Python3 sorted() Function

Python3 内置函数Python3 Built-in Functions

Description

sorted()The function performs sorting operations on all iterable objects.

Difference between sort and sorted:

sort is a method applied to lists, while sorted can perform sorting operations on all iterable objects.

The list sort method operates on an existing list, while the built-in function sorted returns a new list, rather than operating on the original.

Syntax

sorted syntax:

sorted(iterable, key=None, reverse=False)

Parameter description:

  • iterable -- iterable object.
  • key -- mainly used to compare elements, has only one parameter. The specific function's parameter is taken from the iterable object, specifying an element in the iterable object to be used for sorting.
  • reverse -- sorting rule, reverse = True for descending order, reverse = False for ascending order (default).

Return Value

Returns a re-sorted list.

Example

The following example demonstrates the simplest usage of sorted:

>>> sorted([5, 2, 3, 1, 4])
[1, 2, 3, 4, 5]                      # default is ascending order

You can also use the list.sort() method of a list. This method modifies the original list (returns None). Usually this method is less convenient than sorted() - if you don't need the original list, list.sort() is slightly more efficient.

>>> a=[5,2,3,1,4]
>>> a.sort()
>>> a
[1,2,3,4,5]

Another difference is that the list.sort() method is only defined for lists, while the sorted() function can accept any iterable.

>>> sorted({1: 'D', 2: 'B', 3: 'B', 4: 'E', 5: 'A'})
[1, 2, 3, 4, 5]

Use key to sort in reverse order

>>> example_list = [5, 0, 6, 1, 2, 7, 3, 4]
>>> result_list = sorted(example_list, key=lambda x: x*-1)
>>> print(result_list)
[7, 6, 5, 4, 3, 2, 1, 0]
>>>

To sort in reverse order, you can also pass the third parameter reverse=True:

>>> example_list = [5, 0, 6, 1, 2, 7, 3, 4]
>>> sorted(example_list, reverse=True)
[7, 6, 5, 4, 3, 2, 1, 0]

The following is a more complex example, sorting the medal table. The data contains gold, silver, and bronze data for 15 countries, using\nas the delimiter:

Example

s = "Germany 10 11 16\nItaly 10 10 20\nNetherlands 10 12 14\nFrance 10 12 11\nUK 22 21 22\nChina 38 32 18\nJapan 27 14 17\nUSA 39 41 33\nRussian Olympic Committee 20 28 23\nAustralia 17 7 22\nHungary 6 7 7\nCanada 7 6 11\nCuba 7 3 5\nBrazil 7 6 8\nNew Zealand 7 6 7"
stodata = s.split('\n',-1)

# Use sorted
para = {}

for line in range(len(stodata)):
    # Each row of data
    data = stodata[line].split(' ')
    print(data)
    # Assemble the data structure para={'China': [], 'Russia': []}
    para[data[0]] = [int('-' + i) for i in data[1:]]
# Start sorting (x
new_para = sorted(para.items(), key=lambda x: (x[1], x[0]))
print()

c=[]
for i in new_para:
     c.append((i[0]))
for j in range(15):
    print(f"{(j+1):2d}  {c[j]}")

The output result is:

['德国', '10', '11', '16']
['意大利', '10', '10', '20']
['荷兰', '10', '12', '14']
['法国', '10', '12', '11']
['英国', '22', '21', '22']
['中国', '38', '32', '18']
['日本', '27', '14', '17']
['美国', '39', '41', '33']
['俄罗斯奥委会', '20', '28', '23']
['澳大利亚', '17', '7', '22']
['匈牙利', '6', '7', '7']
['加拿大', '7', '6', '11']
['古巴', '7', '3', '5']
['巴西', '7', '6', '8']
['新西兰', '7', '6', '7']

 1  美国
 2  中国
 3  日本
 4  英国
 5  俄罗斯奥委会
 6  澳大利亚
 7  荷兰
 8  法国
 9  德国
10  意大利
11  加拿大
12  巴西
13  新西兰
14  古巴
15  匈牙利

Python3 内置函数Python3 Built-in Functions

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