output represents the six equally sized subarrays obtained by splitting the original list [0, 1, 2, …, 28, 29] into chunks using the np.array_split() function from the NumPy library. Each subarray contains a portion of the original data, with each chunk having six elements.

Here are a few alternative methods to split a list into evenly sized chunks:

Using Yield:

This approach uses a generator function with the yield keyword to produce chunks one at a time. It is memory-efficient because it generates chunks on-the-fly without storing the entire result in memory. This method is useful when dealing with large lists or when memory usage is a concern.

Using for Loop:

With a for loop and slicing, we can iterate over the list and extract chunks of the desired size. This method is simple and intuitive to understand. It works well for small to medium-sized lists.

Using List Comprehension:

List comprehension offers a concise way to split a list into chunks using slicing notation. It creates a new list by iterating over the original list and extracting chunks of the desired size. This method is compact and readable, suitable for situations where code brevity is preferred.

Using itertools:

The islice function from the itertools module can be used to split a list into chunks. It offers various iteration tools for efficient and memory-friendly operations. This method is beneficial when working with iterators or when more advanced iteration functionalities are required.

Using Collections:

The deque class from the collections module can be utilized to split a list into chunks efficiently. Deque provides efficient operations for adding and removing elements from both ends. This method is useful when frequent appending or popping of elements is required during the splitting process.

Here, we used the NumPy method as it provides a straightforward and concise way to split a list into equally sized chunks. The function call clearly conveys the intention of dividing the data, making the code more readable and maintainable. When working with large datasets, NumPy’s underlying implementation can offer significant speed improvements compared to pure Python approaches like list comprehension or iteration. It has a large and active user community, which means you can find extensive documentation, tutorials, and support resources online. This makes it easier to learn and troubleshoot any potential issues


In this blog, we have explored the process of splitting a list into evenly sized chunks using the NumPy library in Python. By using the np.array_split() function, we were able to divide our list into the desired number of equally sized subarrays. This approach provides a simple and efficient way to partition data for various purposes, such as analysis, processing, or parallel computing. 

NumPy’s extensive capabilities for numerical computing make it a valuable tool in scientific and data-oriented applications. By understanding how to utilize NumPy’s functions effectively, you can enhance your ability to manipulate and work with data structures in Python. Splitting lists into evenly sized chunks is just one example of the many useful operations that can be accomplished using NumPy, and it opens up possibilities for handling data in a more structured and organised manner.

Frequently Asked Questions

How does the np.array_split() function work?

The np.array_split() function divides an array or list into equally sized subarrays. It takes two arguments: the array to be split and the number of desired subarrays. The function evenly distributes the elements of the array into the specified number of subarrays, maintaining the order of the elements.

Can I split a list into chunks of unequal sizes?

Yes, the np.array_split() function allows you to split a list into subarrays of unequal sizes. If the length of the list is not divisible by the desired number of subarrays, the function distributes the remaining elements in a balanced manner.

What happens if the list cannot be divided equally into the desired number of subarrays?

If the length of the list is not evenly divisible by the desired number of subarrays, the np.array_split() function will create subarrays of approximately equal size. The remainder of elements will be distributed across the subarrays, ensuring a balanced splitting as much as possible.

Are there any performance considerations when using np.array_split()?

The np.array_split() function is optimized for efficient splitting of arrays or lists. However, when dealing with extremely large datasets, it’s important to consider the available system resources and memory constraints to ensure optimal performance.

Can I split lists of different data types using np.array_split()?

Yes, np.array_split() can handle lists containing different data types. The function treats each element of the list as a separate entity and distributes them accordingly into the subarrays, regardless of their data type.

About The Author

Leave a Reply