1 | /*************************************************************************/ |
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2 | /* */ |
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3 | /* Process sets of rules */ |
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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 | #include "rulex.i" |
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13 | |
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14 | |
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15 | ItemNo *ClassFreq, /* ClassFreq[c] = no. items of class c */ |
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16 | *Covered, /* Covered[i] = no. included rules that cover item i */ |
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17 | *FalsePos, /* FalsePos[c] = no. false positives from rules |
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18 | selected for class c */ |
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19 | *NoRule, /* NoRule[c] = no. items covered by no selected rule */ |
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20 | |
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21 | *Right, /* Right[r] = no. correct rule firings */ |
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22 | *Wrong; /* Wrong[r] = no. incorrect rule firings */ |
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23 | |
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24 | float *Value, /* Value[r] = advantage attributable to rule r or |
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25 | realisable if rule r included */ |
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26 | SubsetValue, /* value of best class subset so far */ |
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27 | CodeWeight; /* multiplying factor for rule encodings */ |
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28 | |
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29 | Boolean *RuleIn, /* RuleIn[r] = true if rule r included */ |
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30 | *Subset, /* best class subset so far */ |
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31 | **Match; /* Match[r][i] = true if rule r fires on item i */ |
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32 | |
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33 | RuleNo *ClassRules; /* list of all rules for current target class */ |
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34 | |
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35 | ClassNo FocusClass; |
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36 | |
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37 | |
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38 | |
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39 | /*************************************************************************/ |
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40 | /* */ |
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41 | /* Construct an ordered subset (indexed by RuleIndex) of the current */ |
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42 | /* set of rules */ |
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43 | /* */ |
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44 | /*************************************************************************/ |
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45 | |
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46 | |
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47 | ConstructRuleset() |
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48 | /* ---------------- */ |
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49 | { |
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50 | RuleNo r, OldNRules = NRules; |
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51 | |
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52 | /* Allocate tables */ |
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53 | |
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54 | Right = (ItemNo *) calloc(NRules+1, sizeof(ItemNo)); |
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55 | Wrong = (ItemNo *) calloc(NRules+1, sizeof(ItemNo)); |
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56 | |
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57 | Value = (float *) calloc(NRules+1, sizeof(float)); |
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58 | |
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59 | RuleIn = (Boolean *) calloc(NRules+1, sizeof(Boolean)); |
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60 | Subset = (Boolean *) malloc((NRules+1) * sizeof(Boolean)); |
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61 | |
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62 | ClassRules = (RuleNo *) malloc((NRules+1) * sizeof(RuleNo)); |
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63 | |
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64 | ClassFreq = (ItemNo *) calloc(MaxClass+1, sizeof(ItemNo)); |
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65 | |
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66 | Covered = (ItemNo *) calloc(MaxItem+1, sizeof(ItemNo)); |
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67 | |
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68 | Match = (Boolean **) calloc(NRules+1, sizeof(Boolean *)); |
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69 | |
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70 | FalsePos = (ItemNo *) calloc(MaxClass+1, sizeof(ItemNo)); |
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71 | |
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72 | NoRule = (ItemNo *) calloc(MaxClass+1, sizeof(ItemNo)); |
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73 | |
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74 | ForEach(r, 1, NRules) |
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75 | { |
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76 | Match[r] = (Boolean *) calloc(MaxItem+1, sizeof(Boolean)); |
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77 | } |
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78 | |
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79 | /* Cover each class, then order the classes to give an index of rules */ |
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80 | |
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81 | InitialiseTables(); |
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82 | |
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83 | FindRuleCodes(); |
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84 | CodeWeight = 0.5; |
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85 | |
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86 | ForEach(FocusClass, 0, MaxClass) |
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87 | { |
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88 | CoverClass(); |
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89 | } |
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90 | |
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91 | MakeIndex(); |
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92 | FindDefault(); |
