Sphinx\SphinxClient::setGroupBy PHP Method

    public function setGroupBy($attribute, $func, $groupsort = '@group desc')
    {
        if (!is_string($attribute)) {
            throw new \InvalidArgumentException('Attribute name must be a string.');
        }
        if (!is_string($groupsort)) {
            throw new \InvalidArgumentException('Group sorting clause must be a string.');
        }
        if (!in_array($func, array(self::SPH_GROUPBY_DAY, self::SPH_GROUPBY_WEEK, self::SPH_GROUPBY_MONTH, self::SPH_GROUPBY_YEAR, self::SPH_GROUPBY_ATTR, self::SPH_GROUPBY_ATTRPAIR))) {
            throw new \InvalidArgumentException('Grouping function is invalid.');
        }
        $this->groupby = $attribute;
        $this->groupfunc = $func;
        $this->groupsort = $groupsort;
        return $this;
    }

 public function testUpdateAttributes()
 {
     $sphinx = new SphinxClient();
     $sphinx->setGroupBy('attr1', SphinxClient::SPH_GROUPBY_ATTR);
     $sphinx->updateAttributes('sphinxtest', array('attr1'), array(1 => array(10), 2 => array(10), 3 => array(20), 4 => array(20)));
     $results = $sphinx->query('bb');
     $this->assertEquals($results['total'], 3);
     // restore attributes
     $sphinx->updateAttributes('sphinxtest', array('attr1'), array(1 => array(2), 2 => array(4), 3 => array(1), 4 => array(5)));
 }