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<?php |
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/** |
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* @author Boudewijn Schoon <[email protected]> |
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* @copyright Zicht Online <http://zicht.nl> |
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*/ |
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namespace Zicht\Itertools\lib\Traits; |
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use Zicht\Itertools as iter; |
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trait GroupByTrait |
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{ |
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/** |
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* Make an iterator that returns consecutive groups from this |
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* iterable. Generally, this iterable needs to already be sorted on |
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* the same key function. |
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* |
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* When $strategy is a string, the key is obtained through one of |
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* the following: |
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* 1. $value->{$strategy}, when $value is an object and |
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* $strategy is an existing property, |
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* 2. call $value->{$strategy}(), when $value is an object and |
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* $strategy is an existing method, |
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* 3. $value[$strategy], when $value is an array and $strategy |
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* is an existing key, |
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* 4. otherwise the key will default to null. |
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* |
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* Alternatively $strategy can be a closure. In this case the |
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* $strategy closure is called with each value in this iterable and the |
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* key will be its return value. $strategy is called with two |
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* parameters: the value and the key of the iterable as the first and |
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* second parameter, respectively. |
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* |
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* The operation of groupBy() is similar to the uniq filter in Unix. |
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* It generates a break or new group every time the value of the key |
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* function changes (which is why it is usually necessary to have |
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* sorted the data using the same key function). That behavior |
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* differs from SQL's GROUP BY which aggregates common elements |
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* regardless of their input order. |
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* |
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* > $list = [['type'=>'A', 'title'=>'one'], ['type'=>'A', 'title'=>'two'], ['type'=>'B', 'title'=>'three']] |
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* > iter\iterable($list)->groupBy('type') |
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* 'A'=>[['type'=>'A', 'title'=>'one'], ['type'=>'A', 'title'=>'two']] 'B'=>[['type'=>'B', 'title'=>'three']] |
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* |
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* @param null|string|\Closure $strategy |
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* @param bool $sort |
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* @return iter\lib\GroupbyIterator |
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*/ |
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public function groupBy($strategy, $sort = true) |
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{ |
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return iter\groupBy($strategy, $this, $sort); |
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} |
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} |
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zicht /
itertools
