Mercurial > hg > camir-aes2014
comparison toolboxes/FullBNT-1.0.7/bnt/inference/static/@belprop_fg_inf_engine/find_mpe.m @ 0:e9a9cd732c1e tip
first hg version after svn
author | wolffd |
---|---|
date | Tue, 10 Feb 2015 15:05:51 +0000 |
parents | |
children |
comparison
equal
deleted
inserted
replaced
-1:000000000000 | 0:e9a9cd732c1e |
---|---|
1 function mpe = find_mpe(engine, evidence, varargin) | |
2 % FIND_MPE Find the most probable explanation of the data (belprop_fg) | |
3 % function mpe = find_mpe(engine, evidence,...) | |
4 % | |
5 % evidence{i} = [] if X(i) is hidden, and otherwise contains its observed value (scalar or column vector). | |
6 % | |
7 % This finds the marginally most likely value for each hidden node, | |
8 % and may give the wrong results even if the graph is acyclic, | |
9 % unless you set break_ties = 1. | |
10 % | |
11 % The following optional arguments can be specified in the form of name/value pairs: | |
12 % [default value in brackets] | |
13 % | |
14 % break_ties is optional. If 1, we will force ties to be broken consistently | |
15 % by calling enter_evidence N times. (see Jensen96, p106) Default = 1. | |
16 | |
17 break_ties = 1; | |
18 | |
19 % parse optional params | |
20 args = varargin; | |
21 nargs = length(args); | |
22 for i=1:2:nargs | |
23 switch args{i}, | |
24 case 'break_ties', break_ties = args{i+1}; | |
25 otherwise, | |
26 error(['invalid argument name ' args{i}]); | |
27 end | |
28 end | |
29 | |
30 engine = enter_evidence(engine, evidence, 'maximize', 1); | |
31 | |
32 observed = ~isemptycell(evidence); | |
33 evidence = evidence(:); % hack to handle unrolled DBNs | |
34 N = length(evidence); | |
35 mpe = cell(1,N); | |
36 for i=1:N | |
37 m = marginal_nodes(engine, i); | |
38 % observed nodes are all set to 1 inside the inference engine, so we must undo this | |
39 if observed(i) | |
40 mpe{i} = evidence{i}; | |
41 else | |
42 mpe{i} = argmax(m.T); | |
43 if break_ties | |
44 evidence{i} = mpe{i}; | |
45 [engine, ll] = enter_evidence(engine, evidence, 'maximize', 1); | |
46 end | |
47 end | |
48 end | |
49 |