The zip function

It’s often necessary to iterate over multiple lists simultaneously. Suppose we’re keeping score of a game and we have two lists, one of names and one of scores:

>>> names = ["Bob", "Alice", "Eve"]
>>> scores = [42, 97, 68]

The zip function takes any number of iterable arguments and steps through all of them at the same time until the end of the shortest iterable has been reached:

>>> for name, score in zip(names, scores):
>>>     print(f"{name} had a score of {score}.")
...
Bob had a score of 42.
Alice had a score of 97.
Eve had a score of 68.

What will the above loop print after removing the last element from scores?

>>> scores.pop(-1)
68
>>> for name, score in zip(names, scores):
>>>     print(f"{name} had a score of {score}.")
...
Bob had a score of 42.
Alice had a score of 97.

The loop terminates even though there are more values in names. Here, Eve isn’t included because scores only has two elements.

We can also use zip() to quickly and easily create a dict from two lists. For example:

>>> score_dict = dict(zip(names, scores))
>>> print(score_dict)
{'Bob': 42, 'Alice': 97, 'Eve': 68}