Python学习之：dictionary的注意事项

• 初始化dictionary

dict_1 = dict(red = 12, blue = 20, green = 14, grey = 10)
print(dict_1)

output:

{‘red’: 12, ‘blue’: 20, ‘green’: 14, ‘grey’: 10}

• dictionary的for循环

dict_1 = dict(red = 12, blue = 20, green = 14, grey = 10)
total = 0
for color in dict_1:
    print(color)
    print(type(color))
    total += dict_1[color]

print("the total num is:", total)

上面的循环变量color是字典dict_1中元素的索引，由输出的结果可知索引变量的类型

• dictionary的属性：keys(), values(）
  dictionary数据对象的属性keys（）可以展示出它的索引，values（）可以展示出所有的值。返回的类型分别是dict_keys和dict_values类型。

dict_1 = dict(red = 12, blue = 20, green = 14, grey = 10)
print(dict_1.keys())
print(type(dict_1.keys()))
print(dict_1.values())
print(type(dict_1.values()))

output：

注意：
生成的dict_keys和dict_values都是不可以像上面那种方式调用的