Python Data Structures and Algorithms

Higher order functions

Functions that take other functions as arguments, or that return functions, are called higher order functions. Python 3 contains two built-in higher order functions, filter() and map(). Note that in earlier versions of Python, these functions returned lists; in Python 3, they return an iterator, making them much more efficient. The map() function provides an easy way to transform each item into an iterable object. For example, here is an efficient, compact way to perform an operation on a sequence. Note the use of the lambda anonymous function:

Similarly, we can use the filter built-in function to filter items in a list: ...