What is the numpy sum function and how do I use it?

What is the numpy sum function and how do I use it?

The numpy sum function is used to calculate the sum of array elements over a specified axis. You can use it like this: numpy.sum(array, axis=None).

Can you give me an example of how to use it with a 2D array?

Sure! Here's an example:

import numpy as np
array = np.array([[1, 2, 3], [4, 5, 6]])
sum_total = np.sum(array)
print(sum_total)  # Output: 21

This sums all elements in the 2D array.

What if I want to sum along a specific axis?

You can specify the axis parameter. For example, np.sum(array, axis=0) sums along the columns, while np.sum(array, axis=1) sums along the rows.

Can I sum only certain elements based on a condition?

Yes! You can use boolean indexing to filter elements before summing. For example:

sum_filtered = np.sum(array[array > 3])
print(sum_filtered)  # Output: 21