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1 function CPDpot = convert_dbn_CPDs_to_tables1(bnet, evidence)
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2 % CONVERT_DBN_CPDS_TO_TABLES Convert CPDs of (possibly instantiated) DBN nodes to tables
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3 % CPDpot = convert_dbn_CPDs_to_tables(bnet, evidence)
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4 %
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5 % CPDpot{n,t} is a table containing P(n,t|pa(n,t), ev)
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6 % All hidden nodes are assumed to be discrete
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7 % We assume the observed nodes are the same in every slice
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8 %
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9 % Evaluating the conditional likelihood of the evidence can be very slow,
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10 % so we take pains to vectorize where possible, i.e., we try to avoid
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11 % calling convert_to_table
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12
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13 [ss T] = size(evidence);
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14 %obs_bitv = ~isemptycell(evidence(:));
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15 obs_bitv = zeros(1, 2*ss);
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16 obs_bitv(bnet.observed) = 1;
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17 obs_bitv(bnet.observed+ss) = 1;
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18
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19 ns = bnet.node_sizes(:);
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20 CPDpot = cell(ss,T);
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21
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22 for n=1:ss
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23 % slice 1
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24 t = 1;
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25 ps = parents(bnet.dag, n);
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26 e = bnet.equiv_class(n, 1);
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27 if ~any(obs_bitv(ps))
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28 CPDpot{n,t} = convert_CPD_to_table_hidden_ps(bnet.CPD{e}, evidence{n,t});
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29 else
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30 CPDpot{n,t} = convert_to_table(bnet.CPD{e}, [ps n], evidence(:,1));
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31 end
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32
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33 % slices 2..T
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34 debug = 1;
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35 if ~obs_bitv(n)
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36 CPDpot = helper_hidden_child(bnet, evidence, n, CPDpot, obs_bitv, debug);
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37 else
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38 CPDpot = helper_obs_child(bnet, evidence, n, CPDpot, obs_bitv, debug);
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39 end
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40 end
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41
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42 if 0
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43 CPDpot2 = convert_dbn_CPDs_to_tables_slow(bnet, evidence);
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44 for t=1:T
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45 for n=1:ss
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46 if ~approxeq(CPDpot{n,t}, CPDpot2{n,t})
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47 fprintf('CPDpot n=%d, t=%d\n',n,t);
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48 keyboard
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49 end
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50 end
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51 end
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52 end
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53
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54
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55 % special cases: c=child, p=parents, d=discrete, h=hidden, 1=1slice
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56 % if c=h=1 then c=d=1, since hidden nodes must be discrete
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57 % c=h c=d p=h p=d p=1 method
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58 % ---------------------------
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59 % 1 1 1 1 - replicate CPT
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60 % 0 1 1 1 1 dhmm
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61 % 0 0 1 1 1 ghmm
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62 % - 1 - 1 - evaluate CPT on evidence
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63 % other loop
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64
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65 %%%%%%%
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66 function CPDpot = helper_hidden_child(bnet, evidence, n, CPDpot, obs_bitv, debug)
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67
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68 [ss T] = size(evidence);
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69 self = n+ss;
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70 ps = parents(bnet.dag, self);
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71 e = bnet.equiv_class(n, 2);
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72 ns = bnet.node_sizes(:);
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73 if ~any(obs_bitv(ps)) % all parents are hidden (hence discrete)
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74 if debug, fprintf('node %d is hidden, all ps are hidden\n', n); end
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75 if myismember(n, bnet.dnodes)
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76 %CPT = CPD_to_CPT(bnet.CPD{e});
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77 %CPT = reshape(CPT, [prod(ns(ps)) ns(self)]);
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78 CPT = convert_CPD_to_table_hidden_ps(bnet.CPD{e}, []);
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79 CPDpot(n,2:T) = num2cell(repmat(CPT, [1 1 T-1]), [1 2]);
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80 else
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81 error(['hidden cts node disallowed'])
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82 end
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83 else % some parents are observed - slow
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84 if mysubset(ps, bnet.dnodes) % all parents are discrete
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85 % given CPT(p1, p2, p3, p4, c), where p1,p3 are observed
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86 % we create CPT([p2 p4 c], [p1 p3]).
