失业程序员复习python笔记——字典和集合(2)

字典的增加，删除，更新等操作如下：

d = {'name': 'regina', 'age': 20}
d['gender'] = 'female' # 增加元素对'gender': 'female'
d['dat'] = '2025-04-11' # 增加元素对'dat': '2025-04-11'
print(d)
d['dat'] = '2025-04-10' # 更新元素对'dat': '2025-04-10'
print(d)
d.pop('dat') # 删除元素对'dat'
print(d)

D:\pyproject\venv\Scripts\python.exe D:/pyproject/py04.py

{'name': 'regina', 'age': 20, 'gender': 'female', 'dat': '2025-04-11'}

{'name': 'regina', 'age': 20, 'gender': 'female', 'dat': '2025-04-10'}

{'name': 'regina', 'age': 20, 'gender': 'female'}

Process finished with exit code 0

如果根据以上代码删除一个不存在的元素，就报如下错误

d.pop('dat1')
print(d)

D:\pyproject\venv\Scripts\python.exe D:/pyproject/py04.py

{'name': 'regina', 'age': 20, 'gender': 'female', 'dat': '2025-04-11'}

{'name': 'regina', 'age': 20, 'gender': 'female', 'dat': '2025-04-10'}

Traceback (most recent call last):

File "D:/pyproject/py04.py", line 7, in <module>

d.pop('dat1')

KeyError: 'dat1'

Process finished with exit code 1

集合增加，删除元素

s = {'regina',20}
s.add('female') # 增加元素female到集合
print(s)
s.remove('female') # 删除元素female
print(s)

D:\pyproject\venv\Scripts\python.exe D:/pyproject/py04.py

{'female', 20, 'regina'}

{20, 'regina'}

Process finished with exit code 0

字典根据键或值进行排序，代码如下

d = {'b': 1, 'a': 2, 'c': 10}
d_sorted_by_key = sorted(d.items(),key=lambda x:x[0]) # 根据字典键的升序排序
print(d_sorted_by_key)
d_sorted_by_value = sorted(d.items(),key=lambda x:x[1]) # 根据字典值的升序排序
print(d_sorted_by_value)

D:\pyproject\venv\Scripts\python.exe D:/pyproject/py04.py

[('a', 2), ('b', 1), ('c', 10)]

[('b', 1), ('a', 2), ('c', 10)]

Process finished with exit code 0

集合行排序的代码如下

s = {5,7,10,9,1,2}
print(sorted(s)) # 对集合的元素进行升序排序
print(sorted(s,reverse=True)) # 对集合的元素进行降序排序