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python3 sort cmp问题
source link: https://cfonheart.github.io/2018/09/17/python3-sort-cmp%E9%97%AE%E9%A2%98/
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python3 sort cmp问题
根据自定义的数据结构进行排序, 希望按照能够像c/c++中的写法一样自定义cmp函数。
python2中是支持的，但是python3取消了cmp的关键字，可以通过functools.cmp_to_key达到同样的效果
demo样例如下:
from functools import cmp_to_key
import sys
class A:
def __init__(self, x, y):
self.x = x
self.y = y
def cmp_a(a, b):
if a.x < b.x or (a.x == b.x and a.y < b.y):
return -1
elif a.x == b.x and a.y == b.y:
return 0
else:
return 1
a_list = []
a_list.append(A(4, 5))
a_list.append(A(3, 5))
a_list.append(A(4, 3))
a_list.append(A(3, 4))
a_list.append(A(4, 4))
if sys.version_info[0] == 3:
a_list.sort(key=cmp_to_key(cmp_a))
# sorted(a_list, key=cmp_to_key(cmp_a)) # 上下两行功能一致
else:
a_list.sort(cmp=cmp_a)
for a in a_list:
print (a.x, a.y)
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