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annotate toolboxes/FullBNT-1.0.7/bnt/CPDs/@tabular_CPD/Old/sample_node_single_case.m @ 0:e9a9cd732c1e tip

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first hg version after svn
author wolffd
date Tue, 10 Feb 2015 15:05:51 +0000
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wolffd@0 1 function y = sample_node(CPD, pev)
wolffd@0 2 % SAMPLE_NODE Draw a random sample from P(Xi | x(pi_i), theta_i) (tabular)
wolffd@0 3 % y = sample_node(CPD, pev)
wolffd@0 4 %
wolffd@0 5 % pev{i} is the value of the i'th parent (if any)
wolffd@0 6
wolffd@0 7 %assert(~any(isemptycell(pev)));
wolffd@0 8
wolffd@0 9 %CPT = CPD_to_CPT(CPD);
wolffd@0 10 %sz = mysize(CPT);
wolffd@0 11 sz = CPD.sizes;
wolffd@0 12 nparents = length(sz)-1;
wolffd@0 13 if nparents > 0
wolffd@0 14 pvals = cat(1, pev{:});
wolffd@0 15 end
wolffd@0 16 switch nparents
wolffd@0 17 case 0, T = CPD.CPT;
wolffd@0 18 case 1, T = CPD.CPT(pvals(1), :);
wolffd@0 19 case 2, T = CPD.CPT(pvals(1), pvals(2), :);
wolffd@0 20 case 3, T = CPD.CPT(pvals(1), pvals(2), pvals(3), :);
wolffd@0 21 case 4, T = CPD.CPT(pvals(1), pvals(2), pvals(3), pvals(4), :);
wolffd@0 22 otherwise,
wolffd@0 23 psz = sz(1:end-1);
wolffd@0 24 ssz = sz(end);
wolffd@0 25 i = subv2ind(psz, pvals(:)');
wolffd@0 26 T = reshape(CPD.CPT, [prod(psz) ssz]);
wolffd@0 27 T = T(i,:);
wolffd@0 28 end
wolffd@0 29
wolffd@0 30 if sz(end)==2
wolffd@0 31 r = rand(1,1);
wolffd@0 32 if r > T(1)
wolffd@0 33 y = 2;
wolffd@0 34 else
wolffd@0 35 y = 1;
wolffd@0 36 end
wolffd@0 37 else
wolffd@0 38 y = sample_discrete(T);
wolffd@0 39 end