Sort the list in Python and keep the ID

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>>> a = [1,4,2,5,3]
>>> B = Sorted (Enumerate (a), key = Lambda x:x[1])
>>> b
[(0, 1), (2, 2), (4, 3), (1, 4), (3, 5)]
>>> B[1]
(2, 2)
>>> B[1][1]
2
>>> B[1][0]
2

About enumerate () How to use (copy)

Enumerate () description

• Enumerate () is a python built-in function
• Enumerate are enumerated and enumerated in the dictionary.
• For an iterative (iterable)/Ergodic object (such as a list, string), enumerate makes it an index sequence that can be used to obtain both the index and the value
• Enumerate multiple for counting in a for loop

• For example, for a seq, get:

  (0, seq[0]), (1, seq[1]), (2, seq[2])

• Enumerate () Returns a enumerate object, for example:
  

Enumerate () use

• If you want to traverse the index and iterate through the elements on a list, you can first write this:

list1 = ["这", "是", "一个", "测试"]for i in range (len(list1)): print i ,list1[i]

• 1
• 2
• 3

• The above method is somewhat cumbersome, and the use of enumerate () will be more direct and graceful:

list1 = ["这", "是", "一个", "测试"]for index, item in enumerate(list1): print index, item>>>0 这1 是2 一个3 测试

• Enumerate can also receive a second parameter that specifies the index starting value, such as:

list1 = ["这", "是", "一个", "测试"]for index, item in enumerate(list1, 1): print index, item>>>1 这2 是3 一个4 测试

Add

If you want to count the number of lines in a file, you can write:

‘r‘).readlines())

• 1

This method is simple, but may be slow, and cannot even work when the file is larger .

You can use enumerate ():

0for index, line in enumerate(open(filepath,‘r‘))：     count += 1

Sort the list in Python and keep the ID