When using the max(), min(), and sorted() functions, we have an optional key= parameter. The function provided as an argument value modifies the behavior of the higher-order function. In many cases, we used simple lambda forms to pick items from a tuple. Here are two examples we heavily relied on:

fst = lambda x: x[0]
snd = lambda x: x[1]

These match built-in functions in other functional programming languages.

We don't really need to write these functions. There's a version available in the operator module which describes these functions.

Here's some sample data we can work with:

>>> year_cheese = [(2000, 29.87), (2001, 30.12), (2002, 30.6), (2003, 30.66), (2004, 31.33), (2005, 32.62), (2006, 32.73), (2007, 33.5), (2008, 32.84), (2009, 33.02), (2010, 32.92)]

This is the annual cheese consumption. We used this example in Chapter 2, Introducing Some Functional Features and Chapter 9, More Itertools Techniques.

We can locate the data point...