Grouping neighbouring entries with the same value in a 2d array

Question

EDIT: I now realized the question was not appropriate for stack but I've gotten a lot of helpful advice anyway. Thanks everyone!

I have a 2d array and I want to group together neighbors of the same value. Using C# (working with unity).

Let's say I have this:

int[,] array {   
    0,0,0,0,0,0,1,0,0,0,  
    0,1,1,0,0,0,1,0,0,0,  
    0,1,0,0,0,0,0,0,0,0,  
    0,0,0,0,0,0,1,1,1,0,  
    0,0,0,0,0,0,1,1,1,0  
}

There are three "clusters" of 1:s. I want to add them to a dictionary with some variable for identification. So maybe first add the neighboring values to a list, add that list to a dictionary, clear the list and move onto the next cluster.

The columns and rows would be of equal length in the real thing.

I would also want the sorting method to accept arrays of various sizes so no hardcoded values. I parse the array from an XML document.

I've tried looking into Array.Sort but the resources I have found have been exclusively about sorting values in as/descending order. Just pointing me in the right direction, some some relevant web resources would be greatly appreciated!

Answer 1

I'm not going to give you the answer in full code since 1. you shouldn't be asking for it here and 2. you can definitely work it out yourself.

This is a good opportunity for you to whip out your pen and paper and figure out the algorithm. Lets say we want something similar to your task: just grouping the clusters of ones. The pseudocode might look like this.

1. Create a list of clusters
2. For each element in the grid, check if its a one.
3. If it is a one, check if it has a neighbor that is part of a cluster. If so, add it to that cluster, else create a new cluster an add it.

If would then run through this on paper with a small example.

Once you have your desired algorithm, putting it into a dictionary and sorting it should be trivial.