从List <string>初始化Dictionary <string，string>

Question

Easiest way to do this, perhaps from an extension method? :

var MyDic = new Dictionary<string,string>{ "key1", "val1", "key2", "val2", ...}; 

Where the dictionary winds up with entries contain key and value pairs from the simple list of strings, alternating every other string being the key and values.

Answer 1

The alternation is a bit of a pain. Personally I'd just do it longhand:

var dictionary = new Dictionary<string, string>();
for (int index = 0; index < list.Count; index += 2)
{
    dictionary[list[index]] = list[index + 1];
}

You definitely can do it with LINQ, but it would be more complicated - I love using LINQ when it makes things simpler, but sometimes it's just not a great fit.

(Obviously you can wrap that up into an extension method.)

Note that you can use dictionary.Add(list[index], list[index + 1]) to throw an exception if there are duplicate keys - the above code will silently use the last occurrence of a particular key.

Answer 2

You can use a range that is half the length of the list, and ToDictionary to create the dictionary from items from the list:

Dictionary<string, string> dictionary =
  Enumerable.Range(0, list.Count / 2)
  .ToDictionary(i => list[i * 2], i => list[i * 2 + 1]);

Answer 3

LINQ and GroupBy version:

var dict = source.Select((s, i) => new { s, i })
                 .GroupBy(x => x.i / 2)
                 .ToDictionary(g => g.First().s, g => g.Last().s);

Answer 4

If you need LINQ - you can Zip list to itself first:

var result = list.Where((item, id) => id % 2 == 0)
     .Zip (list.Where((item, id) => id % 2 == 1), 
          (key, value) => new KeyValuePair<string,string>(key, value))
     .ToDictionary(p => p.Key, p => p.Value);