Mercurial > hg > camir-aes2014
annotate toolboxes/FullBNT-1.0.7/bnt/CPDs/@tabular_CPD/Old/sample_node.m @ 0:e9a9cd732c1e tip
first hg version after svn
| author | wolffd |
|---|---|
| date | Tue, 10 Feb 2015 15:05:51 +0000 |
| parents | |
| children |
| rev | line source |
|---|---|
| wolffd@0 | 1 function y = sample_node(CPD, pev, nsamples) |
| 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, NSAMPLES) |
| wolffd@0 | 4 % |
| wolffd@0 | 5 % pev(i,m) is the value of the i'th parent in sample m (if there are any parents). |
| wolffd@0 | 6 % y(m) is the m'th sampled value (a row vector). |
| wolffd@0 | 7 % (If pev is a cell array, so is y.) |
| wolffd@0 | 8 % nsamples defaults to 1. |
| wolffd@0 | 9 |
| wolffd@0 | 10 if nargin < 3, nsamples = 1; end |
| wolffd@0 | 11 |
| wolffd@0 | 12 %if nargin < 4, usecell = 0; end |
| wolffd@0 | 13 if iscell(pev), usecell = 1; else usecell = 0; end |
| wolffd@0 | 14 |
| wolffd@0 | 15 if nsamples == 1, pev = pev(:); end |
| wolffd@0 | 16 |
| wolffd@0 | 17 sz = CPD.sizes; |
| wolffd@0 | 18 nparents = length(sz)-1; |
| wolffd@0 | 19 if nparents==0 |
| wolffd@0 | 20 y = sample_discrete(CPD.CPT, 1, nsamples); |
| wolffd@0 | 21 if usecell |
| wolffd@0 | 22 y = num2cell(y); |
| wolffd@0 | 23 end |
| wolffd@0 | 24 return; |
| wolffd@0 | 25 end |
| wolffd@0 | 26 |
| wolffd@0 | 27 sz = CPD.sizes; |
| wolffd@0 | 28 [nparents nsamples] = size(pev); |
| wolffd@0 | 29 |
| wolffd@0 | 30 if usecell |
| wolffd@0 | 31 pvals = cell2num(pev)'; % each row is a case |
| wolffd@0 | 32 else |
| wolffd@0 | 33 pvals = pev'; |
| wolffd@0 | 34 end |
| wolffd@0 | 35 |
| wolffd@0 | 36 psz = sz(1:end-1); |
| wolffd@0 | 37 ssz = sz(end); |
| wolffd@0 | 38 ndx = subv2ind(psz, pvals); |
| wolffd@0 | 39 T = reshape(CPD.CPT, [prod(psz) ssz]); |
| wolffd@0 | 40 T2 = T(ndx,:); % each row is a distribution selected by the parents |
| wolffd@0 | 41 C = cumsum(T2, 2); % sum across columns |
| wolffd@0 | 42 R = rand(nsamples, 1); |
| wolffd@0 | 43 y = ones(nsamples, 1); |
| wolffd@0 | 44 for i=1:ssz-1 |
| wolffd@0 | 45 y = y + (R > C(:,i)); |
| wolffd@0 | 46 end |
| wolffd@0 | 47 y = y(:)'; |
| wolffd@0 | 48 if usecell |
| wolffd@0 | 49 y = num2cell(y); |
| wolffd@0 | 50 end |
| wolffd@0 | 51 |
| wolffd@0 | 52 |
| wolffd@0 | 53 |