public function getColourByIndex($index=0) {
    	if (isset($this->_colourMap[$index])) {
			return $this->_colourMap[$index];
		}
		return null;
    }
public function getColourByIndex($index=0) {
    	if (isset($this->_colourMap[$index])) {
			return $this->_colourMap[$index];
		}
		return null;
    }
public function getColourByIndex ( $ index = 0 ) { if ( isset ( $ this -> _colourMap [ $ index ] ) ) { return $ this -> _colourMap [ $ index ] ; } return null ; }
Get colour Map Value by Position

@return string
Get colour Map Value by Position