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93 | |
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94 | /* Clear */ |
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95 | |
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96 | cfree(Value); |
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97 | cfree(RuleIn); |
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98 | cfree(ClassRules); |
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99 | cfree(Subset); |
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100 | cfree(Covered); |
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101 | cfree(FalsePos); |
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102 | cfree(NoRule); |
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103 | ForEach(r, 1, OldNRules) |
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104 | { |
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105 | cfree(Match[r]); |
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106 | } |
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107 | cfree(Match); |
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108 | } |
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109 | |
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110 | |
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111 | |
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112 | /*************************************************************************/ |
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113 | /* */ |
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114 | /* Initialise all tables used in sifting */ |
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115 | /* */ |
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116 | /*************************************************************************/ |
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117 | |
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118 | |
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119 | InitialiseTables() |
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120 | /* ---------------- */ |
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121 | { |
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122 | ItemNo i; |
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123 | RuleNo r; |
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124 | ClassNo c; |
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125 | float Strength(); |
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126 | |
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127 | ForEach(r, 1, NRules) |
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128 | { |
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129 | RuleIn[r] = false; |
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130 | Rule[r].Used = Rule[r].Incorrect = 0; |
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131 | } |
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132 | |
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133 | ForEach(c, 0, MaxClass) |
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134 | { |
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135 | ClassFreq[c] = 0; |
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136 | } |
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137 | |
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138 | ForEach(i, 0, MaxItem) |
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139 | { |
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140 | ClassFreq[Class(Item[i])]++; |
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141 | |
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142 | ForEach(r, 1, NRules) |
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143 | { |
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144 | Match[r][i] = Strength(Rule[r], Item[i]) > 0.1; |
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145 | |
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146 | if ( Match[r][i] ) |
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147 | { |
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148 | Rule[r].Used++; |
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149 | if ( Class(Item[i]) != Rule[r].Rhs ) Rule[r].Incorrect++; |
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150 | } |
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151 | } |
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152 | } |
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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 | /*************************************************************************/ |
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158 | /* */ |
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159 | /* Select a subset of the rules for class FocusClass */ |
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160 | /* */ |
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161 | /*************************************************************************/ |
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162 | |
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163 | |
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164 | CoverClass() |
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165 | /* ---------- */ |
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166 | { |
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167 | RuleNo r, RuleCount=0; |
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168 | ItemNo i; |
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169 | |
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170 | Verbosity(1) |
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171 | printf("\nClass %s\n-----\nAction Change Value", |
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172 | ClassName[FocusClass]); |
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173 | |
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174 | ForEach(i, 0, MaxItem) |
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175 | { |
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176 | Covered[i] = 0; |
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177 | } |
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178 | |
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179 | ForEach(r, 1, NRules) |
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180 | { |
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181 | if ( Rule[r].Rhs == FocusClass ) |
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182 | { |
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183 | RuleCount++; |
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184 | ClassRules[RuleCount] = r; |
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185 | } |
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186 | } |
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187 | |
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188 | if ( ! RuleCount ) |
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189 | { |
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190 | return; |
