Are there any Fuzzy Search or String Similarity Functions libraries written for C#?

Question

There are similar question, but not regarding C# libraries I can use in my source code.

Thank you all for your help.

I've already saw lucene, but I need something more easy to search for similar strings and without the overhead of the indexing part.

The answer I marked has got two very easy algorithms, and one uses LINQ too, so it's perfect.

Solution 1

Levenshtein distance implementation:

• Using LINQ (not really, see comments)
• Not using LINQ

I have a .NET 1.1 project in which I use the latter. It's simplistic, but works perfectly for what I need. From what I remember it needed a bit of tweaking, but nothing that wasn't obvious.

Solution 2

you can also look at the very impressive library titled Sam's String Metrics https://github.com/StefH/SimMetrics.Net . this includes a host of algorithms.

• Hamming distance
• Levenshtein distance
• Needleman-Wunch distance or Sellers Algorithm
• Smith-Waterman distance
• Gotoh Distance or Smith-Waterman-Gotoh distance
• Block distance or L1 distance or City block distance
• Monge Elkan distance
• Jaro distance metric
• Jaro Winkler
• SoundEx distance metric
• Matching Coefficient
• Dice’s Coefficient
• Jaccard Similarity or Jaccard Coefficient or Tanimoto coefficient
• Overlap Coefficient
• Euclidean distance or L2 distance
• Cosine similarity
• Variational distance
• Hellinger distance or Bhattacharyya distance
• Information Radius (Jensen-Shannon divergence)
• Harmonic Mean
• Skew divergence
• Confusion Probability
• Tau
• Fellegi and Sunters (SFS) metric
• TFIDF or TF/IDF
• FastA
• BlastP
• Maximal matches
• q-gram
• Ukkonen Algorithms

Solution 3

They are not my own invention, but they are my favorites and I've just blogged about them and published my own tweaked versions of Dice Coefficient, Levenshtein Distance, Longest Common Subsequence and Double Metaphone in a blog post called Four Functions for Finding Fuzzy String Matches in C# Extensions.

Solution 4

Have you taken a look at Lucene.net? It is a port of the Java Lucene search engine API to the .Net platform. That library offers a lot of search functionality. I played around with it a year or so ago, so don't take my suggestion as based on tons of experience. I saw it in the book Windows Developer Power Tools and took it for a test drive. You might look through their API documentation to see if it offers something like the Fuzzy Search for which you are looking.

Solution 5

There is the following Levenshtein Distance Algorithm which assigns a value to the similarity of two strings (well, the difference actually), that could be used to build upon: http://www.merriampark.com/ldcsharp.htm

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Comments

[Thomas Levesque]

Why do you say "Using LINQ" ? None of these implementations uses Linq...

[Abhishek]

Indeed you are correct. I could have sworn that there was some LINQ-love in it, or at least that the headline claimed it was LINQy or something.

[Eugeniu Torica]

Could you please tell how to get the degree of similarity using Lucene?

[Jason Jackson]

Sorry, I have not used it professionally. As I mentioned in my post, I just played around with it probably around 2007/2008.

[Hamish Grubijan]

What if I have 100,000 entries to search, and I want to show the top 20 candidates each time?

[Paul Ruane]

The link in this answer is giving me a 403 error. You can use the Wayback Machine instead.

[Roman]

Dead link may now be here dotnetperls.com/levenshtein

[dalenewman]

I believe the .NET version of the library mentioned above is here. After I converted it to Visual Studio 2010, and updated NUnit references, it builds. It also passes 87 tests.

[cjbarth]

These are ready-made in a class that you can just drop into your project. This is the easy man's way to go.

[AechoLiu]

Maybe the book Lucene in Action, 2ed could tell how to get the degree of similarity.

[Maneesh Babu M]

code now on GitHub github.com/tylerjensen/duovia-fuzzystrings

[Good Night Nerd Pride]

Updated link to the blog post: tsjensen.com/blog/post/2011/05/27/…

[Spiralis]

I found a .net library version of this library on SimMetrics.Net on GitHub. The same as the suggestion from @dalenewman, just on github perhaps?