Python 如何按内部列表的特定索引对列表列表进行排序？
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How to sort a list of lists by a specific index of the inner list?
提问by oldspice
I have a list of lists. For example,
我有一份清单。例如，
[
[0,1,'f'],
[4,2,'t'],
[9,4,'afsd']
]
If I wanted to sort the outer list by the string field of the inner lists, how would you do that in python?
如果我想通过内部列表的字符串字段对外部列表进行排序，你会如何在 python 中做到这一点？
采纳答案by John La Rooy
This is a job for itemgetter
这是itemgetter的工作
>>> from operator import itemgetter
>>> L=[[0, 1, 'f'], [4, 2, 't'], [9, 4, 'afsd']]
>>> sorted(L, key=itemgetter(2))
[[9, 4, 'afsd'], [0, 1, 'f'], [4, 2, 't']]
It is also possible to use a lambda function here, however the lambda function is slower in this simple case
也可以在此处使用 lambda 函数，但是在这种简单情况下，lambda 函数会较慢
回答by mouad
in place
到位
>>> l = [[0, 1, 'f'], [4, 2, 't'], [9, 4, 'afsd']]
>>> l.sort(key=lambda x: x[2])
not in place using sorted:
没有使用排序：
>>> sorted(l, key=lambda x: x[2])
回答by Jim Brissom
Like this:
像这样：
import operator
l = [...]
sorted_list = sorted(l, key=operator.itemgetter(desired_item_index))
回答by fider
Itemgetter lets you to sort by multiple criteria / columns:
Itemgetter 允许您按多个条件/列进行排序：
sorted_list = sorted(list_to_sort, key=itemgetter(2,0,1))
回答by Rahul Kumar
multiple criteria can also be implemented through lambda function
也可以通过 lambda 函数实现多个条件
sorted_list = sorted(list_to_sort, key=lambda x: (x[1], x[0]))
回答by Tushar Niras
I think lambda function can solve your problem.
我认为 lambda 函数可以解决您的问题。
old_list = [[0,1,'f'], [4,2,'t'],[9,4,'afsd']]
#let's assume we want to sort lists by last value ( old_list[2] )
new_list = sorted(old_list, key=lambda x: x[2])
#Resulst of new_list will be:
[[9, 4, 'afsd'], [0, 1, 'f'], [4, 2, 't']]
回答by Abhishek Yadav
array.sort(key = lambda x:x[1])
You can easily sort using this snippet, where 1 is the index of the element.
您可以使用此代码段轻松排序，其中 1 是元素的索引。
回答by Maz1978
More easy to understand (What is Lambda actually doing):
更容易理解（Lambda 实际在做什么）：
ls2=[[0,1,'f'],[4,2,'t'],[9,4,'afsd']]
def thirdItem(ls):
#return the third item of the list
return ls[2]
#Sort according to what the thirdItem function return
ls2.sort(key=thirdItem)
回答by EgmontDeVos
**old_list = [[0,1,'f'], [4,2,'t'],[9,4,'afsd']]
#let's assume we want to sort lists by last value ( old_list[2] )
new_list = sorted(old_list, key=lambda x: x[2])**
correct me if i'm wrong but isnt the 'x[2]' calling the 3rd item in the list, not the 3rd item in the nested list? should it be x[2][2]?
如果我错了，请纠正我，但“x[2]”不是调用列表中的第 3 项，而不是调用嵌套列表中的第 3 项？应该是 x[2][2] 吗？
回答by Nishan
Sorting a Multidimensional Array execute here
排序多维数组在此处执行
arr=[[2,1],[1,2],[3,5],[4,5],[3,1],[5,2],[3,8],[1,9],[1,3]]
arr.sort(key=lambda x:x[0])
la=set([i[0] for i in Points])
for i in la:
tempres=list()
for j in arr:
if j[0]==i:
tempres.append(j[1])
for j in sorted(tempres,reverse=True):
print(i,j)
