Python High-order function--Sorted

For details, please refer to the official website of Liao Xuefeng, here are just a few excerpts, experience and practice of coding.

2. Python's built-in sorted() functions can sort the list:
   

   >>> sorted ([5, -12, 9, -21]) [-21,-12, 5, 9, 36]

4. sorted()A function is also a higher-order function, and it can also receive a key function to implement a custom sort, for example, by absolute size:
   

   >>> sorted ([5, -12, 9, -21], key=ABS) [5, 9,-12,-21, 36]

6. It is important to emphasize that sorted will only pass the elements of the first parameter list into the function specified by the key, not the entire list.
7. To reverse order, you do not have to change the key function, you can pass in the third argumentreverse=True：
   

   >>> Sorted (['Bob',' About','Zoo',' Credit'], Key=str.lower, reverse=True) ['Zoo',' Credit','Bob',' About']

9. sorted()the key to sorting is to implement a mapping function.
10. Practice
    1. Suppose we use a group of tuples to represent student names and scores:

       L = [(‘Bob‘, 75), (‘Adam‘, 92), (‘Bart‘, 66), (‘Lisa‘, 88)]

       Please sorted() sort the above list by name:

       # -*-coding:utf-8-*- L = [('Bob', '), ('Adam', "), ('Bart') ('Lisa', ")]def  by_name (t):     return  = sorted (L, key=by_name)print(L2)

    3. Then sort by grades from highest to lowest:
       

       # -*-coding:utf-8-*- L = [('Bob', '), ('Adam', "), ('Bart') ('Lisa', ")]def  By_score (t):     return t[1= sorted (L, key=by_score)print(L2)

Python High-order function--Sorted