comparison toolboxes/FullBNT-1.0.7/bnt/CPDs/@noisyor_CPD/noisyor_CPD.m @ 0:e9a9cd732c1e tip

first hg version after svn

+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 = [];