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191 | } |
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192 | |
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193 | SubsetValue = 1E10; |
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194 | |
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195 | if ( RuleCount <= 10 ) |
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196 | { |
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197 | AllCombinations(RuleCount); |
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198 | } |
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199 | else |
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200 | if ( SIMANNEAL ) |
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201 | { |
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202 | SimAnneal(RuleCount); |
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203 | } |
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204 | else |
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205 | { |
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206 | SpotSearch(RuleCount); |
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207 | } |
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208 | |
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209 | memcpy(RuleIn, Subset, NRules+1); |
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210 | Verbosity(1) printf("\n\tBest value %.1f\n", SubsetValue); |
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211 | } |
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212 | |
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213 | |
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214 | |
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215 | /*************************************************************************/ |
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216 | /* */ |
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217 | /* Try all combinations of rules to find best value */ |
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218 | /* */ |
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219 | /*************************************************************************/ |
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220 | |
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221 | |
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222 | AllCombinations(NR) |
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223 | /* --------------- */ |
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224 | RuleNo NR; |
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225 | { |
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226 | RuleNo r; |
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227 | |
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228 | if ( ! NR ) |
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229 | { |
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230 | CalculateValue(); |
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231 | } |
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232 | else |
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233 | { |
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234 | r = ClassRules[NR]; |
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235 | |
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236 | AllCombinations(NR-1); |
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237 | |
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238 | AddRule(r); |
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239 | AllCombinations(NR-1); |
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240 | |
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241 | DeleteRule(r); |
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242 | Verbosity(1) printf("\n"); |
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243 | } |
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244 | } |
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245 | |
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246 | |
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247 | |
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248 | /*************************************************************************/ |
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249 | /* */ |
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250 | /* Find a good subset by simulated annealing */ |
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251 | /* */ |
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252 | /*************************************************************************/ |
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253 | |
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254 | |
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255 | SimAnneal(RuleCount) |
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256 | /* --------- */ |
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257 | RuleNo RuleCount; |
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258 | { |
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259 | RuleNo r, OutCount; |
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260 | short ri, Tries; |
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261 | float Temp, Delta; |
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262 | Boolean Changed; |
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263 | |
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264 | /* Keep dropping and adding rules until can't improve */ |
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265 | |
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266 | for ( Temp = 1000 ; Temp > 0.001 ; Temp *= 0.95 ) |
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267 | { |
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268 | CalculateValue(); |
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269 | |
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270 | Verbosity(2) |
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271 | { |
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272 | OutCount = 0; |
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273 | |
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274 | ForEach(ri, 1, RuleCount) |
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275 | { |
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276 | r = ClassRules[ri]; |
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277 | |
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278 | if ( ! RuleIn[r] ) |
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279 | { |
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280 | if ( ! (OutCount++ % 3) ) printf("\n\t\t"); |
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281 | printf("%d<%d|%d=%.1f> ", r, Right[r], Wrong[r], Value[r]); |
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282 | } |
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283 | } |
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284 | |
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285 | printf("\n\n"); |
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286 | } |
