np.expand_dims

The numpy function np.expand_dims() is used to add an extra dimension to an existing numpy array.

Syntax:

np.expand_dims(arr, axis)

Parameters:
- arr: the numpy array to be expanded
- axis: the axis along which the new dimension will be added. If axis is not specified, a new dimension will be added at the beginning of the array.

Returns:
- A new numpy array with the same data as the original array, but with an additional dimension inserted.

Example:

import numpy as np

arr = np.array([1, 2, 3])
print(arr.shape)  # Output: (3,)

# Add a new dimension to the array
new_arr = np.expand_dims(arr, axis=0)
print(new_arr.shape)  # Output: (1, 3)

# Add a new dimension to the array at the end
new_arr2 = np.expand_dims(arr, axis=1)
print(new_arr2.shape)  # Output: (3, 1)

In this example, we first define a numpy array `arr` with shape (3,). We then use np.expand_dims() to add a new dimension to the array at axis=0 and axis=1. The resulting arrays are `new_arr` with shape (1, 3) and `new_arr2` with shape (3, 1).