1 | /*************************************************************************/ |
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2 | /* */ |
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3 | /* Routines to manage tree growth, pruning and evaluation */ |
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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 | |
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14 | ItemNo *TargetClassFreq; |
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15 | Tree *Raw; |
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16 | extern Tree *Pruned; |
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17 | |
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18 | |
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19 | |
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20 | /*************************************************************************/ |
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21 | /* */ |
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22 | /* Grow and prune a single tree from all data */ |
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23 | /* */ |
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24 | /*************************************************************************/ |
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25 | |
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26 | |
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27 | OneTree() |
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28 | /* --------- */ |
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29 | { |
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30 | Tree FormTree(), CopyTree(); |
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31 | Boolean Prune(); |
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32 | |
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33 | InitialiseTreeData(); |
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34 | InitialiseWeights(); |
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35 | |
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36 | Raw = (Tree *) calloc(1, sizeof(Tree)); |
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37 | Pruned = (Tree *) calloc(1, sizeof(Tree)); |
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38 | |
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39 | AllKnown = true; |
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40 | Raw[0] = FormTree(0, MaxItem); |
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41 | printf("\n"); |
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42 | PrintTree(Raw[0]); |
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43 | |
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44 | SaveTree(Raw[0], ".unpruned"); |
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45 | |
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46 | Pruned[0] = CopyTree(Raw[0]); |
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47 | if ( Prune(Pruned[0]) ) |
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48 | { |
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49 | printf("\nSimplified "); |
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50 | PrintTree(Pruned[0]); |
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51 | } |
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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 | /* Grow and prune TRIALS trees and select the best of them */ |
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59 | /* */ |
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60 | /*************************************************************************/ |
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61 | |
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62 | |
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63 | short BestTree() |
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64 | /* -------- */ |
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65 | { |
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66 | Tree CopyTree(), Iterate(); |
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67 | Boolean Prune(); |
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68 | short t, Best=0; |
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69 | |
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70 | InitialiseTreeData(); |
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71 | |
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72 | TargetClassFreq = (ItemNo *) calloc(MaxClass+1, sizeof(ItemNo)); |
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73 | |
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74 | Raw = (Tree *) calloc(TRIALS, sizeof(Tree)); |
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75 | Pruned = (Tree *) calloc(TRIALS, sizeof(Tree)); |
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76 | |
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77 | /* If necessary, set initial size of window to 20% (or twice |
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78 | the sqrt, if this is larger) of the number of data items, |
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79 | and the maximum number of items that can be added to the |
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80 | window at each iteration to 20% of the initial window size */ |
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81 | |
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82 | if ( ! WINDOW ) |
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83 | { |
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84 | WINDOW = Max(2 * sqrt(MaxItem+1.0), (MaxItem+1) / 5); |
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85 | } |
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86 | |
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87 | if ( ! INCREMENT ) |
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88 | { |
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89 | INCREMENT = Max(WINDOW / 5, 1); |
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90 | } |
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91 | |
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92 | FormTarget(WINDOW); |
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93 | |
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94 | /* Form set of trees by iteration and prune */ |
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95 | |
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96 | ForEach(t, 0, TRIALS-1 ) |
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97 | { |
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98 | FormInitialWindow(); |
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99 | |
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100 | printf("\n--------\nTrial %d\n--------\n\n", t); |
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101 | |
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102 | Raw[t] = Iterate(WINDOW, INCREMENT); |
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103 | printf("\n"); |
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104 | PrintTree(Raw[t]); |
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105 | |
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106 | SaveTree(Raw[t], ".unpruned"); |
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107 | |
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108 | Pruned[t] = CopyTree(Raw[t]); |
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109 | if ( Prune(Pruned[t]) ) |
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110 | { |
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111 | printf("\nSimplified "); |
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112 | PrintTree(Pruned[t]); |
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113 | } |
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114 | |
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115 | if ( Pruned[t]->Errors < Pruned[Best]->Errors ) |
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116 | { |
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117 | Best = t; |
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118 | } |
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119 | } |
