frontier_fast_inf_engine.m

来自「Bayes网络工具箱」· M 代码 · 共 92 行

function engine = frontier_fast_inf_engine(bnet, onodes)
% FRONTIER_FAST_INF_ENGINE Inference engine for DBNs which which uses the frontier algorithm, with optimizations
% engine = frontier_fast_inf_engine(bnet, onodes)
%
% This is just like frontier_inf_engine, except the 'onodes' argument is required.
% The observed nodes in every slice must be equal to onodes.
% All hidden nodes must be discrete.

pengine = frontier_inf_engine(bnet, onodes);
fengine = struct(pengine); % violate object privacy
engine.onodes = onodes;

ns = bnet.node_sizes(:)';
ss = length(bnet.intra);
onodes2 = unroll_set(onodes(:), ss, 2);
ns(onodes2(:)') = 1;

[engine.fndx, engine.CPD_ndx] = mk_indices(fengine.fdom, 2, ns, fengine.ops, bnet.dag);
[engine.fndx1, engine.CPD_ndx1] = mk_indices(fengine.fdom1, 1, ns, fengine.ops1, bnet.dag);
  
[engine.rev_fndx, engine.rev_CPD_ndx] = mk_rev_indices(fengine.fdom, 2, ns, -fengine.ops,  bnet.dag);
[engine.rev_fndx1, engine.rev_CPD_ndx1] = mk_rev_indices(fengine.fdom1, 1, ns, -fengine.ops1, bnet.dag);

engine = class(engine, 'frontier_fast_inf_engine', pengine);


%%%%%%%%%
function [fndx, CPD_ndx] = mk_rev_indices(fdom, t, ns, ops, dag)

ss = length(ns)/2;
if t==1
  S = ss;
else
  S = 2*ss;
end
mult_ndx = cell(1,S);
marg_ndx = cell(1,S);
CPD_ndx = cell(1,S);
for s=S:-1:1
  olddom = fdom{s};
  if s==1
    if t==1
      newdom = [];
    else
      newdom = 1:ss;
    end
  else
    newdom = fdom{s-1};
  end
  i = ops(s);
  if i>0
    fndx{s} = mk_multiply_table_ndx(newdom, olddom, ns);
  else
    fam = family(dag, -i);
    CPD_ndx{s} = mk_multiply_table_ndx(olddom, fam, ns);
    assert(isequal(newdom, mysetdiff(olddom, -i)));
    fndx{s} = mk_marginalise_table_ndx(olddom, newdom, ns);
  end
end


%%%%%%%%%
function [fndx, CPDndx] = mk_indices(fdom, t, ns, ops, dag)

ss = length(ns)/2;
if t==1
  S = ss;
else
  S = 2*ss;
end
fndx = cell(1,S);
CPDndx = cell(1,S);
for s=1:S
  i = ops(s);
  newdom = fdom{s};
  if s==1
    if t==2
      olddom = 1:ss;
    else
      olddom = [];
    end
  else
    olddom = fdom{s-1};
  end
  if i>0
    fndx{s} = mk_multiply_table_ndx(newdom, olddom, ns);
    CPDndx{s} = mk_multiply_table_ndx(newdom, family(dag, i), ns);
  else
    fndx{s} = mk_marginalise_table_ndx(olddom, newdom, ns);
  end
end