Is there a zip-like method in .Net?

Question

In Python there is a really neat function called zip which can be used to iterate through two lists at the same time:

list1 = [1, 2, 3]
list2 = ["a", "b", "c"]
for v1, v2 in zip(list1, list2):
    print v1 + " " + v2

The above code should produce the following:

1 a
2 b
3 c

I wonder if there is a method like it available in .Net? I'm thinking about writing it myself, but there is no point if it's already available.

Answer 1

Update: It is built-in in C# 4 as System.Linq.Enumerable.Zip Method

Here is a C# 3 version:

IEnumerable<TResult> Zip<TResult,T1,T2>
    (IEnumerable<T1> a,
     IEnumerable<T2> b,
     Func<T1,T2,TResult> combine)
{
    using (var f = a.GetEnumerator())
    using (var s = b.GetEnumerator())
    {
        while (f.MoveNext() && s.MoveNext())
            yield return combine(f.Current, s.Current);
    }
}

Dropped the C# 2 version as it was showing its age.

Answer 2

As far as I know there is not. I wrote one for myself (as well as a few other useful extensions and put them in a project called NExtension on Codeplex.

Apparently the Parallel extensions for .NET have a Zip function.

Here's a simplified version from NExtension (but please check it out for more useful extension methods):

public static IEnumerable<TResult> Zip<T1, T2, TResult>(this IEnumerable<T1> source1, IEnumerable<T2> source2, Func<T1, T2, TResult> combine)
{
    using (IEnumerator<T1> data1 = source1.GetEnumerator())
    using (IEnumerator<T2> data2 = source2.GetEnumerator())
        while (data1.MoveNext() && data2.MoveNext())
        {
            yield return combine(data1.Current, data2.Current);
        }
}

Usage:

int[] list1 = new int[] {1, 2, 3};
string[] list2 = new string[] {"a", "b", "c"};

foreach (var result in list1.Zip(list2, (i, s) => i.ToString() + " " + s))
    Console.WriteLine(result);