Piwik\Plugins\CoreHome\Columns\UserId::isUsedInAtLeastOneSite PHP Method

    public function isUsedInAtLeastOneSite($idSites, $period, $date)
    {
        if ($period === 'day' || $period === 'week') {
            $period = 'month';
        }
        if ($period === 'range') {
            $period = 'day';
        }
        if (!empty($idSites)) {
            foreach ($idSites as $idSite) {
                if ($this->isUsedInSiteCached($idSite, $period, $date)) {
                    return true;
                }
            }
        }
        return false;
    }

 /**
  * @param DataTable $table
  */
 public function filter($table)
 {
     $userId = new UserId();
     if (!$userId->hasDataTableUsers($table) && !$userId->isUsedInAtLeastOneSite(array($this->idSite), $this->period, $this->date)) {
         $table->deleteColumn(Metrics::INDEX_NB_USERS);
     }
 }