1 | /*************************************************************************/ |
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2 | /* */ |
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3 | /* Determine the class of a case description from a decision tree */ |
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4 | /* -------------------------------------------------------------- */ |
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5 | /* */ |
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6 | /*************************************************************************/ |
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7 | |
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8 | |
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9 | #include "defns.i" |
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10 | #include "types.i" |
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11 | #include "extern.i" |
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12 | |
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13 | float *ClassSum=Nil; /* ClassSum[c] = total weight of class c */ |
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14 | |
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15 | |
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16 | |
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17 | /*************************************************************************/ |
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18 | /* */ |
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19 | /* Categorize a case description using the given decision tree */ |
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20 | /* */ |
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21 | /*************************************************************************/ |
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22 | |
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23 | |
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24 | ClassNo Category(CaseDesc, DecisionTree) |
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25 | /* -------- */ |
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26 | Description CaseDesc; |
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27 | Tree DecisionTree; |
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28 | { |
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29 | ClassNo c, BestClass; |
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30 | |
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31 | if ( ! ClassSum ) |
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32 | { |
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33 | ClassSum = (float *) malloc((MaxClass+1) * sizeof(float)); |
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34 | } |
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35 | |
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36 | ForEach(c, 0, MaxClass) |
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37 | { |
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38 | ClassSum[c] = 0; |
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39 | } |
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40 | |
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41 | Classify(CaseDesc, DecisionTree, 1.0); |
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42 | |
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43 | BestClass = 0; |
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44 | ForEach(c, 0, MaxClass) |
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45 | { |
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46 | Verbosity(5) printf("class %s weight %.2f\n", ClassName[c], ClassSum[c]); |
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47 | |
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48 | if ( ClassSum[c] > ClassSum[BestClass] ) BestClass = c; |
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49 | } |
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50 | |
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51 | return BestClass; |
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52 | } |
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53 | |
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54 | |
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55 | |
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56 | /*************************************************************************/ |
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57 | /* */ |
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58 | /* Classify a case description using the given subtree by adjusting */ |
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59 | /* the value ClassSum for each class */ |
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60 | /* */ |
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61 | /*************************************************************************/ |
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62 | |
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63 | |
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64 | Classify(CaseDesc, T, Weight) |
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65 | /* -------- */ |
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66 | Description CaseDesc; |
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67 | Tree T; |
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68 | float Weight; |
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69 | { |
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70 | DiscrValue v, dv; |
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71 | float Cv; |
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72 | Attribute a; |
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73 | ClassNo c; |
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74 | |
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75 | switch ( T->NodeType ) |
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76 | { |
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77 | case 0: /* leaf */ |
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78 | |
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79 | if ( T->Items > 0 ) |
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80 | { |
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81 | /* Update from ALL classes */ |
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82 | |
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83 | ForEach(c, 0, MaxClass) |
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84 | { |
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85 | if ( T->ClassDist[c] ) |
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86 | { |
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87 | ClassSum[c] += Weight * T->ClassDist[c] / T->Items; |
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88 | } |
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89 | } |
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90 | } |
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91 | else |
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92 | { |
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93 | ClassSum[T->Leaf] += Weight; |
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94 | } |
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95 | |
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96 | return; |
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97 | |
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98 | case BrDiscr: /* test of discrete attribute */ |
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99 | |
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100 | a = T->Tested; |
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101 | v = DVal(CaseDesc, a); |
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102 | |
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103 | if ( v && v <= T->Forks ) /* Make sure not new discrete value */ |
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104 | { |
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105 | Classify(CaseDesc, T->Branch[v], Weight); |
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106 | } |
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107 | else |
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108 | { |
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109 | ForEach(v, 1, T->Forks) |
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110 | { |
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111 | Classify(CaseDesc, T->Branch[v], |
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112 | (Weight * T->Branch[v]->Items) / T->Items); |
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113 | } |
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114 | } |
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115 | |
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116 | return; |
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117 | |
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118 | case ThreshContin: /* test of continuous attribute */ |
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119 | |
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120 | a = T->Tested; |
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121 | Cv = CVal(CaseDesc, a); |
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122 | |
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123 | if ( Cv == Unknown ) |
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124 | { |
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125 | ForEach(v, 1, 2) |
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126 | { |
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127 | Classify(CaseDesc, T->Branch[v], |
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128 | (Weight * T->Branch[v]->Items) / T->Items); |
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129 | } |
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130 | } |
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131 | else |
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132 | { |
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133 | v = ( Cv <= T->Cut ? 1 : 2 ); |
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134 | Classify(CaseDesc, T->Branch[v], Weight); |
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135 | } |
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136 | |
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137 | return; |
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138 | |
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139 | case BrSubset: /* subset test on discrete attribute */ |
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140 | |
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141 | a = T->Tested; |
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142 | dv = DVal(CaseDesc, a); |
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143 | |
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144 | if ( dv ) |
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145 | { |
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146 | ForEach(v, 1, T->Forks) |
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147 | { |
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148 | if ( In(dv, T->Subset[v]) ) |
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149 | { |
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150 | Classify(CaseDesc, T->Branch[v], Weight); |
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151 | |
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152 | return; |
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153 | } |
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154 | } |
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155 | } |
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156 | |
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157 | /* Value unknown or not found in any of the subsets */ |
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158 | |
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159 | ForEach(v, 1, T->Forks) |
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160 | { |
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161 | Classify(CaseDesc, T->Branch[v], |
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162 | (Weight * T->Branch[v]->Items) / T->Items); |
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163 | } |
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164 | |
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165 | return; |
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166 | } |
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167 | } |
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