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87 % We then convert all observed p1,p3 into indices ndx
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88 % and return CPT(:, ndx)
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89 CPT = CPD_to_CPT(bnet.CPD{e});
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90 domain = [ps self];
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91 % if dom is [3 7 8] and 3,8 are observed, odom_rel = [1 3], hdom_rel = 2,
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92 % odom = [3 8], hdom = 7
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93 odom_rel = find(obs_bitv(domain));
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94 hdom_rel = find(~obs_bitv(domain));
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95 odom = domain(odom_rel);
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96 hdom = domain(hdom_rel);
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97 CPT = permute(CPT, [hdom_rel odom_rel]);
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98 CPT = reshape(CPT, prod(ns(hdom)), prod(ns(odom)));
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99 parents_in_same_slice = all(ps > ss);
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100 if parents_in_same_slice
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101 if debug, fprintf('node %d is hidden, some ps are obs, all ps discrete, 1 slice\n', n); end
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102 data = cell2num(evidence(odom-ss,2:T)); %data(i,t) = val of i'th obs parent at t+1
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103 else
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104 if debug, fprintf('node %d is hidden, some ps are obs, all ps discrete, 2 slice\n', n); end
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105 data = zeros(length(odom), T-1);
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106 for t=2:T
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107 ev = evidence(:,t-1:t);
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108 data(:,t-1) = cell2num(ev(odom));
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109 end
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110 end
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111 ndx = subv2ind(ns(odom), data'); % ndx(t) encodes data(:,t)
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112 CPDpot(n,2:T) = num2cell(CPT(:, ndx), [1 2]);
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113 else % some parents are cts - v slow
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114 if debug, fprintf('node %d is hidden, some ps are obs, some ps cts\n', n); end
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115 for t=2:T
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116 CPDpot{n,t} = convert_to_table(bnet.CPD{e}, [ps self], evidence(:,t-1:t));
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117 end
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118 end
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119 end
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120
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121 %%%%%%%
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122 function CPDpot = helper_obs_child(bnet, evidence, n, CPDpot, obs_bitv, debug)
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123
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124 [ss T] = size(evidence);
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125 self = n+ss;
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126 ps = parents(bnet.dag, self);
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127 e = bnet.equiv_class(n, 2);
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128 ns = bnet.node_sizes(:);
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129 if ~any(obs_bitv(ps)) % all parents are hidden
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130 parents_in_same_slice = all(ps > ss);
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131 if parents_in_same_slice
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132 if debug, fprintf('node %d is obs, all ps are hidden, 1 slice\n', n); end
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133 ps1 = ps - ss;
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134 if myismember(n, bnet.dnodes)
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135 CPT = CPD_to_CPT(bnet.CPD{e});
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136 CPT = reshape(CPT, [prod(ns(ps)) ns(self)]); % what if no parents?
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137 obslik = eval_pdf_cond_multinomial(cell2num(evidence(n,2:T)), CPT);
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138 CPDpot(n,2:T) = num2cell(obslik, 1);
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139 else
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140 S = struct(bnet.CPD{e});
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141 obslik = eval_pdf_cond_gauss(cell2num(evidence(n,2:T)), S.mean, S.cov);
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142 CPDpot(n,2:T) = num2cell(obslik, 1);
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143 end
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144 else % parents span 2 slices - slow
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145 if debug, fprintf('node %d is obs, all ps are hidden , 2 slice\n', n); end
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146 for t=2:T
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147 CPDpot{n,t} = convert_to_table(bnet.CPD{e}, [ps self], evidence(:,t-1:t));
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148 end
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149 end
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150 else
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151 if isempty(ps) % observed root
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152 if debug, fprintf('node %d is obs, no ps\n', n); end
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153 CPT = CPD_to_CPT(bnet.CPD{e});
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154 data = cell2num(evidence(n,2:T));
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155 CPDpot(n,2:T) = CPT(data);
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156 else % some parents are observed - slow
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157 if debug, fprintf('node %d is obs, some ps are obs\n', n); end
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158 for t=2:T
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159 CPDpot{n,t} = convert_to_table(bnet.CPD{e}, [ps self], evidence(:,t-1:t));
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160 end
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161 end
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162 end
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