Merge List objects

Question

I have an asp.net application where I have 4 List collection objects

List<string> sTransID = new List<string>();
List<string> sOriginID = new List<string>();
List<string> sDestID = new List<string>();
List<string> sCourierID = new List<string>();

These objects are populated at different sections of the application (inside a class, or an aspx code behind etc). The page performance is significantly slow when List elements size increase.

What would be the fastest way to loop through these objects when reading their values (in order to avoid having to loop through 4 objects) ? Can I merge these objects into a parent List object and loop through the parent?

Update:
By merge, I mean something like:

var Parent = List<sTransID>, List<sOriginID>, List<sDestID>, List<sCourierID>  
var GetLocation = Parent[0];  // will return TransID[0], Origin[0], DestID[0], CourierID[0]

Is it faster? Probably just a little bit. If **search** is your bottle neck then you should use a better data structure (better = more efficient for searching). Hastable or (when applicable) an ordered list — Adriano Repetti, Sep 16 '13 at 15:55
`sTransID.Union(sOriginID.Union(sDestID.Union(sCourierID)))` ? — I4V, Sep 16 '13 at 15:55
I don't think merging into one big list would have much impact; especially if the lists are large. What are you doing with these strings once you loop over them? — Buh Buh, Sep 16 '13 at 15:59
Your poor choice of title got your question closed. Your title should have included your real question, "What would be the fastest way to loop through these objects when reading their values?" — Buh Buh, Sep 16 '13 at 16:16
@BuhBuh ... store them in a database then pass to an API, then display on screen — Csharp, Sep 16 '13 at 16:20

score 0 · Answer 1 · answered Sep 16 '13 at 15:55

I have an Extension method that merges dictionaries. It might be of some help if you modify it for Lists.

public static class DictionaryExtensions
{
    public static T MergeLeft<T, K, V>(this T me, params IDictionary<K, V>[] others)
        where T : IDictionary<K, V>, new()
    {
        var newMap = new T();

        foreach (var p in (new List<IDictionary<K, V>> { me }).Concat(others).SelectMany(src => src))
        {
            newMap[p.Key] = p.Value;
        }

        return newMap;
    }

}

used as follows:

var mergedDictionary = new Dictionary<string, string>().MergeLeft(dic1, dic2, dic3);

score 0 · Answer 2 · answered Sep 16 '13 at 15:56

0

One way would be to just concat the lists together before looping:

var itemsToLoop = sTransID.Concat(sOriginID).Concat(sDestID).Concat(sCourierID);

answered Sep 16 '13 at 15:56

Jamie Dixon

53,019
19
125
162

Merge List objects

2 Answers2