Using an immutable namedtuple as a record

In Chapter 3, Functions, Iterators, and Generators, we showed two common techniques to work with tuples. We've also hinted at a third way to handle complex structures. We can do any of the following, depending on the circumstances:

• Use lambdas (or functions) to select a named item using the index
• Use lambdas (or functions) with *parameter to select an item by parameter name, which maps to an index
• Use namedtuples to select an item by attribute name or index

Our trip data, introduced in Chapter 4, Working with Collections, has a rather complex structure. The data started as an ordinary time series of position reports. To compute the distances covered, we transposed the data into a sequence of legs with a start position, end position, and distance as a nested three-tuple.

Each item in the sequence of legs looks as follows as a three-tuple:

first_leg= ((37.54901619777347, -76.33029518659048), (37.840832, -76.273834), 17.7246)

This is a short trip between...