Zip

The C# Zip extension method acts upon 2 collections. It processes each element in 2 series together. Zip() is found in System.Linq, so we must include this namespace.

Func info

With a Func instance, we use Zip to handle elements from two collections in parallel. Any IEnumerable can be zipped.

Example

We declare 2 string arrays. Then, we invoke the Zip method. The first argument to the Zip method is the secondary array we want to process in parallel.

using System;
using System.Linq;

// Two source arrays.
var array1 = new string[] { "blue", "red", "green" };
var array2 = new string[] { "sky", "sunset", "lawn" };

// Concatenate elements at each position together.
var zip = array1.Zip(array2, (a, b) => (a + "=" + b));

// Look at results.
foreach (var value in zip)
{
    Console.WriteLine("ZIP: {0}", value);
}
ZIP: blue=sky
ZIP: red=sunset
ZIP: green=lawn

Unequal counts

If you happen to have 2 collections with an unequal number of elements, the Zip method will only continue to the shortest index where both elements exist.

using System;
using System.Linq;

var test1 = new int[] { 1, 2 };
var test2 = new int[] { 3 };
// Zip unequal collections.
var zip = test1.Zip(test2, (a, b) => (a + b));
foreach (var value in zip)
{
    Console.WriteLine(value);
}
4

A summary

Zip() processes 2 collections or series in parallel. This can replace a lot of for-loops where the index variable is necessary to process 2 arrays at once.