第六章 字典

6.2 使用字典

在Python中，字典是一系列键值对,任何Python对象都可用作字典的值
Pyhone字典用花括号{}表示

# encoding=utf-8
alien_0 = {'color': 'green', 'age': 18}
print(alien_0['color'])
print(alien_0['age'])

alien_0['age'] = alien_0['age'] + 1
# 添加键值对
alien_0['x_position'] = 0
alien_0['y_position'] = 180
print(alien_0)

alien_1 = {}
alien_1['color'] = 'red'
alien_1['age'] = 20
alien_1['x_position'] = 10
alien_1['y_position'] = 80
print(alien_1)

# 删除键
alien_0['test'] = 'test'
print('delete before:' + str(alien_0))
del alien_0['test']
print('delete after:' + str(alien_0))

dic_favorite_laguages = {
    'zhang': 'java',
    'wang': 'C',
    'li': 'C++',
    'zhao': 'Python',
    'shi': 'java',
}
print(dic_favorite_laguages)

# 字典遍历:注意遍历时键值对返回顺序与存储顺序不同
print('------=======--------')
for key, value in dic_favorite_laguages.items():
    print(key + ":" + str(value))
print('------=======--------')
for key in dic_favorite_laguages.keys():
    print(key)
print('------=======--------')
for value in dic_favorite_laguages.values():
    print(str(value))
person_name = 'qian'
if person_name not in dic_favorite_laguages.keys():
    print(person_name + 'not select favorite laguages')

# 按照指定顺序遍历字典
print('------=======--------')
for key in sorted(dic_favorite_laguages.keys()):
    print(key + ":" + dic_favorite_laguages[key])
print('------=======--------')

# set()去除重复项
for value in set(dic_favorite_laguages.values()):
    print(str(value))

# 各种嵌套
aliens = [alien_0, alien_1]
print('------=======--------')
for alien in aliens:
    print(alien)
aliens = []
for number in range(10):
    alien = {'color': 'red', 'age': 18, 'x_position': 20, 'y_position': 40}
    aliens.append(alien)
for alien in aliens[:3]:
    alien['color'] = 'blue'
print('------=======--------')
for alien in aliens[:5]:
    print(alien)

/usr/local/bin/python3.7 /Users/chujun/PycharmProjects/ahs/python_start_and_practice/first/six_chapter/alien.py
green
18
{'color': 'green', 'age': 19, 'x_position': 0, 'y_position': 180}
{'color': 'red', 'age': 20, 'x_position': 10, 'y_position': 80}
delete before:{'color': 'green', 'age': 19, 'x_position': 0, 'y_position': 180, 'test': 'test'}
delete after:{'color': 'green', 'age': 19, 'x_position': 0, 'y_position': 180}
{'zhang': 'java', 'wang': 'C', 'li': 'C++', 'zhao': 'Python', 'shi': 'java'}
------=======--------
zhang:java
wang:C
li:C++
zhao:Python
shi:java
------=======--------
zhang
wang
li
zhao
shi
------=======--------
java
C
C++
Python
java
qiannot select favorite laguages
------=======--------
li:C++
shi:java
wang:C
zhang:java
zhao:Python
------=======--------
Python
C
C++
java
------=======--------
{'color': 'green', 'age': 19, 'x_position': 0, 'y_position': 180}
{'color': 'red', 'age': 20, 'x_position': 10, 'y_position': 80}
------=======--------
{'color': 'blue', 'age': 18, 'x_position': 20, 'y_position': 40}
{'color': 'blue', 'age': 18, 'x_position': 20, 'y_position': 40}
{'color': 'blue', 'age': 18, 'x_position': 20, 'y_position': 40}
{'color': 'red', 'age': 18, 'x_position': 20, 'y_position': 40}
{'color': 'red', 'age': 18, 'x_position': 20, 'y_position': 40}

Process finished with exit code 0