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287 | |
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288 | Changed = false; |
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289 | |
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290 | for ( Tries = 100 ; ! Changed && Tries > 0 ; Tries-- ) |
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291 | { |
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292 | /* Choose a rule to add or delete */ |
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293 | |
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294 | ri = RuleCount * Random + 1; |
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295 | |
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296 | r = ClassRules[ri]; |
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297 | |
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298 | Delta = ( RuleIn[r] ? -Value[r] : Value[r] ); |
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299 | |
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300 | if ( Delta > 0 || Random < exp(Delta / Temp) ) |
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301 | { |
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302 | if ( RuleIn[r] ) |
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303 | { |
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304 | DeleteRule(r); |
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305 | } |
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306 | else |
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307 | { |
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308 | AddRule(r); |
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309 | } |
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310 | |
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311 | Changed = true; |
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312 | } |
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313 | } |
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314 | |
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315 | if ( ! Changed ) break; |
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316 | } |
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317 | |
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318 | /* Try to improve best subset so far by hill-climbing */ |
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319 | |
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320 | Verbosity(1) printf("Polish: "); |
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321 | memcpy(RuleIn, Subset, NRules+1); |
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322 | HillClimb(RuleCount); |
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323 | } |
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324 | |
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325 | |
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326 | |
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327 | /*************************************************************************/ |
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328 | /* */ |
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329 | /* Find a good subset by repeated greedy search */ |
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330 | /* */ |
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331 | /*************************************************************************/ |
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332 | |
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333 | |
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334 | SpotSearch(RuleCount) |
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335 | /* ---------- */ |
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336 | RuleNo RuleCount; |
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337 | { |
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338 | RuleNo r; |
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339 | short ri, Trial; |
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340 | float ProbIn; |
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341 | |
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342 | ForEach(Trial, 0, 10) |
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343 | { |
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344 | Verbosity(1) printf("\n Trial %d:", Trial); |
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345 | |
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346 | /* Add rules randomly to the initial subset */ |
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347 | |
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348 | ProbIn = Trial / 10.0; |
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349 | ForEach(ri, 1, RuleCount) |
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350 | { |
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351 | r = ClassRules[ri]; |
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352 | RuleIn[r] = Random < ProbIn; |
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353 | } |
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354 | |
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355 | HillClimb(RuleCount); |
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356 | } |
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357 | } |
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358 | |
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359 | |
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360 | |
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361 | /*************************************************************************/ |
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362 | /* */ |
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363 | /* Improve a subset of rules by adding and deleting rules */ |
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364 | /* */ |
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365 | /*************************************************************************/ |
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366 | |
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367 | |
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368 | HillClimb(RuleCount) |
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369 | /* --------- */ |
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370 | RuleNo RuleCount; |
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371 | { |
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372 | RuleNo r, Bestr; |
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373 | short ri, OutCount; |
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374 | ItemNo i; |
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375 | float Delta, BestDelta; |
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376 | |
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377 | ForEach(i, 0, MaxItem) |
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378 | { |
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379 | Covered[i] = 0; |
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380 | } |
