Mercurial > hg > camir-aes2014
view toolboxes/FullBNT-1.0.7/bnt/CPDs/@noisyor_CPD/noisyor_CPD.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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function CPD = noisyor_CPD(bnet, self, leak_inhibit, inhibit) % NOISYOR_CPD Make a noisy-or CPD % CPD = NOISYOR_CPD(BNET, NODE_NUM, LEAK_INHIBIT, INHIBIT) % % A noisy-or node turns on if any of its parents are on, provided they are not inhibited. % The prob. that the i'th parent gets inhibited (flipped from 1 to 0) is inhibit(i). % The prob that the leak node (a dummy parent that is always on) gets inhibit is leak_inhibit. % These params default to random values if omitted. % % Example: suppose C has parents A and B, and the % link of A->C fails with prob pA and the link B->C fails with pB. % Then the noisy-OR gate defines the following distribution % % A B P(C=0) % 0 0 1.0 % 1 0 pA % 0 1 pB % 1 1 pA * PB % % Currently, learning is not supported for noisy-or nodes % (since the M step is somewhat complicated). % % For simple generalizations of the noisy-OR model, see e.g., % - Srinivas, "A generalization of the noisy-OR model", UAI 93 % - Meek and Heckerman, "Learning Causal interaction models", UAI 97. if nargin==0 % This occurs if we are trying to load an object from a file. CPD = init_fields; CPD = class(CPD, 'noisyor_CPD', discrete_CPD(1, [])); return; elseif isa(bnet, 'noisyor_CPD') % This might occur if we are copying an object. CPD = bnet; return; end CPD = init_fields; ps = parents(bnet.dag, self); fam = [ps self]; ns = bnet.node_sizes; assert(all(ns(fam)==2)); assert(isempty(myintersect(fam, bnet.cnodes))); if nargin < 3, leak_inhibit = rand(1, 1); end if nargin < 4, inhibit = rand(1, length(ps)); end CPD.self = self; CPD.inhibit = inhibit; CPD.leak_inhibit = leak_inhibit; % For BIC CPD.nparams = 0; CPD.nsamples = 0; CPD.CPT = []; % cached copy, to speed up CPD_to_CPT clamped = 1; CPD = class(CPD, 'noisyor_CPD', discrete_CPD(clamped, ns([ps self]))); %%%%%%%%%%% function CPD = init_fields() % This ensures we define the fields in the same order % no matter whether we load an object from a file, % or create it from scratch. (Matlab requires this.) CPD.self = []; CPD.inhibit = []; CPD.leak_inhibit = []; CPD.nparams = []; CPD.nsamples = []; CPD.CPT = [];