How to Zip Arrays in Ruby: Syntax and Examples

In Ruby, you can zip arrays using the zip method, which combines elements from multiple arrays into a single array of arrays. Each sub-array contains elements from the input arrays at the same index.

Syntax

The zip method is called on one array and takes one or more arrays as arguments. It returns a new array where each element is an array containing elements from the original arrays at the same position.

• array1.zip(array2, array3, ...)
• Returns an array of arrays combining elements by index.

ruby

array1.zip(array2)

Example

This example shows how to zip two arrays of equal length. The result is an array of pairs where each pair contains elements from both arrays at the same index.

ruby

names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]
combined = names.zip(ages)
puts combined.inspect

Output

[["Alice", 25], ["Bob", 30], ["Charlie", 35]]

Common Pitfalls

A common mistake is expecting zip to fill missing values if arrays have different lengths. Ruby fills missing elements with nil. Also, zip does not modify the original arrays unless you use zip!.

ruby

a = [1, 2]
b = ["x", "y", "z"]
result = a.zip(b)
puts result.inspect

# Wrong: expecting no nils
# Right: nil appears for missing elements

# Also, zip does not change original arrays:
a.zip(b)
puts a.inspect

Output

[[1, "x"], [2, "y"], [nil, "z"]]
[1, 2]

Quick Reference

Method	Description
zip(array2, ...)	Combines elements from arrays by index into sub-arrays
zip!(array2, ...)	Modifies the original array by zipping with others
zip with block	Processes zipped elements with a block instead of returning array

Key Takeaways

Use zip to combine arrays element-wise into an array of arrays.

If arrays differ in length, missing elements become nil in the result.

zip returns a new array; use zip! to modify the original array.

You can pass multiple arrays to zip to combine more than two arrays.

Using a block with zip lets you process elements directly without creating a new array.