findClosestCentriods.m

function idx = findClosestCentroids(X, centroids)

% Set K
K = size(centroids, 1);

% Set empty indices vector 
idx = zeros(size(X,1), 1);

% for every example in X...
for i = 1:size(X, 1)

    % get the row
    row = X(i, :);
    
    % initialize a minimum distance value as infinite so every distance is smaller
    min_dist = Inf;

    % for every centriod...
    for j = 1:size(centroids, 1)
    
        % get the centriod row
        centriod_row = centroids(j, :);
        
        % calculate distance and if smaller, 
        %   1. update the idx vector with the centriod index
        %   2. update the min distance to the distance
        distance = sum((row - centriod_row).^2);
        if distance < min_dist
            idx(i) = j;
            min_dist = distance;
        end
    end
end

end