On Saturday, October 15, 2016 at 12:27:42 AM UTC-7, Peter Otten wrote:
38016...@gmail.com wrote:
nums=['3','30','34','32','9','5']
I need to sort the list in order to get the largest number string: '953433230'
nums.sort(cmp=lambda a,b: cmp(a+b, b+a), reverse=True)
But how to do this in python 3?
Thank you
While cmp_to_key is neat doing it by hand should also be instructive. Essentially you move the comparison into a method of the key:
$ cat translate_cmp.py
class Key(str):
def __lt__(a, b):
return a + b < b + a
nums = ['3','30','34','32','9','5']
print(nums)
nums.sort(key=Key, reverse=True)
print(nums)
print("".join(nums))
$ python3 translate_cmp.py
['3', '30', '34', '32', '9', '5']
['9', '5', '34', '3', '32', '30']
953433230
The above works because in CPython list.sort() currently uses only the < operator; adding __gt__() and __eq__() to make this portable is straightforward even if you do not use the functools.total_ordering class decorator.
Is it possible to use lambda expression instead of defining a `Key` class? Something like `sorted(my_list, key = lambda x, y: x+y > y+x)`?
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