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381 | |
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382 | ForEach(ri, 1, RuleCount) |
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383 | { |
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384 | r = ClassRules[ri]; |
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385 | if ( RuleIn[r] ) |
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386 | { |
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387 | ForEach(i, 0, MaxItem) |
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388 | { |
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389 | if ( Match[r][i] ) |
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390 | { |
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391 | Covered[i]++; |
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392 | } |
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393 | } |
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394 | } |
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395 | } |
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396 | |
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397 | /* Add or drop rule with greatest reduction in coding cost */ |
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398 | |
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399 | while ( true ) |
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400 | { |
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401 | CalculateValue(); |
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402 | |
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403 | Verbosity(2) |
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404 | { |
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405 | OutCount = 0; |
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406 | |
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407 | ForEach(ri, 1, RuleCount) |
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408 | { |
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409 | r = ClassRules[ri]; |
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410 | |
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411 | if ( ! RuleIn[r] ) |
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412 | { |
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413 | if ( ! (OutCount++ % 3) ) printf("\n\t\t"); |
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414 | printf("%d<%d|%d=%.1f> ", r, Right[r], Wrong[r], Value[r]); |
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415 | } |
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416 | } |
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417 | |
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418 | printf("\n\n"); |
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419 | } |
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420 | |
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421 | Bestr = BestDelta = 0; |
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422 | ForEach(ri, 1, RuleCount) |
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423 | { |
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424 | r = ClassRules[ri]; |
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425 | Delta = ( RuleIn[r] ? -Value[r] : Value[r] ); |
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426 | if ( Delta > BestDelta ) |
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427 | { |
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428 | Bestr = r; |
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429 | BestDelta = Delta; |
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430 | } |
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431 | } |
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432 | if ( ! Bestr ) break; |
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433 | |
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434 | if ( RuleIn[Bestr] ) |
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435 | { |
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436 | DeleteRule(Bestr); |
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437 | } |
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438 | else |
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439 | { |
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440 | AddRule(Bestr); |
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441 | } |
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442 | } |
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443 | } |
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444 | |
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445 | |
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446 | |
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447 | /*************************************************************************/ |
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448 | /* */ |
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449 | /* Find the number of correct and incorrect rule firings for rules */ |
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450 | /* for class FocusClass and hence determine the Value of the rules. */ |
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451 | /* If best so far, remember. */ |
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452 | /* */ |
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453 | /*************************************************************************/ |
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454 | |
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455 | |
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456 | CalculateValue() |
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457 | /* -------------- */ |
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458 | { |
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459 | RuleNo r, Selected=0, InCount; |
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460 | ItemNo i, Times, FPos=0, FNeg=0, SumCover=0; |
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461 | float BaseBits, RuleBits=0, NewBits, ExceptionBits(); |
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462 | ClassNo ThisClass; |
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463 | Boolean *RuleMatch; |
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464 | |
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465 | ForEach(i, 0, MaxItem) |
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466 | { |
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467 | ThisClass = Class(Item[i]); |
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468 | |
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469 | if ( Covered[i] ) |
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470 | { |
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471 | SumCover++; |
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472 | if( ThisClass != FocusClass ) FPos++; |
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473 | } |
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474 | else |
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475 | if ( ThisClass == FocusClass ) |
