Python入门3-变量2
1.字典（使用花括号定义）
dairy_section = {}
dairy_section["breakfast"] = ("break","milk")
dairy_section["lunch"] = ("noodles","rices","dishes")
dairy_section["dinner"] = ("porridge","steamed bun")
读取时可以使用：
1）print(dairy_section)：显示全部的值
2）dairy_section.get("breakfast")：读取特定值
3）从字典中取键
print_keys = dairy_section.keys()
print_values = dairy_section.values(）
2.引用序列的最后一个元素（元组和列表均属于序列）
元组（列表）名称[-1],依次类推，比如week = ("Sunday","monday","Tuesday")
可使用print(week[-1])打印出"Tuesday"
3.将序列分片
1)将元组分片：例如workday = ("Monday","Tuesday","Wednesday","Thursday","Friday")
print(workday[0:2]),显示"Monday"，“Tuesday”
2)将列表分片：例如workday = ["Mondy","Tuesday","Wednesday","Thursday","Friday"]
print(workday[1:3]),显示"Tuesday","Wednesday"
3)将字符分片：例如workday = "from Monday to friday"
print(workday[2:5]),显示"om "
4.从列表中弹出元素
today_times = [2,5,3,6]
A = today_times.pop(0)
print(A),显示2,且print(today_times)时显示[5,3,6]
5.计算元组、列表或字典的长度
len(元组名或列表名或字典名)
6.处理集合
alphabet = ['a','b','b','c','d','e','e']
alph2 = set(alphabet)
print(alph2)显示{'a','b','c','d','e'}