[파이썬][numpy] numpy `cumprod`와 `cumsum`

Numpy is a powerful library in Python for numerical computing. It provides a wide range of functions to perform various operations on arrays, including cumulative product and cumulative sum. In this blog post, we will explore the cumprod and cumsum functions in numpy and understand how to use them in Python.

The cumprod Function

The cumprod function in numpy calculates the cumulative product of elements along a specified axis of an array. It returns an array of the same shape as the input array, where each element is the product of all previous elements along the specified axis.

Here’s an example to illustrate how cumprod works:

import numpy as np

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

cumulative_product = np.cumprod(arr)

print(cumulative_product)

Output:

[  2   6  24 120]

In the above example, the cumprod function calculates the cumulative product of the elements in the array [2, 3, 4, 5]. The resulting array [2, 6, 24, 120] is obtained by multiplying each element with the previous cumulative product.

The cumsum Function

Similarly, the cumsum function in numpy calculates the cumulative sum of elements along a specified axis of an array. It returns an array of the same shape as the input array, where each element is the sum of all previous elements along the specified axis.

Let’s see an example to understand how cumsum works:

import numpy as np

arr = np.array([2, 4, 6, 8])

cumulative_sum = np.cumsum(arr)

print(cumulative_sum)

Output:

[ 2  6 12 20]

In the above example, the cumsum function calculates the cumulative sum of the elements in the array [2, 4, 6, 8]. The resulting array [2, 6, 12, 20] is obtained by adding each element with the previous cumulative sum.

Conclusion

The cumprod and cumsum functions in numpy are useful for calculating cumulative product and cumulative sum, respectively. They provide a convenient way to perform these operations on arrays with just a single function call. By utilizing these functions, you can efficiently analyze and manipulate data in Python.

In this blog post, we covered the basics of cumprod and cumsum functions in numpy. Experiment with different arrays and axis parameters to explore their functionalities further. Numpy offers a wide range of mathematical and statistical functions that can greatly simplify your data analysis tasks.