Array indexing

Elements from NumPy arrays can be selected using four methods: scalar selection, slicing, numerical indexing, and logical (or Boolean) indexing. Scalar selection and slicing are the basic methods to access elements in an array, which has already been discussed here. Numerical indexing and logical indexing are closely related and allows more flexible selection. Numerical indexing uses lists or arrays of locations to select elements, whereas logical indexing uses arrays that contain Boolean values to select elements.

Numerical indexing

Numerical indexing is an alternative to slice notation. The idea in numerical indexing is to use coordinates to select elements. This is similar to slicing. Arrays created using numerical indexing create copies of data, whereas slices are only views of data, and not copies. For performance sake, slicing should be used. Slices are similar to one-dimensional arrays, but the shape of the slice is determined by the slice inputs.

Numerical indexing in...