Comparing strings in 2 list using Linq

Question

I need to compare to list with strings, and find whitch elements that are similar. ie.

List<string> listA = {"ProfileHeight", "ProfileWidth", "WebThickness"}
List<string> listB ={"ProfileHeightVisibility", "ProfileWidthVisibility", "WebThicknessVisibility", "FlangeThicknessVisibility", "DepthVisibility"}

I was wondering if it is possible to use Linq. I want the result to be a list with the elements from ListB that have a name similar to the strings in listA. Where the statemant i.e. "ProfileHeightVisibility.Contains("ProfileHeight") = true

And by "similar" you mean StartsWith or Contains?

Corak
– Corak

2013-07-30 08:10:29 +00:00
Commented Jul 30, 2013 at 8:10 — Corak
– Corak, Commented Jul 30, 2013 at 8:10

lc. · Accepted Answer · 2013-07-30 08:10:36Z

20

You mean you want items in listB where it contains any of the elements in listA?

listB.Where(b => listA.Any(a => b.Contains(a))

answered Jul 30, 2013 at 8:10

lc.

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Comments

Matthias Meid · Accepted Answer · 2013-07-30 08:10:55Z

5

You can do it in LINQ:

listB.Where(e => listA.Any(a => e.Contains(a)));

Bear in mind that this algorithm has a runtime cost similar to O(n^2), it will therefore slow down quickly as the number of elements in your lists grows.

answered Jul 30, 2013 at 8:10

Matthias Meid

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Swift · Accepted Answer · 2013-07-30 08:20:34Z

1

You can also implement things like that :

  public class EqualityComparer : IEqualityComparer<string>
  {

    public bool Equals(string x, string y)
    {
      return y.Contains(x);
    }

    public int GetHashCode(string obj)
    {
      return 1;
    }
   }

and then use intersect like that:

 listB.Intersect(listA, new EqualityComparer()).ToList();

answered Jul 30, 2013 at 8:20

Swift

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Zin Min · Accepted Answer · 2018-10-10 10:04:12Z

1

List<string> listA = new List<string> { "zinmin", "zin1", "zin2" };
List<string> listB = new List<string> { "zinmin", "min1", "min2" };



List<string> matching = listA.Intersect(listB).ToList();

matching result will come {"zinmin"} . Sorting order doesn't matter.

answered Oct 10, 2018 at 10:04

Zin Min

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toszo · Accepted Answer · 2013-07-30 11:54:59Z

0

Yes you can do such thing with LINQ

    public List<string> GetSimilarStrings(List<string> list1, List<string> list2)
    {
        return (from item in list1 from item2 in list2 where string.Equals(item,item2,StringComparison.InvariantCultureIgnoreCase) select item).ToList();
    }

edited Jul 30, 2013 at 11:54

answered Jul 30, 2013 at 8:13

toszo

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4 Comments

Matthias Meid Over a year ago

Why do you use string.Compare? This method returns an integer stating the lexical order of two strings rather than a boolean, does it not?

toszo Over a year ago

Yeah, good point. I corrected my answer. Comparing strings by "==" could cause problems with culture, encoding or case sensitiveness of words. This example shows how to handle those things.

Matthias Meid Over a year ago

I'm not sure whether the strings are supposed to be equal. However, I'd maybe rather use string.Equals(a, b, StringComparision.InvariantCultureIgnoreCase) msdn.microsoft.com/en-us/library/t4411bks.aspx

toszo Over a year ago

You are right, it could be even better to use String.Equals.

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