Two methods and examples of Python list sorting

to sort the list, Python provides two method methods 1. Sort by the list's built-in function List.sort List.sort (func=none, Key=none, reverse=False) Python instance:>>> list = [2,5,8,9,3]  >>>list [2,5,8,9,3]  >>>List.sort ()>>>list [2, 3, 5, 8, 9] Method 2: Sort the Python instance using the sequence type function sorted (list) (starting from 2.4).>>> list = [2,5,8,9,3]  >>>list [2,5,8,9,3]  >>>sorted (list) [2, 3, 5, 8, 9] The difference between the two methods: sorted (list) Returns an object that can be used as an expression. The original list does not change, creating a new sorted list object. List.sort () does not return an object, changing the original list. Other sort instances: Instance 1: Forward sort>>>l = [2,3,1,4]>>>L.sort ()>>>L>>>[1,2,3,4] Example 2: reverse sort>>>l = [2,3,1,4]>>>l.sort (reverse=True)>>>L>>>[4,3,2,1] Example 3: Sort the second keyword>>>l = [('b', 6), ('a', 1), ('C', 3), ('D', 4)]>>>l.sort (LambdaX,Y:CMP (x[1],y[1])) >>>L>>>[('a', 1), ('C', 3), ('D', 4), ('b', 6)] Example 4: Sort the second keyword>>>l = [('b', 6), ('a', 1), ('C', 3), ('D', 4)]>>>l.sort (key=LambdaX:x[1]) >>>L>>>[('a', 1), ('C', 3), ('D', 4), ('b', 6)] Example 5: Sort the second keyword>>>l = [('b', 2), ('a', 1), ('C', 3), ('D', 4)]>>>Importoperator>>>l.sort (Key=operator.itemgetter (1)) >>>L>>>[('a', 1), ('b', 2), ('C', 3), ('D', 4)] Example 6: (DSU method: Decorate-sort-undercorate)>>>l = [('b', 2), ('a', 1), ('C', 3), ('D', 4)]>>>a = [(x[1],i,x) forI,xinchEnumerate (L)]#I can confirm the stable sort>>>A.sort ()>>>l = [S[2] forSinchA]>>>L>>>[('a', 1), ('b', 2), ('C', 3), ('D', 4)] above gives a list of 6 of the method of sorting, where instance 3.4.5. 6 can play to sort an item in list item as the comparison keyword. Efficiency comparison: CMP< DSU <key by experimental comparison, Method 3 is slower than method 6, method 6 is slower than Method 4, Method 4 and Method 5 are basically quite a few keywords comparison sort: instance 7:>>>l = [('D', 2), ('a', 4), ('b', 3), ('C', 2)]>>> L.sort (key=LambdaX:x[1])>>>L>>>[('D', 2), ('C', 2), ('b', 3), ('a', 4] We see that this sort of L is sorted by the second keyword only, if we want to use the second keyword in order to sort the first keyword? There are two methods for instance 8:>>> L = [('D', 2), ('a', 4), ('b', 3), ('C', 2)]>>> L.sort (key=LambdaX: (x[1],x[0]))>>>L>>>[('C', 2), ('D', 2), ('b', 3), ('a', 4)] Example 9:>>> L = [('D', 2), ('a', 4), ('b', 3), ('C', 2)]>>> L.sort (Key=operator.itemgetter (1, 0))>>>L>>>[('C', 2), ('D', 2), ('b', 3), ('a', 4)] Why does instance 8 work? The reason is that a tuple is compared from left to right, compared to the first, if equal, compare the second

Two methods and examples of Python list sorting