l A simple dictionary
alien_0 = {'color': 'green','point': 5}
print(alien_0['color'])#使用大括号
The window will show green.
l Using dictionary
n Add key-value pair
For example,
alien_0 = {'color': 'green','point': 5}
print(alien_0['color'])
alien_0['x_position'] = 0
alien_0['y_position'] = 25
print(alien_0)
The window will show
{'color': 'green', 'point': 5, 'x_position': 0, 'y_position': 25}
-
Modify the key-value pair
alien_0['color'] = 'yellow'
-
Delete the key-value pair
Use del is OK.
For example,
del alien_0['points']
Dictionary will not include points.
-
Dictionary just like struct in C language.
-
The dictionary which consists of many objects:
For example,
favorite_languages = {
'David': 'python',
'Jane' : 'java',
'John' : 'C',
'Sarah' : 'ruby',
'Michel' : 'swift'
}
print("David's favorite languages is " +
favorite_languages['David'].title() + ".")
It will show,
David's favorite languages is Python.
Remember the format!
l Ergodic dictionary
n Ergodic all key-value pairs
Method: items(): items()方法用于返回字典dict的(key，value)元组对的列表
-
Ergodic all keys
Method: keys():返回字典dict的键列表
For example,
for name in favorite_languages.keys(): print(name.title() + ".") But if we use for name in favorite_languages: print(name.title() + ".")
They all have same output.
n Ergodic all values
n Method: values():返回字典dict的值列表
As we all know, the list of value may have same values, then ,how to keep only one value?
We can use set(). For example,
for language in set(favorite_languages.values()): print(language.title())
n Nesting: 将一系列字典存储在列表中，或将列表作为值存储在字典中，这被称为嵌套。
