CODEWITHSUNDEEP
c#arrayssearch
Pavel T
Pavel T

Reputation: 21

C# - Searching for sequences in arrays

I have some arrays filled with 1 and 0. Is there any easy way to find, for example, 10 fields next to each other with value 1?

Something like: if (array[i ... i+10] = 1) -> do some stuff?

I know that I can use for to do it, but I have a huge multiple array and this will by very helpful.

Upvotes: 1

Views: 1208

Answers (2)

p.s.w.g
p.s.w.g

Reputation: 149068

You can do this pretty easily with a for loop:

int c = 0;
for (int i = 0; i < myArray.Length; i++)
{
    c = (myArray[i] == 1) ? c + 1 : 0;
    if (c >= 10)
    {
        // do stuff
    }
}

Here's another way using Linq:

var indexes =
    from i in Enumerable.Range(0, myArray.Length - 10)
    where myArray.Skip(i).Take(10).All(x => x == 1)
    select i;
foreach(var i in indexes)
{
    // do stuff
}

This will return all indexes of myArray where the element at that index and the elements next 9 indexes are all equal to 1. However, this method is somewhat less efficient than the simple for-loop because it potentially checks each item more than once.

If you prefer fluent syntax:

var indexes = Enumerable.Range(0, myArray.Length - 10)
                        .Where(i => myArray.Skip(i).Take(10).All(x => x == 1));
foreach(var i in indexes)
{
    // do stuff
}

Upvotes: 7

Mare Infinitus
Mare Infinitus

Reputation: 8192

If I understand your question right, you want to do something called pattern matching.

There are many algorithms out there. A first starting point is this page here

From the algorithms the Turbo-Boyer-Moore is one that is performing best.

But you can also handle that problem with a data structure, like a suffix tree: see this article on suffix trees (or simply called Trie)

Here is an implementation of the Boyer-Moore algorithm Codeproject article on Boyer-Moore

Upvotes: 1

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