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 str

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

You need to use the overload of ToDictionary which takes two functions:

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

Both functions take what ever object you are using to create the dictionary. The first produces the Key; the second, the Value.

Answer 3

To construct your dictionary, you can do this:

var strings = new[] { "one", "2", "three", "four", "five", "six", "seven", "eight", "nine", "ten" };
var dictionary = strings.GroupBy(x => x.Length.ToString()).ToDictionary(x => x.Key, x => x);

Notice the "ToString()" usage to turn the Length of the string into a string.

Also, sorting a dictionary doesn't generally make sense. You can sort the items in each key of the dictionary, or you can sort the keys of the dictionary when you want to loop through them.

var sortedKeys = dictionary.Keys.OrderBy(x => x);
var sortedValues = dictionary["1"].OrderBy(x => x);

Answer 4

If I understand the question correctly, here is my solution:

var myDic = GetSomeStrings()
.Select(x => new KeyValuePair<string, int>(x, x.Number('A')))
.ToDictionary(t => t.Key, t => t.Value);

Answer 5

A regular Dictonary is not sorted, but you can use a SortedDictonary:

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

That statement should give you a SortedDictionary sorted by the string key.

Answer 6

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

Gets you the dictionary in your intended way.

Edit: Added Order by. First orders the strings, then puts them into the dict, as you liked

Edit2: Slaks is right. OrderBy would have no effect. Removed it again