Introduction to NumPy and Matplotlib
Chapter 8: NumPy recap and exercises
Mean squared error
A practical Machine Learning application of NumPy is to compute the mean squared error for regression, as briefly shown in the first Introduction to Machine Learning lectures.
Fortunately, the official NumPy tutorial already has this example covered, so there is no point for me to reproduce it just for the sake of it (lazy!)
So please just look at the example on the official tutorial to see how you would implement this.