Map one dictionary to another using Linq

user_2658159 0
Viewed 3083

Is there an elegant way to map one Dictionary to another using Linq in the .NET framework?

This can be accomplished via enumerating with foreach:

var d1 = new Dictionary<string, string>() {
    { "One", "1" },
    { "Two", "2" }
};

// map dictionary 1 to dictionary 2 without LINQ
var d2 = new Dictionary<string, int>();
foreach(var kvp in d1) {
    d2.Add(kvp.Value, int.Parse(kvp.Value));
}

...but I'm looking for some way to accomplish with LINQ:

// DOES NOT WORK
Dictionary<string, int> d2 =
    d1.Select(kvp => {
        return new KeyValuePair<string, int>(kvp.Key, int.Parse(kvp.Value));
    })
dictionary linq .net c#
2 Answers

Just use ToDictionary extension method from System.Linq namespace

var d2 = d1.ToDictionary(kvp => kvp.Key, kvp => int.Parse(kvp.Value));

Since Dictionary<TKey, TValue> class implements IEnumerable<KeyValuePair<TKey,TValue>> and ToDictionary is extension method for IEnumerable<T> the code above works fine

user_47286850

Please try this:

var d1 = new Dictionary<string, string>() {
    { "One", "1" },
    { "Two", "2" }
};

// map dictionary 1 to dictionary 2 with LINQ
var d2 = d1.ToDictionary(kvp => kvp.Value, kvp => int.Parse(kvp.Value));
user_57447180
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