Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
1 | <?php |
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12 | class DecisionStump extends WeightedClassifier |
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13 | { |
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14 | use Trainable, Predictable; |
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15 | |||
16 | const AUTO_SELECT = -1; |
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17 | |||
18 | /** |
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19 | * @var int |
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20 | */ |
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21 | protected $givenColumnIndex; |
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22 | |||
23 | |||
24 | /** |
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25 | * Sample weights : If used the optimization on the decision value |
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26 | * will take these weights into account. If not given, all samples |
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27 | * will be weighed with the same value of 1 |
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28 | * |
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29 | * @var array |
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30 | */ |
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31 | protected $weights = null; |
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32 | |||
33 | /** |
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34 | * Lowest error rate obtained while training/optimizing the model |
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35 | * |
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36 | * @var float |
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37 | */ |
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38 | protected $trainingErrorRate; |
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39 | |||
40 | /** |
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41 | * @var int |
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42 | */ |
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43 | protected $column; |
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44 | |||
45 | /** |
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46 | * @var mixed |
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47 | */ |
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48 | protected $value; |
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49 | |||
50 | /** |
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51 | * @var string |
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52 | */ |
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53 | protected $operator; |
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54 | |||
55 | /** |
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56 | * @var array |
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57 | */ |
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58 | protected $columnTypes; |
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59 | |||
60 | /** |
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61 | * @var float |
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62 | */ |
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63 | protected $numSplitCount = 10.0; |
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64 | |||
65 | /** |
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66 | * A DecisionStump classifier is a one-level deep DecisionTree. It is generally |
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67 | * used with ensemble algorithms as in the weak classifier role. <br> |
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68 | * |
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69 | * If columnIndex is given, then the stump tries to produce a decision node |
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70 | * on this column, otherwise in cases given the value of -1, the stump itself |
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71 | * decides which column to take for the decision (Default DecisionTree behaviour) |
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72 | * |
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73 | * @param int $columnIndex |
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74 | */ |
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75 | public function __construct(int $columnIndex = self::AUTO_SELECT) |
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79 | |||
80 | /** |
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81 | * @param array $samples |
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82 | * @param array $targets |
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83 | */ |
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84 | public function train(array $samples, array $targets) |
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142 | |||
143 | /** |
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144 | * While finding best split point for a numerical valued column, |
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145 | * DecisionStump looks for equally distanced values between minimum and maximum |
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146 | * values in the column. Given <i>$count</i> value determines how many split |
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147 | * points to be probed. The more split counts, the better performance but |
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148 | * worse processing time (Default value is 10.0) |
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149 | * |
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150 | * @param float $count |
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151 | */ |
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152 | public function setNumericalSplitCount(float $count) |
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156 | |||
157 | /** |
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158 | * Determines best split point for the given column |
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159 | * |
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160 | * @param int $col |
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161 | * |
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162 | * @return array |
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163 | */ |
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164 | protected function getBestNumericalSplit(int $col) |
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196 | |||
197 | /** |
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198 | * |
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199 | * @param int $col |
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200 | * |
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201 | * @return array |
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202 | */ |
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203 | protected function getBestNominalSplit(int $col) |
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224 | |||
225 | |||
226 | /** |
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227 | * |
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228 | * @param type $leftValue |
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229 | * @param type $operator |
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230 | * @param type $rightValue |
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231 | * |
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232 | * @return boolean |
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233 | */ |
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234 | protected function evaluate($leftValue, $operator, $rightValue) |
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248 | |||
249 | /** |
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250 | * Calculates the ratio of wrong predictions based on the new threshold |
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251 | * value given as the parameter |
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252 | * |
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253 | * @param float $threshold |
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254 | * @param string $operator |
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255 | * @param array $values |
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256 | */ |
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257 | protected function calculateErrorRate(float $threshold, string $operator, array $values) |
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277 | |||
278 | /** |
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279 | * @param array $sample |
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280 | * @return mixed |
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281 | */ |
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282 | protected function predictSample(array $sample) |
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289 | |||
290 | public function __toString() |
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294 | } |
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295 |
In PHP it is possible to write to properties without declaring them. For example, the following is perfectly valid PHP code:
Generally, it is a good practice to explictly declare properties to avoid accidental typos and provide IDE auto-completion: