你必须排序两次。 Python的排序算法是stable,这意味着相等的元素保持其相对顺序。使用它首先对第二个元素进行排序(按升序排序),然后仅对第一个元素按相反顺序再次对输出进行排序:
sorted(sorted(my_list2, key=lambda t: t[1]), key=lambda t: t[0], reverse=True)
Using operator.itemgetter() https://docs.python.org/3/library/operator.html#operator.itemgetter代替lambda
s 可以让这个过程更快一些(避免为每个元素返回到 Python 解释器):
from operator import itemgetter
sorted(sorted(my_list2, key=itemgetter(1)), key=itemgetter(0), reverse=True)
Demo:
>>> from operator import itemgetter
>>> my_list2 = [('aaa', 'bbb'), ('aaa', 'ccc'), ('bbb', 'aaa'), ('bbb', 'ccc')]
>>> sorted(sorted(my_list2, key=lambda t: t[1]), key=lambda t: t[0], reverse=True)
[('bbb', 'aaa'), ('bbb', 'ccc'), ('aaa', 'bbb'), ('aaa', 'ccc')]
>>> sorted(sorted(my_list2, key=itemgetter(1)), key=itemgetter(0), reverse=True)
[('bbb', 'aaa'), ('bbb', 'ccc'), ('aaa', 'bbb'), ('aaa', 'ccc')]
一般规则是从最里面的元素到最外面的元素排序。因此,对于任意元素计数排序,每个都有一个键和一个反向布尔值,您可以使用functools.reduce()功能 https://docs.python.org/3/library/functools.html#functools.reduce应用这些:
from functools import reduce
from operator import itemgetter
def sort_multiple(sequence, *sort_order):
"""Sort a sequence by multiple criteria.
Accepts a sequence and 0 or more (key, reverse) tuples, where
the key is a callable used to extract the value to sort on
from the input sequence, and reverse is a boolean dictating if
this value is sorted in ascending or descending order.
"""
return reduce(
lambda s, order: sorted(s, key=order[0], reverse=order[1]),
reversed(sort_order),
sequence
)
sort_multiple(my_list2, (itemgetter(0), True), (itemgetter(1), False))