gdlCluster.m

function clusteredLabels = gdlCluster (distance_matrix, groupNumber, K, a, usingKcCluster, p)
%% Graph Agglomerative Clustering toolbox
% Input: 
%   - distance_matrix: pairwise distances, d_{i -> j}
%   - groupNumber: the final number of clusters
%   - strDescr: structural descriptor. The choice can be
%                 - 'gdl': graph degree linkage algorithm
%                 - others to be added
%   - K: the number of nearest neighbors for KNN graph, default: 20
%   - p: merging (p+1)-links in l-links algorithm, default: 1
%   - a: for covariance estimation, default: 1 
%       sigma^2 = (\sum_{i=1}^n \sum_{j \in N_i^3} d_{ij}^2) * a
% Output:
%   - clusteredLabels: clustering results
% by Wei Zhang (wzhang009 at gmail.com), June, 8, 2011
%
% Please cite the following papers, if you find the code is helpful
%
% W. Zhang, X. Wang, D. Zhao, and X. Tang. 
% Graph Degree Linkage: Agglomerative Clustering on a Directed Graph.
% in Proceedings of European Conference on Computer Vision (ECCV), 2012.
% 
% W. Zhang, D. Zhao, and X. Wang. 
% Agglomerative clustering via maximum incremental path integral.
% Pattern Recognition, 46 (11): 3056-3065, 2013.

%% parse inputs
disp('--------------- Graph Agglomerative Clustering ---------------------');

if nargin < 2, error('GAC: input arguments are not enough!'); end
if nargin < 3, K = 20;   end
if nargin < 4, a = 1; end
if nargin < 5, usingKcCluster = true; end
if nargin < 6, p = 1;    end

%% initialization
    disp('---------- Building graph and forming initial clusters with l-links ---------');
    [graphW, NNIndex] = gacBuildDigraph_c(distance_matrix, K, a);
    initialClusters = gacBuildLlinks_cwarpper(distance_matrix, p, NNIndex);
    clear distance_matrix NNIndex

    disp('-------------------------- Zeta merging --------------------------');
        if usingKcCluster
            clusteredLabels = gdlMergingKNN_c(graphW, initialClusters, groupNumber);
        else
            clusteredLabels = gdlMerging_c(graphW, initialClusters, groupNumber);
        end

end