I'm trying to compare things in list, tuple, etc. and I'm wondering how we specify what we want to compare. I want to sort a list: [('A',(6,2,1,3)), ('B',(4,5,9,3)), ('C',(1,2,3,8))] by the last number, and if the last number is equal, then sort by the 3rd number. However, I'm unsure how to approach this. I used lambda to sort by the last number, but when the last numbers are equal, python automatically sorts by the first number.
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2 Answers
Using the lambda, create a key which is a tuple of last number and third number:
mylist = [('B',(4,5,9,3)), ('C',(1,2,3,8)), ('A',(6,2,1,3))]
mylist.sort(key=lambda x:(x[1][-1], x[1][2]))
Outputs:
[('A', (6, 2, 1, 3)), ('B', (4, 5, 9, 3)), ('C', (1, 2, 3, 8))]
Comments
You basically want to sort by the last element in each tuple, reversed. Python translates that english to code pretty well:
sorted(li,key=lambda x: tuple(reversed(x[-1])))
Out[4]: [('A', (6, 2, 1, 3)), ('B', (4, 5, 9, 3)), ('C', (1, 2, 3, 8))]