Creating arrays

A NumPy array is a grid of numbers of one type, built for fast maths.

• np.array([1, 2, 3]) turns a list into an array.
• np.zeros(3), np.ones((2, 3)) and np.arange(0, 10, 2) make arrays quickly.
• np.linspace(0, 1, 5) gives 5 evenly spaced numbers.

import numpy as np
print(np.arange(0, 10, 2).tolist(), np.zeros(3).tolist())

[0, 2, 4, 6, 8] [0.0, 0.0, 0.0]

Remember: import numpy as np, then build arrays with np.something().

Common mistake: Expecting np.arange(0, 10, 2) to include 10. Like range, it stops before the end.