Python 编程从入门到实践-chapter6

字典

一个简单的字典

alien = {'color': 'green', 'points': 6}

print(alien['color'])
print(alien['points'])

输出 green 6

使用字典

访问字典中的值

alien = {'color': 'green', 'points': 6}

new_points = alien['points']
print(new_points)

输出 6

添加键值对

alien = {'color': 'green', 'points': 6}

alien['x_position'] = 0
alien['y_position'] = 25
print(alien)

输出 {‘color’: ‘green’, ‘points’: 6, ‘x_position’: 0, ‘y_position’: 25}

从创建一个空字典开始

alien = {}

alien['x_position'] = 0
alien['y_position'] = 25
print(alien)

输出 {‘x_position’: 0, ‘y_position’: 25}

修改字典中的值

alien = {'color': 'green', 'points': 6}
alien['color'] = 'yellow'
print(alien)

输出 {‘color’: ‘green’, ‘points’: 6}

删除键值对

alien = {'color': 'green', 'points': 6}
del alien['color']
print(alien)

输出 {‘points’: 6}

使用 get() 方法访问值

alien = {'color': 'green', 'points': 6}
print(alien.get('color', 'No color value assigned.'))

输出 green

遍历字典

alien = {'color': 'green', 'points': 6}

for key, value in alien.items():
    print(f"\nKey: {key}")
    print(f"Value: {value}")

输出 Key: color Value: green

Key: points Value: 6

遍历字典中的所有键

alien = {'color': 'green', 'points': 6}

for key in alien.keys():
    print(f"\nKey: {key}")

输出 Key: color

Key: points

遍历字典中的所有值

alien = {'color': 'green', 'points': 6}

for value in alien.values():
    print(f"\nValue: {value}")

输出 Value: green

Value: 6

嵌套

字典列表

alien0 = {'color': 'green', 'points': 6}
alien1 = {'color': 'green', 'points': 6}

aliens = [alien0, alien1]

for alien in aliens:
    print(alien)

输出 {‘color’: ‘green’, ‘points’: 6} {‘color’: ‘green’, ‘points’: 6}

字典中存储列表

alien = {'color': 'green', 'points': 6，decorations: [1, 2, 3]}

字典中嵌套字典

alien = {'color': 'green', 'points': 6，decorations: {'weapen': 'gun', 'bult': 'big'}}

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字典