I have a Hashtable with following content:
jak: 1
dsf: 1
usd: 1
idb: 1
bla: 3
sdd: 1
asd: 2
bsd: 1
I want to select top 10 pairs by value. In this example it would be like that:
bla: 3
asd: 2
etc. How do I do that?
Asked
Active
Viewed 91 times
-2
Theodor Zoulias
- 34,835
- 7
- 69
- 104
Richard
- 11
- 2
-
1If you're getting the top 10, why wouldn't the result have _all_ the values from the input? – gunr2171 Aug 24 '21 at 16:15
-
@gunr2171 i have a lot more pairs, i just didnt wanna put them all in, besides i still need them sorted. – Richard Aug 24 '21 at 16:16
-
1Why are you using a HashTable rather than a Dictionary? Because Dictionaries are generic you can easily do this with Linq. – gunr2171 Aug 24 '21 at 16:17
-
@gunr2171 i will try that, thanks! – Richard Aug 24 '21 at 16:20
-
To make the example consistent with the question asked, you should probably edit the question like this: *"I want to select top **2** pairs..."* – Theodor Zoulias Aug 24 '21 at 17:05
1 Answers
0
If you swap your code to using a dictionary, it'll look like:
var top10 = dict.OrderByDescending(kvp => kvp.Value).Take(10);
You can enumerate top10, which will be a sequence of KeyValuePair, and print their Key and Value properties
You can still do it with a hashtable, by the way (gunr's comment kinda implies that you can't use LINQ) and you can get LINQ to Cast all the entries to make them easier to work with:
hashtable.Cast<DictionaryEntry>().OrderByDescending(de => (int)de.Value).Take(10)
Caius Jard
- 72,509
- 5
- 49
- 80
-
-
I would't use Hashtable for new development. In either case this is going to be fairly slow, relatively speaking, because you're sorting potentially a lot of items to discard most. The alternatives are fairly intense though. If you have a specific performance requirement, state it as part of the inquiry. All in i think you'll have to get a very long list before it becomes an issue.. If your question is about raw performance of the dictionary vs hashtable as a data storage device maybe see https://stackoverflow.com/questions/1089132/net-hashtable-vs-dictionary-can-the-dictionary-be-as-fast – Caius Jard Aug 24 '21 at 16:35