Chapter 8. The Itertools Module

Functional programming emphasizes stateless programming. In Python this leads us to work with generator expressions, generator functions, and iterables. In this chapter, we'll look at the itertools library with numerous functions to help us work with iterable collections.

We introduced iterator functions in Chapter 3, Functions, Iterators, and Generators. In this chapter, we'll expand on that superficial introduction. We used some related functions in Chapter 5, Higher-order Functions.

Note

Some of the functions merely behave like they are proper, lazy Python iterables. It's important to look at the implementation details for each of these functions. Some of them create intermediate objects, leading to the potential of consuming a large amount of memory. Since implementations might change with Python releases, we can't provide function-by-function advice here. If you have performance or memory issues, ensure that you check the implementation...