diff options
Diffstat (limited to 'sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine')
6 files changed, 123 insertions, 0 deletions
diff --git a/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/CVS/Entries b/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/CVS/Entries new file mode 100644 index 00000000..c9482cbd --- /dev/null +++ b/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/CVS/Entries @@ -0,0 +1,4 @@ +/enter_evidence.m/1.1.1.1/Wed May 29 15:59:56 2002// +/likelihood_weighting_inf_engine.m/1.1.1.1/Wed May 29 15:59:56 2002// +/marginal_nodes.m/1.1.1.1/Wed May 29 15:59:56 2002// +D diff --git a/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/CVS/Repository b/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/CVS/Repository new file mode 100644 index 00000000..e39429d7 --- /dev/null +++ b/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/CVS/Repository @@ -0,0 +1 @@ +FullBNT/BNT/inference/static/@likelihood_weighting_inf_engine diff --git a/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/CVS/Root b/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/CVS/Root new file mode 100644 index 00000000..f3bd14a6 --- /dev/null +++ b/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/CVS/Root @@ -0,0 +1 @@ +:ext:nsaunier@bnt.cvs.sourceforge.net:/cvsroot/bnt diff --git a/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/enter_evidence.m b/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/enter_evidence.m new file mode 100644 index 00000000..62e252aa --- /dev/null +++ b/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/enter_evidence.m @@ -0,0 +1,39 @@ +function [engine, ll] = enter_evidence(engine, evidence, nsamples) +% ENTER_EVIDENCE Add the specified evidence to the network (likelihood_weighting) +% [engine, ll] = enter_evidence(engine, evidence, nsamples) +% evidence{i} = [] if if X(i) is hidden, and otherwise contains its observed value (scalar or column vector) +% +% If nsamples is not specified, the value specified when the engine was created will be used. +% ll (log-likelihood) is set to []. + +ll = []; +if nargin < 3, nsamples = engine.nsamples; end + +bnet = bnet_from_engine(engine); +N = length(bnet.dag); +samples = cell(nsamples, N); +weights = zeros(1, nsamples); + +ns = bnet.node_sizes; +original_evidence = evidence; +observed = ~isemptycell(original_evidence); +for s=1:nsamples + evidence = original_evidence(:); % must be a column vector + w = 1; + for i=1:N + ps = parents(bnet.dag, i); + e = bnet.equiv_class(i); + if observed(i) + p = exp(log_prob_node(bnet.CPD{e}, evidence(i), evidence(ps))); + w = w * p; + else + x = sample_node(bnet.CPD{e}, evidence(ps)); + evidence{i} = x; + end + end + samples(s,:) = evidence; + weights(s) = w; +end + +engine.samples = samples; +engine.weights = weights; diff --git a/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/likelihood_weighting_inf_engine.m b/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/likelihood_weighting_inf_engine.m new file mode 100644 index 00000000..eb1794fa --- /dev/null +++ b/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/likelihood_weighting_inf_engine.m @@ -0,0 +1,25 @@ +function engine = likelihood_weighting_inf_engine(bnet, varargin) +% LIKELIHOOD_WEIGHTING_INF_ENGINE +% engine = likelihood_weighting_inf_engine(bnet, ...) +% +% Optional arguments [defaults] +% nsamples - [500] + +nsamples = 500; + +if nargin >= 2 + args = varargin; + nargs = length(args); + for i=1:2:nargs + switch args{i}, + case 'nsamples', nsamples= args{i+1}; + otherwise, + error(['invalid argument name ' args{i}]); + end + end +end + +engine.nsamples = nsamples; +engine.samples = []; +engine.weights = []; +engine = class(engine, 'likelihood_weighting_inf_engine', inf_engine(bnet)); diff --git a/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/marginal_nodes.m b/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/marginal_nodes.m new file mode 100644 index 00000000..d00ee606 --- /dev/null +++ b/sourcecodes/bnt-master/BNT/inference/static/@likelihood_weighting_inf_engine/marginal_nodes.m @@ -0,0 +1,53 @@ +function marginal = marginal_nodes(engine, nodes) +% MARGINAL_NODES Compute the marginal on the specified query nodes (likelihood_weighting) +% marginal = marginal_nodes(engine, nodes) + +bnet = bnet_from_engine(engine); +ddom = myintersect(nodes, bnet.dnodes); +cdom = myintersect(nodes, bnet.cnodes); +nsamples = size(engine.samples, 1); +ns = bnet.node_sizes; + +%w = normalise(engine.weights); +w = engine.weights; +if mysubset(nodes, ddom) + T = 0*myones(ns(nodes)); + P = prod(ns(nodes)); + indices = ind2subv(ns(nodes), 1:P); + samples = reshape(cat(1, engine.samples{:,nodes}), nsamples, length(nodes)); + for j = 1:P + rows = find_rows(samples, indices(j,:)); + T(j) = sum(w(rows)); + end + T = normalise(T); + marginal.T = T; +elseif subset(nodes, cdom) + samples = reshape(cat(1, engine.samples{:,nodes}), nsamples*sum(ns(nodes)), length(nodes)); + [marginal.mu, marginal.Sigma] = wstats(samples', normalise(w)); +else + error('can''t handle mixed marginals yet'); +end + +marginal.domain = nodes; + +%%%%%%%%% + +function rows = find_rows(M, v) +% FINDROWS Find rows which are equal to a specified vector +% rows = findrows(M, v) +% Each row of M is a sample + +temp = abs(M - repmat(v, size(M, 1), 1)); +rows = find(sum(temp,2) == 0); + +%%%%%%%% + +function [mu, Sigma] = wstats(X, w) + +% Computes the weighted mean and weighted covariance matrix for a given +% set of observations X(:,i), and a set of normalised weights w(i). +% Each column of X is a sample. + +d = X - repmat(X * w', 1, size(X, 2)); +mu = sum(X .* repmat(w, size(X, 1), 1), 2); +Sigma = d * diag(w) * d'; |