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120 | printf("\n--------\n"); |
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121 | |
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122 | return Best; |
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123 | } |
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124 | |
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125 | |
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126 | |
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127 | /*************************************************************************/ |
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128 | /* */ |
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129 | /* The windowing approach seems to work best when the class */ |
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130 | /* distribution of the initial window is as close to uniform as */ |
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131 | /* possible. FormTarget generates this initial target distribution, */ |
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132 | /* setting up a TargetClassFreq value for each class. */ |
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133 | /* */ |
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134 | /*************************************************************************/ |
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135 | |
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136 | |
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137 | FormTarget(Size) |
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138 | /* ----------- */ |
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139 | ItemNo Size; |
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140 | { |
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141 | ItemNo i, *ClassFreq; |
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142 | ClassNo c, Smallest, ClassesLeft=0; |
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143 | |
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144 | ClassFreq = (ItemNo *) calloc(MaxClass+1, sizeof(ItemNo)); |
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145 | |
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146 | /* Generate the class frequency distribution */ |
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147 | |
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148 | ForEach(i, 0, MaxItem) |
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149 | { |
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150 | ClassFreq[ Class(Item[i]) ]++; |
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151 | } |
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152 | |
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153 | /* Calculate the no. of classes of which there are items */ |
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154 | |
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155 | ForEach(c, 0, MaxClass) |
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156 | { |
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157 | if ( ClassFreq[c] ) |
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158 | { |
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159 | ClassesLeft++; |
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160 | } |
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161 | else |
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162 | { |
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163 | TargetClassFreq[c] = 0; |
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164 | } |
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165 | } |
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166 | |
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167 | while ( ClassesLeft ) |
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168 | { |
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169 | /* Find least common class of which there are some items */ |
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170 | |
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171 | Smallest = -1; |
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172 | ForEach(c, 0, MaxClass) |
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173 | { |
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174 | if ( ClassFreq[c] && |
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175 | ( Smallest < 0 || ClassFreq[c] < ClassFreq[Smallest] ) ) |
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176 | { |
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177 | Smallest = c; |
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178 | } |
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179 | } |
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180 | |
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181 | /* Allocate the no. of items of this class to use in the window */ |
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182 | |
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183 | TargetClassFreq[Smallest] = Min(ClassFreq[Smallest], Round(Size/ClassesLeft)); |
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184 | |
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185 | ClassFreq[Smallest] = 0; |
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186 | |
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187 | Size -= TargetClassFreq[Smallest]; |
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188 | ClassesLeft--; |
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189 | } |
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190 | |
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191 | cfree(ClassFreq); |
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192 | } |
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193 | |
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194 | |
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195 | |
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196 | /*************************************************************************/ |
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197 | /* */ |
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198 | /* Form initial window, attempting to obtain the target class profile */ |
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199 | /* in TargetClassFreq. This is done by placing the targeted number */ |
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200 | /* of items of each class at the beginning of the set of data items. */ |
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201 | /* */ |
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202 | /*************************************************************************/ |
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203 | |
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204 | |
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205 | FormInitialWindow() |
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206 | /* ------------------- */ |
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207 | { |
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208 | ItemNo i, Start=0, More; |
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209 | ClassNo c; |
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210 | void Swap(); |
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211 | |
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212 | Shuffle(); |
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213 | |
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214 | ForEach(c, 0, MaxClass) |
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215 | { |
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216 | More = TargetClassFreq[c]; |
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217 | |
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218 | for ( i = Start ; More ; i++ ) |
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219 | { |
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220 | if ( Class(Item[i]) == c ) |
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221 | { |
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222 | Swap(Start, i); |
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223 | Start++; |
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224 | More--; |
