我无法获取此代码来使用 .sort() 或sorted() 对对象列表进行排序。我在这里缺少什么?
附注如果有人有任何建议,我的solution.distance()方法也可以使用一些整容手术。
谢谢!
import random
import math
POPULATION_SIZE = 100
data = [[1, 565.0, 575.0],
[2, 25.0, 185.0],
[3, 345.0, 750.0],
[4, 945.0, 685.0],
[5, 845.0, 655.0],
[6, 880.0, 660.0],
[7, 25.0, 230.0],
[8, 525.0, 1000.0],
[9, 580.0, 1175.0],
[10, 650.0, 1130.0]
]
class Solution():
def __init__(self):
self.dna = []
self.randomize()
def randomize(self):
temp = data[:]
while len(temp) > 0:
self.dna.append( temp.pop( random.randint( 0,len(temp)-1 ) ) )
def distance(self):
total = 0
#There has to be a better way to access two adjacent elements.
for i, points in enumerate(self.dna):
if i < (len(self.dna)-1):
total += math.sqrt( (points[1]-self.dna[i+1][1])**2 + (points[2]-self.dna[i+1][2])**2 )
else:
total += math.sqrt( (points[1]-self.dna[0][1])**2 + (points[2]-self.dna[0][2])**2 )
return int(total)
class Population():
def __init__(self):
self.solutions = []
self.generation = 0
#Populate with solutions
self.solutions = [Solution() for i in range(POPULATION_SIZE)]
def __str__(self):
result = ''
#This is the part that is not returning sorted results. I tried sorted() too.
self.solutions.sort(key=lambda solution: solution.distance, reverse=True)
for solution in self.solutions:
result += 'ID: %s - Distance: %s\n' % ( id(solution), solution.distance() )
return result
if __name__ == '__main__':
p = Population()
print p
最佳答案
改变
key=lambda solution: solution.distance
至
key=lambda solution: solution.distance()
(调用该函数需要括号。)
或者,您可以将 distance
方法设为属性:
@property
def distance(self):
....
在这种情况下,将所有出现的 solution.distance()
更改为 solution.distance
。我认为这个替代解决方案更好一点,因为每次您想谈论距离时,它都会消除两个困惑的字符(括号)。
key=lambda 解决方案:solution.distance
为 self.solutions
中的每个 solution
返回绑定(bind)方法 solution.distance
>。由于相同的对象作为每个解决方案
的键返回,因此没有发生所需的排序。
关于python - 需要帮助按键对对象列表进行排序,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/3196112/