def __make_data_index(self, line):
		if(line.startswith("#")):
			self.offset += 1
		else:
			try:
				token = line.split()
				# make a tuple (x, y, index)
				entry = (float(token[1]), float(token[2]), int(token[0]))
				self.data_index.append(entry)
			except IndexError:
				pass