Sometimes, we'll have two collections of data that need to parallel each other. In Chapter 4, Working with Collections, we saw how the zip() function can interleave two sequences to create a sequence of pairs. In many cases, we're really trying to do something like this:

map(function, zip(one_iterable, another_iterable))

We're creating argument tuples from two (or more) parallel iterables and applying a function to the argument tuple. We can also look at it like this:

(function(x,y) for x,y in zip(one_iterable, another_iterable))

Here, we've replaced the map() function with an equivalent generator expression.

We might have the idea of generalizing the whole thing to this:

def star_map(function, *iterables)
    return (function(*args) for args in zip(*iterables))

There is a better approach that is already available to us. We don't actually need these techniques. Let's look at a concrete example of the alternate approach.

In Chapter 4, Working with Collections...