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476 | { |
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477 | FNeg++; |
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478 | } |
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479 | } |
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480 | |
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481 | ForEach(r, 1, NRules) |
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482 | { |
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483 | if ( Rule[r].Rhs == FocusClass ) |
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484 | { |
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485 | Right[r] = Wrong[r] = 0; |
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486 | |
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487 | if ( RuleIn[r] ) |
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488 | { |
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489 | RuleBits += Rule[r].Bits; |
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490 | Selected++; |
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491 | } |
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492 | |
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493 | RuleMatch = Match[r]; |
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494 | |
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495 | ForEach(i, 0, MaxItem) |
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496 | { |
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497 | if ( RuleMatch[i] && |
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498 | ( ! (Times = Covered[i]) || Times == 1 && RuleIn[r] ) ) |
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499 | { |
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500 | if ( Class(Item[i]) == FocusClass ) |
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501 | { |
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502 | Right[r]++; |
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503 | } |
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504 | else |
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505 | { |
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506 | Wrong[r]++; |
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507 | } |
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508 | } |
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509 | } |
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510 | } |
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511 | } |
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512 | |
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513 | RuleBits -= LogFact[Selected]; /* allow for reordering of rules */ |
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514 | |
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515 | BaseBits = CodeWeight * RuleBits + ExceptionBits(SumCover, FPos, FNeg); |
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516 | |
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517 | /* From the Right and Wrong of each rule, calculate its value */ |
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518 | |
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519 | Verbosity(1) |
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520 | { |
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521 | printf("\t"); |
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522 | InCount = -1; |
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523 | } |
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524 | |
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525 | ForEach(r, 1, NRules) |
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526 | { |
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527 | if ( Rule[r].Rhs == FocusClass ) |
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528 | { |
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529 | if ( RuleIn[r] ) |
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530 | { |
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531 | NewBits = ExceptionBits(SumCover-Right[r]-Wrong[r], |
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532 | FPos-Wrong[r], FNeg+Right[r]) + |
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533 | CodeWeight * |
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534 | (RuleBits - Rule[r].Bits + LogItemNo[Selected]); |
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535 | Value[r] = NewBits - BaseBits; |
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536 | } |
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537 | else |
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538 | { |
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539 | NewBits = ExceptionBits(SumCover+Right[r]+Wrong[r], |
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540 | FPos+Wrong[r], FNeg-Right[r]) + |
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541 | CodeWeight * |
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542 | (RuleBits + Rule[r].Bits - LogItemNo[Selected+1]); |
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543 | Value[r] = BaseBits - NewBits; |
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544 | } |
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545 | |
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546 | Verbosity(1) |
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547 | { |
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548 | if ( RuleIn[r] ) |
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549 | { |
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550 | if ( ++InCount && ! (InCount % 3) ) printf("\n\t\t"); |
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551 | printf("%d[%d|%d=%.1f] ", r, Right[r], Wrong[r], Value[r]); |
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552 | } |
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553 | } |
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554 | } |
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555 | } |
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556 | |
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557 | Verbosity(1) |
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558 | { |
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559 | printf("\n\t\t%d rules, %d firings: F+=%d, F-=%d, %.1f bits (rules=%.1f)\n", |
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560 | Selected, SumCover, FPos, FNeg, BaseBits, RuleBits); |
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561 | } |
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562 | |
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563 | if ( BaseBits < SubsetValue ) |
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564 | { |
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565 | SubsetValue = BaseBits; |
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566 | memcpy(Subset, RuleIn, NRules+1); |
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567 | } |
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568 | } |
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569 | |
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570 | |
