*48*

Often you might be interested in zipping (or “merging”) together two lists in Python. Fortunately this is easy to do using the zip() function.

This tutorial shows several examples of how to use this function in practice.

**Example 1: Zip Two Lists of Equal Length into One List**

The following syntax shows how to zip together two lists of equal length into one list:

#define list a and list b a = ['a', 'b', 'c']b = [1, 2, 3] #zip the two lists together into one listlist(zip(a, b)) [('a', 1), ('b', 2), ('c', 3)]

**Example 2: Zip Two Lists of Equal Length into a Dictionary**

The following syntax shows how to zip together two lists of equal length into a dictionary:

#define list of keys and list of valueskeys = ['a', 'b', 'c'] values = [1, 2, 3] #zip the two lists together into one dictionarydict(zip(keys, values)) {'a': 1, 'b': 2, 'c': 3}

**Example 3: Zip Two Lists of Unequal Length**

If your two lists have unequal length, zip() will truncate to the length of the shortest list:

#define list a and list b a = ['a', 'b', 'c', 'd']b = [1, 2, 3] #zip the two lists together into one listlist(zip(a, b)) [('a', 1), ('b', 2), ('c', 3)]

If you’d like to prevent zip() from truncating to the length of the shortest list, you can instead use the zip_longest() function from the **itertools** library.

By default, this function fills in a value of “None” for missing values:

from itertools import zip_longest #define list a and list b a = ['a', 'b', 'c', 'd']b = [1, 2, 3] #zip the two lists together without truncating to length of shortest listlist(zip_longest(a, b)) [('a', 1), ('b', 2), ('c', 3), ('d', None)]

However, you can use the **fillvalue **argument to specify a different fill value to use:

#define list a and list b a = ['a', 'b', 'c', 'd']b = [1, 2, 3] #zip the two lists together, using fill value of '0'list(zip_longest(a, b, fillvalue=0)) [('a', 1), ('b', 2), ('c', 3), ('d', 0)]

*You can find the complete documentation for the zip_longest() function here.*