Sorting a NameValueCollection by value in c#

Question

I have a NameValueCollection and I would like to sort this on his value. Does anyone got some ideas how to do this easely? I was thinking to wrap it into a SortedList or SortedDictionairy but I'm not sure how to get started.

Thijs

Why not just call [`OrderBy`](http://msdn.microsoft.com/en-us/library/bb534966.aspx) on your collection? — Roman, Oct 18 '11 at 15:05
Can't you use SortedDictionary or SortedList instead? Than it would be pretty easy: http://stackoverflow.com/questions/289/how-do-you-sort-a-c-sharp-dictionary-by-value , http://stackoverflow.com/questions/1250281/c-sharp-how-to-sort-a-sorted-list-by-its-value-column — Pieter, Oct 18 '11 at 15:06
@Pieter , That's the post I was looking for but didn't found! Thank you! — Thijs, Oct 18 '11 at 15:07

score 4 · Accepted Answer · answered Oct 18 '11 at 15:04

4

Using LINQ:

var sorted = nvc.OrderBy(kvp => kvp.Value);

answered Oct 18 '11 at 15:04

Oded

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Ok, this seems easy but I don't realy understand how to make that into a Collection.. Could you extend your code a bit please? – Thijs Oct 18 '11 at 15:05
1

@Thijs - `sorted` is a collection. – Oded Oct 18 '11 at 15:07
@Thijs - Is there a problem with my answer? – Oded Oct 28 '11 at 13:07
@Thijs - No, it doesn't. That's why I said use `LINQ`. You need to add a `using System.Linq;` directive to the file. The `OrderBy` extension method is defined there. – Oded Oct 28 '11 at 13:39
Oh that makes sense. I'll use that :) – Thijs Oct 28 '11 at 13:41
This isn't quite correct, since NameValueCollection does not contain KeyValuePair<,>. – Mike Henry Jul 28 '12 at 23:03

Mike Henry · Answer 2 · 2012-07-29T01:24:10.787

I think the complexity of the solution depends on whether you care about multiple values per key. If you only need to sort the first value per key, the following should return the sorted result as an IEnumerable<KeyValuePair<string, string>>:

var sorted = nvc.AllKeys.OrderBy(key => nvc[key])
                .Select(key => new KeyValuePair<string, string>(key, nvc[key]));

If you care about multiple values per key, you may have to split each value into a KeyValuePair before sorting them. Something like:

var sorted = nvc.AllKeys
                .SelectMany(key =>
                    nvc.GetValues(key)
                       .Select(val => new KeyValuePair<string, string>(key, val)))
                .OrderBy(kvp => kvp.Value);

Examples:

Given:

var nvc = new NameValueCollection() {
    { "key1", "c" },
    { "key1", "a" },
    { "key2", "b" }
};

The first example should return the following IEnumerable<KeyValuePair<string, string>>:

key2: b
key1: c,a

The second example should return the following IEnumerable<KeyValuePair<string, string>>:

key1: a
key2: b
key1: c

Sorting a NameValueCollection by value in c#

2 Answers2

Examples: