Mercurial > hg > camir-aes2014
diff toolboxes/FullBNT-1.0.7/bnt/CPDs/@tabular_CPD/Old/sample_node.m @ 0:e9a9cd732c1e tip
first hg version after svn
author | wolffd |
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date | Tue, 10 Feb 2015 15:05:51 +0000 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/toolboxes/FullBNT-1.0.7/bnt/CPDs/@tabular_CPD/Old/sample_node.m Tue Feb 10 15:05:51 2015 +0000 @@ -0,0 +1,53 @@ +function y = sample_node(CPD, pev, nsamples) +% SAMPLE_NODE Draw a random sample from P(Xi | x(pi_i), theta_i) (tabular) +% Y = SAMPLE_NODE(CPD, PEV, NSAMPLES) +% +% pev(i,m) is the value of the i'th parent in sample m (if there are any parents). +% y(m) is the m'th sampled value (a row vector). +% (If pev is a cell array, so is y.) +% nsamples defaults to 1. + +if nargin < 3, nsamples = 1; end + +%if nargin < 4, usecell = 0; end +if iscell(pev), usecell = 1; else usecell = 0; end + +if nsamples == 1, pev = pev(:); end + +sz = CPD.sizes; +nparents = length(sz)-1; +if nparents==0 + y = sample_discrete(CPD.CPT, 1, nsamples); + if usecell + y = num2cell(y); + end + return; +end + +sz = CPD.sizes; +[nparents nsamples] = size(pev); + +if usecell + pvals = cell2num(pev)'; % each row is a case +else + pvals = pev'; +end + +psz = sz(1:end-1); +ssz = sz(end); +ndx = subv2ind(psz, pvals); +T = reshape(CPD.CPT, [prod(psz) ssz]); +T2 = T(ndx,:); % each row is a distribution selected by the parents +C = cumsum(T2, 2); % sum across columns +R = rand(nsamples, 1); +y = ones(nsamples, 1); +for i=1:ssz-1 + y = y + (R > C(:,i)); +end +y = y(:)'; +if usecell + y = num2cell(y); +end + + +