8.2 Using the finite iterators

The itertools module provides a number of functions that we can use to produce finite sequences of values. We’ll look at 10 functions in this module, plus some related built-in functions:

• enumerate(): This function is actually part of the __builtins__ package, but it works with an iterator and is very similar to functions in the itertools module.

• accumulate(): This function returns a sequence of reductions of the input iterable. It’s a higher-order function and can do a variety of clever calculations.

• chain(): This function combines multiple iterables serially.

• groupby(): This function uses a function to decompose a single iterable into a sequence of iterables over subsets of the input data.

• zip_longest(): This function combines elements from multiple iterables. The built-in zip() function truncates the sequence at the length of the shortest iterable. The zip_longest() function pads the shorter iterables with the given fill value.

• compress...