<?php
/**
 * Piwik - Open source web analytics
 * 
 * @link http://piwik.org
 * @license http://www.gnu.org/licenses/gpl-3.0.html Gpl v3 or later
 * @version $Id: ExcludeLowPopulation.php 519 2008-06-09 01:59:24Z matt $
 * 
 * @package Piwik_DataTable
 */

/**
 * Delete all rows that have a $columnToFilter value less than the $minimumValue 
 * 
 * For example we delete from the countries report table all countries that have less than 3 visits.
 * It is very useful to exclude noise from the reports.
 * You can obviously apply this filter on a percentaged column, eg. remove all countries with the column 'percent_visits' less than 0.05
 * 
 * @package Piwik_DataTable
 * @subpackage Piwik_DataTable_Filter 
 */
class Piwik_DataTable_Filter_ExcludeLowPopulation extends Piwik_DataTable_Filter
{
	static public $minimumValue;
	public function __construct( $table, $columnToFilter, $minimumValue )
	{
		parent::__construct($table);
		$this->columnToFilter = $columnToFilter;
		
		if($minimumValue == 0)
		{
			$minimumPercentageThreshold = 0.02;
			$allValues = $this->table->getColumn($this->columnToFilter);
			$sumValues = array_sum($allValues);
			$minimumValue = $sumValues * $minimumPercentageThreshold;
		}
		self::$minimumValue = $minimumValue;
		if(self::$minimumValue > 1)
		{
			$this->filter();
		}
	}
	
	function filter()
	{
		$filter = new Piwik_DataTable_Filter_ColumnCallbackDeleteRow(
												$this->table, 
												$this->columnToFilter, 
												array("Piwik_DataTable_Filter_ExcludeLowPopulation", "excludeLowPopulation")
											);
	}
	
	static public function excludeLowPopulation($value)
	{
		return $value >= self::$minimumValue;
	}
}

