Zip for combining arrays in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the zip method do in Ruby?

The zip method combines elements from two or more arrays into a single array of arrays, pairing elements with the same index together.

intermediate

How does zip handle arrays of different lengths?

If arrays have different lengths, zip fills missing elements with nil for shorter arrays.

beginner

Example: What is the result of [1, 2, 3].zip([4, 5, 6])?

The result is [[1, 4], [2, 5], [3, 6]]. Each element from the first array is paired with the element at the same index from the second array.

intermediate

Can zip combine more than two arrays?

Yes, zip can combine multiple arrays by passing them as arguments. It pairs elements from all arrays by their index.

advanced

How can you use zip with a block?

You can pass a block to zip to process each combined array immediately. The block receives each paired array as an argument.

What does [1, 2].zip([3, 4]) return?

A [[1, 3], [2, 4]]

B [[1, 2], [3, 4]]

C [[1, 3, 4], [2]]

D [[1, 3], [2]]

zip pairs elements by index, so it returns [[1, 3], [2, 4]].

What happens if arrays have different lengths in zip?

A It fills missing elements with nil.

B It raises an error.

C It ignores extra elements.

D It repeats elements from the shorter array.

Ruby fills missing elements with nil when arrays have different lengths.

How do you combine three arrays a, b, and c using zip?

A a.zip(b).map(c)

B a.zip(b).zip(c)

C zip(a, b, c)

D a.zip(b, c)

You pass multiple arrays as arguments: a.zip(b, c).

What does this code output?<br>[1, 2].zip([3, 4]) { |x| p x }

A Raises an error

B Prints [1, 3] and [2, 4], returns nil

C Returns [[1, 3], [2, 4]] without printing

D Prints [1, 3] and [2, 4], returns [[1, 3], [2, 4]]

The block prints each pair, but zip returns the original array when a block is given.

Which method pairs elements from arrays by their index?

A flatten

B concat

C zip

D map

zip pairs elements from arrays by their index.

Explain how the zip method works to combine arrays in Ruby.

Think about matching elements from each array by their position.

Describe how you can use a block with zip and what effect it has.

Consider what happens inside the block and the method's return value.