Can you explain axis=-1 with an example?

Sure! Let's look at a simple example using a 2D NumPy array to illustrate how axis=-1 works.

import numpy as np

# Create a 2D array (3 rows and 2 columns)
array = np.array([[1, 2],
                  [3, 4],
                  [5, 6]])

# Print the original array
print("Original Array:")
print(array)

# Sum along axis=-1 (which is the same as axis=1)
sum_axis_minus1 = np.sum(array, axis=-1)

# Print the result
print("\nSum along axis=-1:")
print(sum_axis_minus1)

Explanation:

Original Array:
```
[[1, 2],
 [3, 4],
 [5, 6]]
```
Sum along axis=-1:
- When we sum along axis=-1, we are summing across the columns for each row.
- For the first row: 1 + 2 = 3
- For the second row: 3 + 4 = 7
- For the third row: 5 + 6 = 11
Result:
```
[ 3,  7, 11]
```

So, the output of sum_axis_minus1 will be [3, 7, 11], which represents the sum of each row in the original array.