Map two lists into a dictionary in C#

With .NET 4.0 (or the 3.5 version of System.Interactive from Rx), you can use Zip():

var dic = keys.Zip(values, (k, v) => new { k, v })
              .ToDictionary(x => x.k, x => x.v);

Or based on your idea, LINQ includes an overload of Select() that provides the index. Combined with the fact that values supports access by index, one could do the following:

var dic = keys.Select((k, i) => new { k, v = values[i] })
              .ToDictionary(x => x.k, x => x.v);

(If values is kept as List<string>, that is...)

I like this approach:

var dict =
   Enumerable.Range(0, keys.Length).ToDictionary(i => keys[i], i => values[i]);

If you use MoreLINQ, you can also utilize it's ToDictionary extension method on previously created KeyValuePairs:

var dict = Enumerable
    .Zip(keys, values, (key, value) => KeyValuePair.Create(key, value))
    .ToDictionary();

It also should be noted that using Zip extension method is safe against input collections of different lengths.

Map two lists into a dictionary in C#

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