by Leo Creates an ensemble of cart trees similar to the matlab TreeBagger class.
function f_hist = weighted_hist(fdata,weights,nlabels)
%WEIGHTED_HIST Computes weighted histograms
% f_hist = weighted_hist(fdata,weights,nlabels);
% fdata is a 2-D matrix MxN where M is the number of votes and N the
% number of samples.
% weights is a Mx1 weight vector
% nlabels is the number of labels
v_subs = fdata + nlabels*repmat(0:(size(fdata,2)-1),size(fdata,1),1);
weights_val = repmat(weights,1,size(v_subs,2));
f_hist = accumarray(v_subs(:),weights_val(:));
f_hist = reshape(f_hist,nlabels,size(fdata,2));