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c#similarity

Implementing jaccard similarity in c#

I am trying to understand "Jaccard similarity" between 2 arrays of type double having values greater than zero and less than one.

Till now i have searched many websites for this but what I found is that the both arrays should be of same size(Number of elements in array 1 should be equal to number of elements in array 2). But I am having different number of elements in both arrays. Is there any way to implement "jaccard similarity" ?

Solution

  • Using C#'s LINQ ...

    Say you have an array of doubles named A and another named B. This will give you the Jaccard index:

    var CommonNumbers = from a in A.AsEnumerable<double>()
                    join b in B.AsEnumerable<double>() on a equals b
                    select a;
double JaccardIndex = (((double) CommonNumbers.Count()) /
                       ((double) (A.Count() + B.Count())));

    The first statement gets a list of numbers that appear in both arrays. The second computes the index - that is just the size of the intersection (how many numbers appear in both arrays) divided by the size of the union (size, or rather count, of the one array plus the count of the other).