CODEWITHSUNDEEP
c#linq
Santino
Santino

Reputation: 815

Create a list from pairwise comparison

I perform a pairwise comparison on a number of objects and estimate the similarity

Item-1,Item-2,Similarity
11, 16, 0.9
11, 18, 0.5
11, 21, 0.9
12, 19, 0.8
12,22, 0.9
12, 24, 0.3

I wish to now create clusters based on a threshold, for example with a threshold of 0.8 would like to create lists as below:

{11,16, 21}
{12,19,22} 

with threshold > 0.8

Is there a way to do this in LINQ? I found several ways of generating pairs from lists, however I need to do it in reverse.

Upvotes: 0

Views: 540

Answers (2)

tvanfosson
tvanfosson

Reputation: 532435

Assuming you have a collection of such pairs with the properties, Item1, Item2, and Similarity where the first two are integers and the second a double.

var threshold = 0.8f;
var sets = pairs.Where(p => p.Similarity > threshold)
                .GroupBy(p => p.Item1, p => p.Item2)
                .Select(g => new [] { g.Key }.Union(g));

Upvotes: 2

Kyle W
Kyle W

Reputation: 3752

You can get the requested groups using

items.Where(i => i.Similarity >= .8).GroupBy(i => i.Item1)

and then the list is group.Key + group.Select(i => i.Item2)

Upvotes: 1

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