Universal Functions (ufuncs)

What is a ufunc?

A ufunc (universal function) is a function that operates on ndarrays element-by-element. They are written in C and are the reason NumPy is fast.

Why ufuncs over Loops?

A Python for loop has to check types and dispatch functions on every single iteration. A ufunc pushes the loop down to C, bypassing Python overhead entirely.

Common ufuncs

Aggregations

ufuncs have methods to collapse arrays:

arr = np.array([1, 2, 3, 4])
arr.sum()
arr.mean()
arr.cumsum() # Cumulative sum: [1, 3, 6, 10]