Change coordinates with a purpose

THE IDEA

Read the example.

A linear transformation can rotate, scale, shear or project data. Rotation changes coordinates while preserving Euclidean lengths and angles. A projection can discard information by mapping several original points to the same location.

y = Ax

Use it well

Adding an offset gives an affine transformation, Ax + b, rather than a purely linear one. Preprocessing choices belong inside the training and evaluation process.