我想用Python计算线段的长度(任意数量)。我使用了下面的代码，但是我遇到元组不能将减法作为操作数。我怎样才能克服呢？我想知道我是否错过了任何重要的Python概念。在from itertools import starmap
import math
class Point(object):
def __init__(self,x,y):
self.x=x
self.y=y
def move(self,dx,dy):
self.x+=dx
self.y+=dy
class LineString(object):
def __init__(self,*args): # A method with any number of arguments, args
self.args=[Point(*args) for p in args] # A list of Points
def length(self):
pairs=zip(self.args, self.args[1:])
return sum(starmap(distance,pairs))
def distance(p1, p2):
a = p1.x,p1.y
b = p2.x,p2.y
print (math.sqrt((a[0]-b[0])**2-(a[1]-b[1])**2))
# calculates distance between two given points p1 and p2
return math.sqrt((a** 2)+ (b** 2))
if __name__ == '__main__':
# Tests for LineString
# ===================================
lin1 = LineString((1, 1), (0, 2))
assert lin1.length() == sqrt(2.0)
lin1.move(-1, -1) # Move by -1 and -1 for x and y respectively
assert lin1[0].y == 0 # Inspect the y value of the start point.
# Implement this by overloading __getitem__(self, key) in your class.
lin2 = LineString((1, 1), (1, 2), (2, 2))
assert lin2.length() == 2.0
lin2.move(-1, -1) # Move by -1 and -1 for x and y respectively
assert lin2.length() == 2.0
assert lin2[-1].x == 1 # Inspect the x value of the end point.
print ('Success! Line tests passed!')