Using .ToDictionary()

Question

I have a method returning a List, let's call it GetSomeStrings().

I have an extension method on string class, returning number of characters in the string, eg. myString.Number('A').

I would like to, in a single line, grab a dictionary. An entry of the dictionary contains the string, and the number of a chosen character in the string.

Actually I do the following:

var myDic = GetSomeStrings().ToDictionary(x=>x.Number('A')); 

which gives me a dictionary <int,string>; I would like the key as the string.

After, I'd like to order the dictionary on the int value. It is possible to include this in the previous statement ?

I'd really like to avoid a collection enumeration to sort or create the dictionary from the list, which is what i do actually without troubles. Thank you for your optimization help !

Answer 1

Edit

The ToDictionary() method has an overload that takes two lambda expressions _{(nitpick: delegates)}; one for the key and one for the value.

For example:

var myDic = GetSomeStrings().ToDictionary(x => x, x => x.Number('A')); 

Note that the values returned by GetSomeStrings() must be unique.

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.Net's Dictionary<TKey, TValue> is unordered; it cannot be sorted at all.

Instead, you can sort the dictionary when you use it, like this:

foreach(KeyValuePair<string, int> kvp in dict.OrderBy(kvp => kvp.Value)) 

Answer 2

A regular Dictionary is not sorted, but you can use a SortedDictionary:

var sortedDict = new SortedDictionary<string, int>(     GetSomeStrings().ToDictionary(x => x, y => y.Number('A'))); 

That should give you a SortedDictionary<string, int> sorted by the string key.