Let us explore.

## Function Syntax

The function syntax is as shown below:

## Function Parameters

The function returns the parameters as shown:

- a – refers to the input array.
- axis – along which axis the cumulative sum is performed.
- dtype – specifies the data type of the output.
- out – specifies the output array to store the result.

## Function Return Value

The function returns a new array with the cumulative sum of the input array elements.

## Example #1

The code below shows how to calculate the cumulative sum of a two-dimensional array along the None axis.

import numpy as np

arr = np.array([[1,2,3], [4,5,6]])

print(f"result: {np.cumsum(arr, axis=None)}")

The code above should flatten the array and an array holding the cumulative sum of the elements.

An example output is as shown:

## Example #2

The following example shows how to use the cumsum() function along the zero axis.

print(f"result: {np.cumsum(arr, axis=0)}")

This should return:

[[1 2 3]

[5 7 9]]

## Example #3

Along the axis=1, the function returns the result as:

print(f"result: {np.cumsum(arr, axis=1)}")

The output array is as shown:

[[ 1 3 6]

[ 4 9 15]]

## Conclusion

Using this article, you learned how to calculate the cumulative sum of elements along a given axis in an input array using the cumsum() function. Feel free to explore the docs for more.

Thanks for reading!!