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<?php
/**
* Piwik - free/libre analytics platform
*
* @link http://piwik.org
* @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
*
*/
namespace Piwik\DataTable\Filter;
use Piwik\DataTable;
use Piwik\DataTable\BaseFilter;
/**
* DataTable filter that will group {@link DataTable} rows together based on the results
* of a reduce function. Rows with the same reduce result will be summed and merged.
*
* _NOTE: This filter should never be queued, it must be applied directly on a {@link DataTable}._
*
* **Basic usage example**
*
* // group URLs by host
* $dataTable->filter('GroupBy', array('label', function ($labelUrl) {
* return parse_url($labelUrl, PHP_URL_HOST);
* }));
*
* @api
*/
class GroupBy extends BaseFilter
{
/**
* The name of the columns to reduce.
* @var string
*/
private $groupByColumn;
/**
* A callback that modifies the $groupByColumn of each row in some way. Rows with
* the same reduction result will be added together.
*/
private $reduceFunction;
/**
* Extra parameters to pass to the reduce function.
*/
private $parameters;
/**
* Constructor.
*
* @param DataTable $table The DataTable to filter.
* @param string $groupByColumn The column name to reduce.
* @param callable $reduceFunction The reduce function. This must alter the `$groupByColumn`
* columng in some way. If not set then the filter will group by the raw column value.
* @param array $parameters deprecated - use an [anonymous function](http://php.net/manual/en/functions.anonymous.php)
* instead.
*/
public function __construct($table, $groupByColumn, $reduceFunction = null, $parameters = array())
{
parent::__construct($table);
$this->groupByColumn = $groupByColumn;
$this->reduceFunction = $reduceFunction;
$this->parameters = $parameters;
}
/**
* See {@link GroupBy}.
*
* @param DataTable $table
*/
public function filter($table)
{
$groupByRows = array();
$nonGroupByRowIds = array();
foreach ($table->getRows() as $rowId => $row) {
// skip the summary row
if ($rowId == DataTable::ID_SUMMARY_ROW) {
continue;
}
$groupByColumnValue = $row->getColumn($this->groupByColumn);
$groupByValue = $groupByColumnValue;
// reduce the group by column of this row
if($this->reduceFunction) {
$parameters = array_merge(array($groupByColumnValue), $this->parameters);
$groupByValue = call_user_func_array($this->reduceFunction, $parameters);
}
if (!isset($groupByRows[$groupByValue])) {
// if we haven't encountered this group by value before, we mark this row as a
// row to keep, and change the group by column to the reduced value.
$groupByRows[$groupByValue] = $row;
$row->setColumn($this->groupByColumn, $groupByValue);
} else {
// if we have already encountered this group by value, we add this row to the
// row that will be kept, and mark this one for deletion
$groupByRows[$groupByValue]->sumRow($row, $copyMeta = true, $table->getMetadata(DataTable::COLUMN_AGGREGATION_OPS_METADATA_NAME));
$nonGroupByRowIds[] = $rowId;
}
}
// delete the unneeded rows.
$table->deleteRows($nonGroupByRowIds);
}
}
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