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

first hg version after svn

+function CPD = gmux_CPD(bnet, self, varargin)
+% GMUX_CPD Make a Gaussian multiplexer node
+%
+% CPD = gmux_CPD(bnet, node, ...) is used similarly to gaussian_CPD,
+% except we assume there is exactly one discrete parent (call it M)
+% which is used to select which cts parent to pass through to the output.
+% i.e., we define P(Y=y|M=m, X1, ..., XK) = N(y | W(m)*x(m) + mu(m), Sigma(m))
+% where Y represents this node, and the Xi's are the cts parents.
+% All the Xi must have the same size, and the num values for M must be K.
+%
+% Currently the params for this kind of CPD cannot be learned.
+%
+% Optional arguments [ default in brackets ]
+%
+% mean       - mu(:,i) is the mean given M=i [ zeros(Y,K) ]
+% cov        - Sigma(:,:,i) is the covariance given M=i [ repmat(1*eye(Y,Y), [1 1 K]) ]
+% weights    - W(:,:,i) is the regression matrix given M=i [ randn(Y,X,K) ]
+
+if nargin==0
+  % This occurs if we are trying to load an object from a file.
+  CPD = init_fields;
+  clamp = 0;
+  CPD = class(CPD, 'gmux_CPD', generic_CPD(clamp));
+  return;
+elseif isa(bnet, 'gmux_CPD')
+  % This might occur if we are copying an object.
+  CPD = bnet;
+  return;
+end
+CPD = init_fields;
+ 
+CPD = class(CPD, 'gmux_CPD', generic_CPD(1));
+
+ns = bnet.node_sizes;
+ps = parents(bnet.dag, self);
+dps = myintersect(ps, bnet.dnodes);
+cps = myintersect(ps, bnet.cnodes);
+fam_sz = ns([ps self]);
+
+CPD.self = self;
+CPD.sizes = fam_sz;
+
+% Figure out which (if any) of the parents are discrete, and which cts, and how big they are
+% dps = discrete parents, cps = cts parents
+CPD.cps = find_equiv_posns(cps, ps); % cts parent index
+CPD.dps = find_equiv_posns(dps, ps);
+if length(CPD.dps) ~= 1
+  error('gmux must have exactly 1 discrete parent')
+end
+ss = fam_sz(end);
+cpsz = fam_sz(CPD.cps(1)); % in gaussian_CPD, cpsz = sum(fam_sz(CPD.cps))
+if ~all(fam_sz(CPD.cps) == cpsz)
+  error('all cts parents must have same size')
+end
+dpsz = fam_sz(CPD.dps);
+if dpsz ~= length(cps)
+  error(['the arity of the mux node is ' num2str(dpsz) ...
+	 ' but there are ' num2str(length(cps)) ' cts parents']);
+end
+
+% set default params
+%CPD.mean = zeros(ss, 1);
+%CPD.cov = eye(ss);
+%CPD.weights = randn(ss, cpsz);
+CPD.mean = zeros(ss, dpsz);
+CPD.cov = 1*repmat(eye(ss), [1 1 dpsz]);    
+CPD.weights = randn(ss, cpsz, dpsz);
+
+args = varargin;
+nargs = length(args);
+for i=1:2:nargs
+  switch args{i},
+   case 'mean',        CPD.mean = args{i+1}; 
+   case 'cov',         CPD.cov = args{i+1}; 
+   case 'weights',    CPD.weights = args{i+1}; 
+   otherwise,  
+    error(['invalid argument name ' args{i}]);
+  end
+end
+
+%%%%%%%%%%%
+
+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.sizes = [];
+CPD.cps = [];
+CPD.dps = [];
+CPD.mean = [];
+CPD.cov = [];
+CPD.weights = [];
+