comparison toolboxes/FullBNT-1.0.7/bnt/inference/dynamic/@hmm_inf_engine/enter_evidence.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function [engine, loglik] = enter_evidence(engine, evidence, varargin)
+% ENTER_EVIDENCE Add the specified evidence to the network (hmm)
+% [engine, loglik] = enter_evidence(engine, evidence, ...)
+%
+% evidence{i,t} = [] if if X(i,t) is hidden, and otherwise contains its observed value (scalar or column vector)
+%
+% The following optional arguments can be specified in the form of name/value pairs:
+% [default value in brackets]
+%
+% maximize - if 1, does max-product (not yet supported), else sum-product [0]
+% filter   - if 1, does filtering, else smoothing [0]
+% oneslice - 1 means only compute marginals on nodes within a single slice [0]
+%
+% e.g., engine = enter_evidence(engine, ev, 'maximize', 1)
+
+maximize = 0;
+filter = 0;
+oneslice = 0;
+
+% parse optional params
+args = varargin;
+nargs = length(args);
+if nargs > 0
+  for i=1:2:nargs
+    switch args{i},
+     case 'maximize', maximize = args{i+1}; 
+     case 'filter',  filter = args{i+1}; 
+     case 'oneslice', oneslice = args{i+1};
+     otherwise,  
+      error(['invalid argument name ' args{i}]);       
+    end
+  end
+end
+
+[ss T] = size(evidence);
+engine.maximize = maximize;
+engine.evidence = evidence;
+bnet = bnet_from_engine(engine);
+engine.node_sizes = repmat(bnet.node_sizes_slice(:), [1 T]);
+
+obs_bitv = ~isemptycell(evidence(:));
+bitv = reshape(obs_bitv, ss, T);
+for t=1:T
+  onodes = find(bitv(:,t));
+  if ~isequal(onodes, bnet.observed(:))
+    error(['dbn was created assuming observed nodes per slice were '...
+	   num2str(bnet.observed(:)')  ' but the evidence in slice ' num2str(t) ...
+	   ' has observed nodes ' num2str(onodes(:)')]);
+  end
+end
+
+obslik = mk_hmm_obs_lik_matrix(engine, evidence);
+
+%[alpha, beta, gamma, loglik, xi] = fwdback(engine.startprob, engine.transprob, obslik, ...
+[alpha, beta, gamma, loglik, xi] = fwdback_twoslice(engine, engine.startprob,...
+                                                    engine.transprob, obslik, ...
+                                                    'maximize', maximize, 'fwd_only', filter, ...
+                                                    'compute_xi', ~oneslice);
+
+engine.one_slice_marginal = gamma; % gamma(:,t) for t=1:T
+if ~oneslice
+  Q = size(gamma,1);
+  engine.two_slice_marginal = reshape(xi, [Q*Q T-1]); % xi(:,t) for t=1:T-1
+end