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225 | } |
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226 | } |
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227 | } |
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228 | } |
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229 | |
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230 | |
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231 | |
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232 | /*************************************************************************/ |
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233 | /* */ |
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234 | /* Shuffle the data items randomly */ |
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235 | /* */ |
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236 | /*************************************************************************/ |
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237 | |
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238 | |
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239 | Shuffle() |
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240 | /* ------- */ |
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241 | { |
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242 | ItemNo This, Alt, Left; |
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243 | Description Hold; |
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244 | |
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245 | This = 0; |
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246 | for( Left = MaxItem+1 ; Left ; ) |
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247 | { |
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248 | Alt = This + (Left--) * Random; |
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249 | Hold = Item[This]; |
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250 | Item[This++] = Item[Alt]; |
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251 | Item[Alt] = Hold; |
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252 | } |
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253 | } |
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254 | |
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255 | |
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256 | |
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257 | /*************************************************************************/ |
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258 | /* */ |
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259 | /* Grow a tree iteratively with initial window size Window and */ |
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260 | /* initial window increment IncExceptions. */ |
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261 | /* */ |
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262 | /* Construct a classifier tree using the data items in the */ |
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263 | /* window, then test for the successful classification of other */ |
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264 | /* data items by this tree. If there are misclassified items, */ |
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265 | /* put them immediately after the items in the window, increase */ |
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266 | /* the size of the window and build another classifier tree, and */ |
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267 | /* so on until we have a tree which successfully classifies all */ |
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268 | /* of the test items or no improvement is apparent. */ |
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269 | /* */ |
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270 | /* On completion, return the tree which produced the least errors. */ |
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271 | /* */ |
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272 | /*************************************************************************/ |
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273 | |
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274 | |
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275 | Tree Iterate(Window, IncExceptions) |
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276 | /* ------- */ |
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277 | ItemNo Window, IncExceptions; |
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278 | { |
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279 | Tree Classifier, BestClassifier=Nil, FormTree(); |
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280 | ItemNo i, Errors, TotalErrors, BestTotalErrors=MaxItem+1, |
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281 | Exceptions, Additions; |
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282 | ClassNo Assigned, Category(); |
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283 | short Cycle=0; |
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284 | void Swap(); |
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285 | |
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286 | printf("Cycle Tree -----Cases----"); |
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287 | printf(" -----------------Errors-----------------\n"); |
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288 | printf(" size window other"); |
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289 | printf(" window rate other rate total rate\n"); |
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290 | printf("----- ---- ------ ------"); |
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291 | printf(" ------ ---- ------ ---- ------ ----\n"); |
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292 | |
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293 | do |
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294 | { |
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295 | /* Build a classifier tree with the first Window items */ |
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296 | |
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297 | InitialiseWeights(); |
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298 | AllKnown = true; |
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299 | Classifier = FormTree(0, Window-1); |
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300 | |
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301 | /* Error analysis */ |
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302 | |
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303 | Errors = Round(Classifier->Errors); |
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304 | |
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305 | /* Move all items that are incorrectly classified by the |
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306 | classifier tree to immediately after the items in the |
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307 | current window. */ |
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308 | |
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309 | Exceptions = Window; |
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310 | ForEach(i, Window, MaxItem) |
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311 | { |
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312 | Assigned = Category(Item[i], Classifier); |
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313 | if ( Assigned != Class(Item[i]) ) |
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314 | { |
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315 | Swap(Exceptions, i); |
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316 | Exceptions++; |
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317 | } |
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318 | } |
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319 | Exceptions -= Window; |
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320 | TotalErrors = Errors + Exceptions; |
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321 | |
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322 | /* Print error analysis */ |
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323 | |