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571 | |
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572 | /*************************************************************************/ |
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573 | /* */ |
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574 | /* Add rule r to the set of included rules and increase the number of */ |
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575 | /* rules covering each of the items that fire the rule */ |
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576 | /* */ |
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577 | /*************************************************************************/ |
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578 | |
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579 | |
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580 | AddRule(r) |
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581 | /* ------- */ |
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582 | RuleNo r; |
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583 | { |
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584 | ItemNo i; |
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585 | |
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586 | RuleIn[r] = true; |
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587 | |
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588 | ForEach(i, 0, MaxItem) |
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589 | { |
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590 | if ( Match[r][i] ) |
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591 | { |
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592 | Covered[i]++; |
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593 | } |
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594 | } |
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595 | |
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596 | Verbosity(1) printf("%5d+ %6.1f", r, Value[r]); |
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597 | } |
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598 | |
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599 | |
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600 | |
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601 | /*************************************************************************/ |
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602 | /* */ |
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603 | /* Delete rule r from the included rules and decrease the number of */ |
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604 | /* rules covering each of the items covered by the rule */ |
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605 | /* */ |
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606 | /*************************************************************************/ |
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607 | |
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608 | |
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609 | DeleteRule(r) |
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610 | /* ---------- */ |
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611 | RuleNo r; |
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612 | { |
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613 | ItemNo i; |
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614 | |
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615 | RuleIn[r] = false; |
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616 | |
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617 | ForEach(i, 0, MaxItem) |
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618 | { |
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619 | if ( Match[r][i] ) |
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620 | { |
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621 | Covered[i]--; |
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622 | } |
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623 | } |
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624 | |
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625 | Verbosity(1) printf("%5d- %6.1f", r, -Value[r]); |
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626 | } |
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627 | |
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628 | |
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629 | |
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630 | /*************************************************************************/ |
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631 | /* */ |
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632 | /* Make an index of included rules in RuleIndex. Select first those */ |
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633 | /* classes whose rules have the fewest false positives. Within a */ |
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634 | /* class, put rules with higher accuracy ahead. */ |
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635 | /* */ |
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636 | /*************************************************************************/ |
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637 | |
---|
638 | |
---|
639 | MakeIndex() |
---|
640 | /* --------- */ |
---|
641 | { |
---|
642 | ClassNo c, BestC, Pass; |
---|
643 | RuleNo r, BestR, NewNRules = 0; |
---|
644 | ItemNo i; |
---|
645 | Boolean *Included; |
---|
646 | |
---|
647 | Included = (Boolean *) calloc(MaxClass+1, sizeof(Boolean)); |
---|
648 | RuleIndex = (RuleNo *) calloc(NRules+1, sizeof(RuleNo)); |
---|
649 | |
---|
650 | Verbosity(1) printf("\nFalsePos Class\n"); |
---|
651 | |
---|
652 | ForEach(i, 0, MaxItem) |
---|
653 | { |
---|
654 | Covered[i] = 0; |
---|
655 | } |
---|
656 | |
---|
657 | /* Select the best class to put next */ |
---|
658 | |
---|
659 | ForEach(Pass, 0, MaxClass) |
---|
660 | { |
---|
661 | ForEach(c, 0, MaxClass) |
---|
662 | { |
---|
663 | if ( Included[c] ) continue; |
---|
664 | |
---|
665 | FalsePos[c] = 0; |
---|
666 | |
---|
667 | ForEach(i, 0, MaxItem) |
---|
668 | { |
---|
669 | if ( Covered[i] || Class(Item[i]) == c ) continue; |
---|
670 | |
---|
671 | ForEach(r, 1, NRules) |
---|
672 | { |
---|
673 | if ( Rule[r].Rhs == c && RuleIn[r] && Match[r][i] ) |
---|
674 | { |
---|
675 | FalsePos[c]++; |
---|
676 | break; |
---|
677 | } |
---|
678 | } |
---|
679 | } |
---|
680 | } |
---|
681 | |
---|
682 | BestC = -1; |
---|
683 | ForEach(c, 0, MaxClass) |
---|
684 | { |
---|
685 | if ( ! Included[c] && |
---|
686 | ( BestC < 0 || FalsePos[c] < FalsePos[BestC] ) ) |
---|
687 | { |
---|
688 | BestC = c; |
---|
689 | } |
---|
690 | } |
---|
691 | Included[BestC] = true; |
---|
692 | |
---|
693 | Verbosity(1) |
---|
694 | printf("%5d %s\n", FalsePos[BestC], ClassName[BestC]); |
---|
695 | |
---|
696 | /* Now grab the rules for this class */ |
---|
697 | |
---|
698 | do |
---|
699 | { |
---|
700 | BestR = 0; |
---|
701 | |
---|
702 | /* Find the best rule to put next */ |
---|
703 | |
