Python Zip
To start we’re going to create a simple dataframe in python:
If you want to watch a YouTube video based around the tutorial there is one embedded slightly below.
Example 1
In this basic example, we have two lists. One for jersey numbers and another for quarterbacks. We will then zip these together in the final list.
fb_jersey_numbers = [14, 60, 16] quarterbacks = ['Y.A. Tittle', 'Otto Graham', 'George Blanda'] The order matters, so make sure you pass in the list first you want to appear in the front of each tuple.
zipped = zip(fb_jersey_numbers, quarterbacks) print(list(zipped)) [(14, ‘Y.A. Tittle’), (60, ‘Otto Graham’), (16, ‘George Blanda’)]
Example 2 - Length Mismatch
If the iterables have different lengths, zip() will stop creating tuples when the shortest iterable is exhausted.
Our list on baseball jersey numbers will have 3 examples whereas players will have 4.
basseball_jersey_numbers = [44, 32, 24] players = ['Hank Aaron', 'Sandy Koufax', 'Willie Mays', 'Al Kaline',] zipped = zip(basseball_jersey_numbers, players) print(list(zipped)) [(44, ‘Hank Aaron’), (32, ‘Sandy Koufax’), (24, ‘Willie Mays’)]
Example 3 - Mismatch no Value
While the previous example cut out Al Kaline, we can have the mismatch still appear in the final result. We have to import in zip longest first.
from itertools import zip_longest We can define what the missing value(s) can be filled with. In this case though I only passed in None.
zipped_short = zip_longest(basseball_jersey_numbers, players, fillvalue=None) print(list(zipped_short)) [(44, ‘Hank Aaron’), (32, ‘Sandy Koufax’), (24, ‘Willie Mays’), (None, ‘Al Kaline’)]
Example 4 - 3 iterables
While the past examples were based around 2 iterables, let’s take a look at an example with 3. In this one we will look at combining pitchers, teams, and strikeouts.
pitchers = ['Tom Seaver', 'Nolan Ryan', 'Phil Niekro'] teams = ['New York Mets', 'California Angels', 'Atlanta Braves'] strikeouts = [243, 186, 195] zipped = zip(pitchers, teams, strikeouts) print(list(zipped)) [(‘Tom Seaver’, ‘New York Mets’, 243), (‘Nolan Ryan’, ‘California Angels’, 186), (‘Phil Niekro’, ‘Atlanta Braves’, 195)]
Example 5 - Zip for Loop
Zip is quite common to use within for loops (any by extension list/dictionary comprehension). Let’s look at an example where we create a new list called total_contributions which is the sum of points and assists.
points = [30, 24, 35] assists = [8, 12, 10] total_contribution = [] The For loop uses both pts for points list and ast for assists list. We use zip and then append the result of adding pts + ast.
for pts, ast in zip(points, assists): total_contribution.append(pts + ast) print(total_contribution) [38, 36, 45]
Example 6 - List Comprehension
We can also look at element wise min or max. This is probably easiest to accomplish by using zip inside list comprehension.
seaver_strikeouts = [251, 201, 243] ryan_strikeouts = [383, 367, 186] min_strikeouts = [min(seaver, ryan) for seaver, ryan in zip(seaver_strikeouts, ryan_strikeouts)] print(min_strikeouts) [251, 201, 186]
Example 7 - Dictionary Creation
keys = ['name', 'wickets', 'number'] values = ['Shane Warne', 708, 23] We zip the two lists together and then use that as the parameter for dict()
warne_dict = dict(zip(keys, values)) print(warne_dict) {‘name’: ‘Shane Warne’, ‘wickets’: 708, ‘number’: 23}
Example 8 - Interleaving lists
numbers = [10, 18, 23] players = ['Sachin Tendulkar', 'Virat Kohli', 'Shane Warne'] interleaved = [item for pair in zip(numbers, players) for item in pair] print(interleaved) [10, ‘Sachin Tendulkar’, 18, ‘Virat Kohli’, 23, ‘Shane Warne’]
Example 9 - Modify Elements
Inside zip you can also modify elements. Let’s add 10 each element in strikeouts through list comprehension.
names = ['Bob Lemon', 'Mickey McDermott', 'Earl Wilson'] strikeouts = [162, 155, 149] for name, strikeout in zip(names, [k + 10 for k in strikeouts]): print(f"{name} now has {strikeout} strikeouts") Bob Lemon now has 172 strikeouts
Mickey McDermott now has 165 strikeouts
Earl Wilson now has 159 strikeouts
Example 10 - Unzip
While this is a zip tutorial, might as well showcase what Unzip does. This is the opposite of zip as we remove the paired tuples within the list.
zipped = [('Aaron Judge', 52), ('Giancarlo Stanton', 59), ('Joey Votto', 36)] players, home_runs = zip(*zipped) print(players) (‘Aaron Judge’, ‘Giancarlo Stanton’, ‘Joey Votto’)
print(home_runs) (52, 59, 36)
