Python sort and sorted function code parsing, pythonsorted

Python sort and sorted function code parsing, pythonsorted

This article focuses on the sort and sorted functions in Python.

I. sort Functions

The sort function is an internal function of the sequence.

Function prototype:

L.sort(cmp=None, key=None, reverse=False)

Function functions:

It sorts L in situ, that is, it does not return an ordered sequence copy, but changes the current sequence into an ordered sequence.

Parameter description:

(1) cmp Parameters

Cmp accepts a function and uses an integer as an example. The form is:

def f(a,b):   return a-b

If the elements to be sorted are of another type, if logic a is smaller than logic B, the function returns a negative number; logic a is equal to logic B, and function 0 is returned; logic a is greater than logic B, and function returns a positive number.

(2) key Parameters

The key also accepts a function. The difference is that this function only accepts one element, in the following form:

def f(a):   return len(a)

The Return Value of the function accepted by the key, indicating the weight of the element. The sort will sort the values according to the weight.

(3) reverse Parameters

Accept False or True to indicate whether to reverse

Example of sort:

(1) sort by element length

L = [{1:5,3:4},{1:3,6:3},{1:1,2:4,5:6},{1:9}]def f(x):  return len(x)sort(key=f)print L

Output:

[{1: 9}, {1: 5, 3: 4}, {1: 3, 6: 3}, {1: 1, 2: 4, 5: 6}]

(2) sort by the value of the element whose key is 1 in each dictionary element.

L = [{1:5,3:4},{1:3,6:3},{1:1,2:4,5:6},{1:9}]def f2(a,b):  return a[1]-b[1]L.sort(cmp=f2)print L

Output:

[{1: 1, 2: 4, 5: 6}, {1: 3, 6: 3}, {1: 5, 3: 4}, {1: 9}]

Ii. sorted Functions

The sorted function is a built-in function that accepts a sequence and returns an ordered copy.

The only difference between sort and sort is that a copy is returned.

Summary

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