---|
704 | ForEach(r, 1, NRules) |
---|
705 | { |
---|
706 | if ( RuleIn[r] && Rule[r].Rhs == BestC && |
---|
707 | ( ! BestR || Rule[r].Error < Rule[BestR].Error ) ) |
---|
708 | { |
---|
709 | BestR = r; |
---|
710 | } |
---|
711 | } |
---|
712 | |
---|
713 | if ( BestR ) |
---|
714 | { |
---|
715 | RuleIndex[++NewNRules] = BestR; |
---|
716 | RuleIn[BestR] = false; |
---|
717 | |
---|
718 | ForEach(i, 0, MaxItem) |
---|
719 | { |
---|
720 | Covered[i] |= Match[BestR][i]; |
---|
721 | } |
---|
722 | } |
---|
723 | } while ( BestR ); |
---|
724 | } |
---|
725 | |
---|
726 | NRules = NewNRules; |
---|
727 | cfree(Included); |
---|
728 | } |
---|
729 | |
---|
730 | |
---|
731 | |
---|
732 | /*************************************************************************/ |
---|
733 | /* */ |
---|
734 | /* Find the default class as the one with most items not covered by */ |
---|
735 | /* any rule. Resolve ties in favour of more frequent classes. */ |
---|
736 | /* (Note: Covered has been set by MakeIndex.) */ |
---|
737 | /* */ |
---|
738 | /*************************************************************************/ |
---|
739 | |
---|
740 | |
---|
741 | FindDefault() |
---|
742 | /* ----------- */ |
---|
743 | { |
---|
744 | ClassNo c; |
---|
745 | ItemNo i; |
---|
746 | |
---|
747 | /* Determine uncovered items */ |
---|
748 | |
---|
749 | ForEach(c, 0, MaxClass) |
---|
750 | { |
---|
751 | NoRule[c] = 0; |
---|
752 | } |
---|
753 | |
---|
754 | ForEach(i, 0, MaxItem) |
---|
755 | { |
---|
756 | if ( ! Covered[i] ) |
---|
757 | { |
---|
758 | NoRule[Class(Item[i])]++; |
---|
759 | } |
---|
760 | } |
---|
761 | |
---|
762 | Verbosity(1) |
---|
763 | { |
---|
764 | printf("\nItems: Uncovered Class\n"); |
---|
765 | ForEach(c, 0, MaxClass) |
---|
766 | { |
---|
767 | printf("%5d %7d %s\n", ClassFreq[c], NoRule[c], ClassName[c]); |
---|
768 | } |
---|
769 | printf("\n"); |
---|
770 | } |
---|
771 | |
---|
772 | DefaultClass = 0; |
---|
773 | ForEach(c, 1, MaxClass) |
---|
774 | { |
---|
775 | if ( NoRule[c] > NoRule[DefaultClass] || |
---|
776 | NoRule[c] == NoRule[DefaultClass] && |
---|
777 | ClassFreq[c] > ClassFreq[DefaultClass] ) |
---|
778 | { |
---|
779 | DefaultClass = c; |
---|
780 | } |
---|
781 | } |
---|
782 | } |
---|
783 | |
---|
784 | |
---|
785 | |
---|
786 | /*************************************************************************/ |
---|
787 | /* */ |
---|
788 | /* Given a rule and a case, determine the strength with which we can */ |
---|
789 | /* conclude that the case belongs to the class specified by the rule's */ |
---|
790 | /* right-hand side. */ |
---|
791 | /* */ |
---|
792 | /* If the case doesn't satisfy all the conditions of the rule, */ |
---|
793 | /* then this is 0. */ |
---|
794 | /* */ |
---|
795 | /*************************************************************************/ |
---|
796 | |
---|
797 | |
---|
798 | float Strength(ThisRule, Case) |
---|
799 | /* -------- */ |
---|
800 | PR ThisRule; |
---|
801 | Description Case; |
---|
802 | { |
---|
803 | short d; |
---|
804 | Boolean Satisfies(); |
---|
805 | |
---|
806 | if ( ThisRule.Error > 0.7 ) return 0.0; |
---|
807 | |
---|
808 | ForEach(d, 1, ThisRule.Size) |
---|
809 | { |
---|
810 | if ( ! Satisfies(Case, ThisRule.Lhs[d]) ) |
---|
811 | { |
---|
812 | return 0.0; |
---|
813 | } |
---|
814 | } |
---|
815 | |
---|
816 | return ( 1 - ThisRule.Error ); |
---|
817 | } |
---|
818 | |
---|
819 | |
---|
820 | |
---|
821 | /*************************************************************************/ |
---|
822 | /* */ |
---|
823 | /* Determine the number of bits to encode exceptions. Unlike the */ |
---|
824 | /* version in the book, this uses an approximate encoding that */ |
---|
825 | /* penalizes unbalanced numbers of false positives and false negatives */ |
---|
826 | /* as described in my paper at 1995 International Machine Learning */ |
---|
827 | /* Conference (published by Morgan Kaufmann). */ |
---|
828 | /* */ |
---|
829 | /*************************************************************************/ |
---|
830 | |
---|
831 | |
---|
832 | float Biased(N, E, ExpE) |
---|
833 | /* ------ */ |
---|
834 | int N, E; |
---|
835 | float ExpE; |
---|
836 | { |
---|
837 | float Rate; |
---|
838 | |
---|
839 | if ( ExpE <= 1E-6 ) |
---|
840 | { |
---|
841 | return ( E == 0 ? 0.0 : 1E6 ); |
---|
842 | } |
---|
843 | else |
---|
844 | if ( ExpE >= N-1E-6 ) |
---|
845 | { |
---|
846 | return ( E == N ? 0.0 : 1E6 ); |
---|
847 | } |
---|
848 | |
---|
849 | Rate = ExpE / N; |
---|
850 | return -E * Log(Rate) - (N-E) * Log(1-Rate); |
---|
851 | } |
---|
852 | |
---|
853 | |
---|
854 | |
---|
855 | float ExceptionBits(Fires, FP, FN) |
---|
856 | /* ------------- */ |
---|
857 | int Fires, FP, FN; |
---|
858 | { |
---|
859 | if ( Fires > 0.5 * (MaxItem+1) ) |
---|
860 | { |
---|
861 | return Log(MaxItem+1) |
---|
862 | + Biased(Fires, FP, 0.5 * (FP+FN)) |
---|
863 | + Biased(MaxItem+1-Fires, FN, (float) FN); |
---|
864 | } |
---|
865 | else |
---|
866 | { |
---|
867 | return Log(MaxItem+1) |
---|
868 | + Biased(Fires, FP, (float) FP) |
---|
869 | + Biased(MaxItem+1-Fires, FN, 0.5 * (FP+FN)); |
---|
870 | } |
---|
871 | } |
---|
872 | |
---|
873 | |
---|
874 | |
---|
875 | /*************************************************************************/ |
---|
876 | /* */ |
---|
877 | /* Find encoding lengths for all rules */ |
---|
878 | /* */ |
---|
879 | /*************************************************************************/ |
---|
880 | |
---|
881 | |
---|
882 | FindRuleCodes() |
---|
883 | /* ------------- */ |
---|
884 | { |
---|
885 | RuleNo r; |
---|
886 | short d, NCond; |
---|
887 | float Bits, CondBits(); |
---|
888 | |
---|
889 | ForEach(r, 1, NRules) |
---|
890 | { |
---|
891 | NCond = Rule[r].Size; |
---|
892 | Bits = 0; |
---|
893 | |
---|
894 | ForEach(d, 1, NCond) |
---|
895 | { |
---|
896 | Bits += CondBits(Rule[r].Lhs[d]); |
---|
897 | } |
---|
898 | |
---|
899 | /* Must encode the number of conditions, but credit the total |
---|
900 | encoding by the ways conditions can be reordered */ |
---|
901 | |
---|
902 | Rule[r].Bits = Bits + LogItemNo[NCond] - LogFact[NCond]; |
---|
903 | } |
---|
904 | } |
---|
905 | |
---|
906 | |
---|
907 | |
---|
908 | /*************************************************************************/ |
---|
909 | /* */ |
---|
910 | /* Determine the number of bits required to encode a condition */ |
---|
911 | /* */ |
---|
912 | /*************************************************************************/ |
---|
913 | |
---|
914 | |
---|
915 | float CondBits(C) |
---|
916 | /* -------- */ |
---|
917 | Condition C; |
---|
918 | { |
---|
919 | Test t; |
---|
920 | Attribute a; |
---|
921 | |
---|
922 | t = C->CondTest; |
---|
923 | a = t->Tested; |
---|
924 | |
---|
925 | switch ( t->NodeType ) |
---|
926 | { |
---|
927 | case BrDiscr: /* test of discrete attribute */ |
---|
928 | case ThreshContin: /* test of continuous attribute */ |
---|
929 | |
---|
930 | return AttTestBits/REDUNDANCY + BranchBits[a]; |
---|
931 | |
---|
932 | case BrSubset: /* subset test on discrete attribute */ |
---|
933 | |
---|
934 | return AttTestBits/REDUNDANCY + MaxAttVal[a]; |
---|
935 | } |
---|
936 | } |
---|