Question

I have a lambda expression that gets results from a Dictionary.

var sortedDict = (from entry in dctMetrics 
                  orderby entry.Value descending 
                  select entry);

The expression pulls back the pairs I need, I can see them in the IDE’s debug mode.

How do I convert this back a dictionary of the same type as the source? I know sortedDict’s TElement is a KeyValuePair, but I am having trouble fully understanding the ToDictionary extension method’s syntax. I also tried foreach’ing the var result to piecewise construct a new dictionary, but to no avail.

Is there something like this (functionality wise):

var results = (from entry in dictionary 
               orderby entry.Value descending 
               select entry);
Dictionary<string,float> newDictionary = results as (Dictionary<string,float>);

Answer 1

You can do it like this:

var newDictionary = results.ToDictionary(r => r.Key, r => r.Value);

Read that as “for each pair in results, add that element to the new dictionary, where the key will be produced as the key of the pair, and the value will be produced as the value of the pair.”

Also, just based on your sample code — you should keep in mind that a Dictionary<T, U> is implemented as a hash table, so it won’t maintain the order of the elements you put into it. Consider using a SortedDictionary or a SortedList instead if you need an ordered map.