public function setAxisTicks($axis, array $ticks = array() )
    {
        if ( in_array($axis, array('x', 'y') ) ) {

            $isString = false;
            $alternateTicks = array();
            $cnt = 1;

            foreach ($ticks as $tick) {
                if (!(ctype_digit($tick) || is_int($tick))) {
                    $isString = true;
                    // this is O(2N) so deal with it
                    foreach ( $ticks as $tick ) {
                        $alternateTicks[] = array($cnt++, $tick);
                    }
                    break;
                }
            }
            
            $this->setNestedOptVal( $this->options, $axis.'axis', 'ticks', $isString ? $alternateTicks : $ticks );

        }

        return $this;
    }