C# - Fuzzy compare of two large string arrays

问题

I need to find all strings in B that "partly" exists in A.

B = [ "Hello World!", "Hello Stack Overflow!", "Foo Bar!", "Food is nice...", "Hej" ]
A = [ "World", "Foo" ]
C = B.FuzzyCompare(A) // C = [ "Hello World!", "Foo Bar!", "Food is nice..." ]

I've been looking into using Levenshtein Distance Algorithm for the "fuzzy" part of the problem, as well as LINQ for the iterations. However, A * B usually results in over 1,5 billion comparisons.

How should i go about this? Is there a way to quickly "almost compare" two Lists of strings?

回答1:

Maybe it's sufficient to simply compare substrings, this would be much more efficient:

var C = B.Where(s1 => A.Any(s2 => s1.IndexOf(s2, StringComparison.OrdinalIgnoreCase) >= 0)).ToList();

回答2:

This seems like a good use of a Suffix Trie.

A Suffix Trie is a tree with no payload. It indexes all suffixes of a given string or sentence so that they can be searched in O(n) time. So, if your input in A was "hello", it would index "hello", "ello", "llo", "lo", and "o" in a way that would allow any of those substrings to immediately and efficiently be looked up without any additional enumeration of the set of A.

Basically, take all the values in A and process them into a Suffix Trie which is an O(n * m) operation done once where n is the number of elements in A and m is the length of the elements. Then for each element of B check for it in the Suffix Trie which is also an O(n * m) operation where n is the number of elements in B and m is the length of the elements.

回答3:

I think you may be other thinking it:

List<string> results = new List<string>();
foreach (string test in B)
{
   if (A.Any(a => test.Contains(a))
      results.Add(test);
}

BTW the complexity of this is somewhere in the region of O(n)(best) and O(n*m)(worst) (where n is the numer of results in A and m is the number of results in B)

来源：https://stackoverflow.com/questions/38332395/c-sharp-fuzzy-compare-of-two-large-string-arrays

标签

string

linq

loops

compare