linq on two string array
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  1. #1
    Join Date
    May 2013
    Posts
    1

    linq on two string array

    string[] listOne = new string[] { "dog", "cat", "car", "apple"};
    string[] listTwo = new string[] { "car", "apple"};

    What I need is to order listOne by the order of items in listTwo (if present). So the new list would be in this order; "car", "apple", "dog", "cat"

  2. #2
    Join Date
    Feb 2011
    Location
    United States
    Posts
    1,005

    Re: linq on two string array

    I don't know of a quick way to do it with Linq (probably because I don't use Linq terribly often, perhaps another member will know).

    You can do it normally though, if you have a way to quickly test membership in both lists.

    Code:
    List<string> orderedResult = new List<string>();
    for(int i = 0; i < listTwo.Length; i++)
        if( isMember(listTwo[i], listOne) )  //If the i'th item in list2 is contained in list1
            orderedResult.Add(listTwo[i]);
    
    for(int i = 0; i < listOne.Length; i++)
        if( !isMember(listOne[i], listTwo) ) //If the i'th item in list1 is NOT contained in list2
            ordreredResult.Add(listOne[i]);
    For short lists, it is probably sufficient to implement isMember as a loop. If you had longer lists, you'd probably want to construct a dictionary for each list:
    Code:
    Dictionary<string, int> listOneDict = new Dictionary<string, int>();
    foreach(string s in listOne)
        listOneDict.Add(s, 0);
    And then test for membership:
    Code:
    listOneDict.ContainsKey("someStringToTest");
    All of these snippets assume that listOne and listTwo have no repeated elements.

    Anyway, I think that ought to work, but I didn't explicitly test it. Push back if you need more information. Hope that is a little helpful!
    Best Regards,

    BioPhysEngr
    http://blog.biophysengr.net
    --
    All advice is offered in good faith only. You are ultimately responsible for effects of your programs and the integrity of the machines they run on.

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