SphinxClient::SetGroupBy PHP Method

    function SetGroupBy($attribute, $func, $groupsort = "@group desc")
    {
        assert(is_string($attribute));
        assert(is_string($groupsort));
        assert($func == SPH_GROUPBY_DAY || $func == SPH_GROUPBY_WEEK || $func == SPH_GROUPBY_MONTH || $func == SPH_GROUPBY_YEAR || $func == SPH_GROUPBY_ATTR || $func == SPH_GROUPBY_ATTRPAIR);
        $this->_groupby = $attribute;
        $this->_groupfunc = $func;
        $this->_groupsort = $groupsort;
    }

 protected function applyCriteria(ESphinxCriteria $criteria)
 {
     $this->applyMatchMode($criteria->matchMode);
     $this->applyRankMode($criteria->rankMode);
     $this->applySortMode($criteria->sortMode);
     // apply select
     if (strlen($criteria->select)) {
         $this->sphinxClient->SetSelect($criteria->select);
     }
     // apply limit
     if ($criteria->getIsLimited()) {
         $this->sphinxClient->SetLimits($criteria->offset, $criteria->limit, $criteria->max_matches, $criteria->cutoff);
     }
     // apply group
     if ($criteria->getIsGroupSetted()) {
         $this->sphinxClient->SetGroupBy($criteria->getGroupBy(), $criteria->getGroupFunc());
     }
     // apply id range
     if ($criteria->getIsIdRangeSetted()) {
         $this->sphinxClient->SetIDRange($criteria->getIdMin(), $criteria->getIdMax());
     }
     // apply weights
     $this->applyFieldWeights($criteria->getFieldWeights());
     $this->applyIndexWeights($criteria->getIndexWeights());
     // apply filters
     $this->applyFilters($criteria->getInConditions());
     $this->applyFilters($criteria->getNotInConditions(), true);
     // apply ranges
     $this->applyRanges($criteria->getInRanges());
     $this->applyRanges($criteria->getNotInRanges(), true);
 }