.NET 4.0 Generics

Time for action – flattening a dictionary

Suppose, we have a dictionary such that each key has a list of values attached to them. Now, we want to project all the elements in a single collection:

1. Copy the following code snippet as a query to LINQPad:

   Dictionary<string, List<string>> map = new Dictionary<string, List<string>>();
   
   map.Add("UK", new List<string>() { "Bermingham", "Bradford", "Liverpool" });
   map.Add("USA", new List<string>() { "NYC", "New Jersey", "Boston", "Buffalo" });
   
   var cities = map.SelectMany(c => c.Value).ToList();
   cities.Dump("All Cities");

2. Run the query. You should see the following output:
   

What just happened?

In this example, ...