Functional Python Programming

Chapter 9

Summary

In this chapter, we looked at a number of functions in the itertools module.
This library module provides a number of functions that help us work with iterators
in sophisticated ways.

We looked at the product() function that will compute all the possible combinations
of the elements chosen from two or more collections. The permutations() function
gives us different ways to reorder a given set of values. The combinations()
function returns all the possible subsets of the original set.

We also looked at ways in which the product() and permutations() functions
can be used naïvely to create extremely large result sets. This is an important
cautionary note. A succinct and expressive algorithm can also involve a vast amount
of computation. We must perform basic complexity analysis to be sure that the code
will finish in a reasonable amount of time.

In the next chapter, we'll look at the functools module. This module includes some
tools to work with functions as first-class objects. This builds on some material shown
in Chapter 2, Introducing Some Functional Features, and Chapter 5, Higher-order Functions.