Count values in Dictionary using LINQ and LINQ extensions

问题

I have a dictionary that looks something like this:

Dictionary<String, List<String>>

test1 : 1,3,4,5
test2 : 2,3,6,7
test3 : 2,8

How can I get a count of all the values using LINQ and LINQ extensions?

回答1:

Let's say you have:

Dictionary<String, List<String>> dict = ...

If you want the number of lists, it's as simple as:

int result = dict.Count;

If you want the total count of all the strings in all the lists:

int result = dict.Values.Sum(list => list.Count);

If you want the count of all the distinct strings in all the lists:

int result = dict.Values
                 .SelectMany(list => list)
                 .Distinct()
                 .Count();

回答2:

How about

yourdictionary.Values.Sum(l => l.Count);

回答3:

In case you want to count each item separately:

dict.Values.SelectMany(s => s).GroupBy(s => s)
    .Select(g => new {Value = g.First(), Count = g.Count});

With your sample you'll get:

"1", 1; "3", 2; "4", 1; "5", 1, "6", 1; "7", 1; "8", 1

来源：https://stackoverflow.com/questions/11954608/count-values-in-dictionary-using-linq-and-linq-extensions