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324 | printf("%3d %7d %8d %6d %8d%5.1f%% %6d%5.1f%% %6d%5.1f%%\n", |
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325 | ++Cycle, TreeSize(Classifier), Window, MaxItem-Window+1, |
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326 | Errors, 100*(float)Errors/Window, |
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327 | Exceptions, 100*Exceptions/(MaxItem-Window+1.001), |
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328 | TotalErrors, 100*TotalErrors/(MaxItem+1.0)); |
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329 | |
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330 | /* Keep track of the most successful classifier tree so far */ |
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331 | |
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332 | if ( ! BestClassifier || TotalErrors < BestTotalErrors ) |
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333 | { |
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334 | if ( BestClassifier ) ReleaseTree(BestClassifier); |
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335 | BestClassifier = Classifier; |
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336 | BestTotalErrors = TotalErrors; |
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337 | } |
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338 | else |
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339 | { |
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340 | ReleaseTree(Classifier); |
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341 | } |
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342 | |
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343 | /* Increment window size */ |
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344 | |
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345 | Additions = Min(Exceptions, IncExceptions); |
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346 | Window = Min(Window + Max(Additions, Exceptions / 2), MaxItem + 1); |
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347 | } |
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348 | while ( Exceptions ); |
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349 | |
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350 | return BestClassifier; |
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351 | } |
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352 | |
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353 | |
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354 | |
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355 | /*************************************************************************/ |
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356 | /* */ |
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357 | /* Print report of errors for each of the trials */ |
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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 | Evaluate(CMInfo, Saved) |
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363 | /* -------- */ |
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364 | Boolean CMInfo; |
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365 | short Saved; |
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366 | { |
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367 | ClassNo RealClass, PrunedClass, Category(); |
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368 | short t; |
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369 | ItemNo *ConfusionMat, i, RawErrors, PrunedErrors; |
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370 | |
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371 | if ( CMInfo ) |
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372 | { |
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373 | ConfusionMat = (ItemNo *) calloc((MaxClass+1)*(MaxClass+1), sizeof(ItemNo)); |
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374 | } |
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375 | |
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376 | printf("\n"); |
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377 | |
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378 | if ( TRIALS > 1 ) |
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379 | { |
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380 | printf("Trial\t Before Pruning After Pruning\n"); |
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381 | printf("-----\t---------------- ---------------------------\n"); |
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382 | } |
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383 | else |
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384 | { |
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385 | printf("\t Before Pruning After Pruning\n"); |
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386 | printf("\t---------------- ---------------------------\n"); |
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387 | } |
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388 | printf("\tSize Errors Size Errors Estimate\n\n"); |
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389 | |
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390 | ForEach(t, 0, TRIALS-1) |
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391 | { |
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392 | RawErrors = PrunedErrors = 0; |
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393 | |
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394 | ForEach(i, 0, MaxItem) |
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395 | { |
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396 | RealClass = Class(Item[i]); |
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397 | |
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398 | if ( Category(Item[i], Raw[t]) != RealClass ) RawErrors++; |
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399 | |
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400 | PrunedClass = Category(Item[i], Pruned[t]); |
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401 | |
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402 | if ( PrunedClass != RealClass ) PrunedErrors++; |
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403 | |
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404 | if ( CMInfo && t == Saved ) |
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405 | { |
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406 | ConfusionMat[RealClass*(MaxClass+1)+PrunedClass]++; |
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407 | } |
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408 | } |
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409 | |
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410 | if ( TRIALS > 1 ) |
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411 | { |
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412 | printf("%4d", t); |
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413 | } |
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414 | |
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415 | printf("\t%4d %3d(%4.1f%%) %4d %3d(%4.1f%%) (%4.1f%%)%s\n", |
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416 | TreeSize(Raw[t]), RawErrors, 100.0*RawErrors / (MaxItem+1.0), |
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417 | TreeSize(Pruned[t]), PrunedErrors, 100.0*PrunedErrors / (MaxItem+1.0), |
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418 | 100 * Pruned[t]->Errors / Pruned[t]->Items, |
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419 | ( t == Saved ? " <<" : "" )); |
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420 | } |
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421 | |
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422 | if ( CMInfo ) |
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423 | { |
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424 | PrintConfusionMatrix(ConfusionMat); |
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425 | free(ConfusionMat); |
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426 | } |
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427 | } |
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