What is sorted in python

sorted is a built-in function of Python and is not a unique method of mutable objects (lists and dictionaries). The sorted() function requires a parameter (the parameter can be a list, dictionary, tuple, or string), regardless of No matter what parameters are passed, a return value with a list as the container will be returned. If it is a dictionary, a list of keys will be returned.

list: (Recommended learning: Python video tutorial)

>>> a = [4,3,7,8]
>>> sorted(a)
[3, 4, 7, 8]
>>> a
[4, 3, 7, 8]

That is, sorted meeting Returns a copy of the list, and at the same time changes the value of the original list and assigns the returned value to other variables.

dict:

>>> b = {1:'ab',2:'degg',4:'ght',9:'d'}
>>> sorted(b)
[1, 2, 4, 9]
>>> b
{1: 'ab', 2: 'degg', 4: 'ght', 9: 'd'}

That is, when sorted(dict) is used, it is sorted by key and the key is returned as a list.

Or specify the conditions for sorting:

>>> b = {1:'ab',2:'degg',4:'ght',9:'d'}
>>> sorted(b.items(),key=lambda i:i[0])            #指定按字典里面的键排序
[(1, 'ab'), (2, 'degg'), (4, 'ght'), (9, 'd')]   
>>> 
>>> 
>>> sorted(b.items(),key=lambda i:len(i[1]))       #指定按字典里的value长度排序，默认从小到大
[(9, 'd'), (1, 'ab'), (4, 'ght'), (2, 'degg')]
>>> 
>>> 
>>> sorted(b.items(),key=lambda i:len(i[1]),reverse=True)   #指定按字典里的value长度排序，同时进行翻转，即按value的长度从大到小排列
[(2, 'degg'), (4, 'ght'), (1, 'ab'), (9, 'd')]

The process is: b.iterms() gets the [(key, value)] list of dictionary b. Through the key parameter, the sorting method is specified. Key ([0]) or value ([1]), reverse = True means that it needs to be flipped. The default is from small to large. If it is flipped, it will be from large to small.

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