How to sort Dictionary based on keys where key contains Month Year expression of DateTime as String

Question

I am trying to sort below Dictionary

Dictionary<string, int> map = new Dictionary<string, int>();
map["Sep 20"] = 10;
map["Oct 20"] = 11;
map["Nov 20"] = 23;
map["Jan 21"] = 15;
map["Feb 20"] = 50;
map["Mar 20"] = 23;

I have tried to used SortedDictionary to sort Dictionary as follows

SortedDictionary<string, int> sortMap = new SortedDictionary<string, int>(map);

foreach (var entry in sortMap)
{
  Console.WriteLine (entry.Key+"\t"+entry.Value);
}

This is I am expecting as output

Feb 20  50
Mar 20  23
Sep 20  10
Oct 20  11
Nov 20  23
Jan 21  15

But, I am getting actual output as follows

Feb 20  50
Jan 21  15
Mar 20  23
Nov 20  23
Oct 20  11
Sep 20  10

Answer 1

You can use DateTime.ParseExact and LINQ:

 map = map
    .Select(kv => (KV: kv, DT: DateTime.ParseExact(kv.Key, "MMM yy", CultureInfo.InvariantCulture)))
    .OrderBy(x => x.DT)
    .ToDictionary(x => x.KV.Key, x => x.KV.Value);

However, if you want to use this Dictionary<TKey, TValue> you should not rely on the order if you plan to modify it. If you add or remove items, the enumerator might return the key-value-pairs in a different order. So if you have to do this often, you better use a SortedDictionary<TKey, TValue>> or a simple List<T>(T could be a class or a KeyValuePair<TKey, TValue>).

Answer 2

Instead of struggling with sorting a string field which contains 2 values, I would go with DateTime

Dictionary<DateTime, int> map = new Dictionary<DateTime, int>();
map[new DateTime(2020,9,1)] = 10;//"Sep 20"
map[new DateTime(2020, 10, 1)] = 11;//"Oct 20"
map[new DateTime(2020, 11, 1)] = 23;//"Nov 20"
map[new DateTime(2021, 1, 1)] = 15;//"Jan 21"
map[new DateTime(2020, 2, 1)] = 50;//"Feb 20"
map[new DateTime(2020, 3, 1)] = 23;//"Mar 20"

SortedDictionary<DateTime, int> sortMap = new SortedDictionary<DateTime, int>(map);
foreach (var entry in sortMap)
{
    Console.WriteLine(entry.Key.ToString("MMM yy") + "\t" + entry.Value);
}

https://dotnetfiddle.net/ZNE39y

Answer 3

try this below code for sorting

var sortedDic=from entry in map orderby DateTime.ParseExact(entry.Key, "MMM yy", CultureInfo.InvariantCulture) ascending select entry;