Zip Two Lists Together in Python

In Python, the zip() function is used to combine two or more lists element-wise, creating tuples containing elements from corresponding positions in the input lists.

Examples

1. Using zip() to Combine Two Lists

The zip() function pairs corresponding elements from two lists into tuples.

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# Defining two lists
names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]

# Zipping the two lists together
zipped_list = list(zip(names, ages))

# Printing the zipped list
print("Zipped List:", zipped_list)

In this example:

  • names is a list containing three names.
  • ages is a list containing three corresponding ages.
  • The zip() function pairs elements at the same index from both lists into tuples.
  • The list() function converts the zip object into a readable list.

Output:

Zipped List: [('Alice', 25), ('Bob', 30), ('Charlie', 35)]

2. Using zip() in a Loop

We can use zip() inside a For loop to iterate over two lists simultaneously.

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# Defining two lists
cities = ["New York", "Paris", "Tokyo"]
countries = ["USA", "France", "Japan"]

# Iterating using zip
for city, country in zip(cities, countries):
    print(f"{city} is in {country}")

Here:

  • cities is a list of city names.
  • countries is a list of country names.
  • zip() pairs city-country values and the loop prints them in a sentence format.

Output:

New York is in USA
Paris is in France
Tokyo is in Japan

3. Zipping Lists of Unequal Length

If the lists are of unequal length, zip() stops at the shortest list.

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# Defining two lists of different lengths
students = ["John", "Emma", "Liam", "Olivia"]
scores = [85, 90, 78]

# Zipping the lists
zipped_data = list(zip(students, scores))

# Printing the result
print("Zipped Data:", zipped_data)

In this case:

  • The students list has four elements, but scores has only three.
  • zip() stops at the third element, ignoring the extra student.

Output:

Zipped Data: [('John', 85), ('Emma', 90), ('Liam', 78)]

4. Unzipping a Zipped List

We can use the * operator to unzip a zipped list back into separate lists.

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# Zipping two lists
products = ["Laptop", "Phone", "Tablet"]
prices = [1200, 800, 500]

zipped = zip(products, prices)

# Unzipping the lists
unzipped_products, unzipped_prices = zip(*zipped)

# Printing results
print("Products:", list(unzipped_products))
print("Prices:", list(unzipped_prices))

Here:

  • The * operator unpacks the tuples inside the zipped object.
  • The original lists are retrieved by using zip(*zipped).

Output:

Products: ['Laptop', 'Phone', 'Tablet']
Prices: [1200, 800, 500]

Conclusion

The zip() function is a powerful way to pair elements from multiple lists in Python. Here are key takeaways:

  1. zip() combines two lists element-wise into tuples.
  2. It can be used in loops for parallel iteration.
  3. If lists are of unequal length, it stops at the shortest one.
  4. We can unzip a zipped list using zip(*zipped_list).