摘要：列表嵌套列表，相当于其他语言中的二维数组列表的基本操作宫保鸡丁宫保鸡丁糖醋里脊粉丝蒸虾鱼香肉丝鱼香肉丝宫保鸡丁糖醋里脊粉丝蒸虾鱼香肉丝宫保鸡丁糖醋里脊宫保鸡丁糖醋里脊粉丝蒸虾鱼香肉丝鱼香肉丝宫保鸡丁糖醋里脊粉丝蒸虾鱼香肉丝鱼香肉丝宫保鸡
列表(list)
>>> type([1,2,3,4,5,6])
>>> type(["hello","worls",1,9])
>>> type(["hello","worls",1,9,True,False])
>>> type([[1,2],[3,4],[True,False]])//嵌套列表，相当于其他语言中的二维数组
列表的基本操作
"宫保鸡丁"
>>> ["宫保鸡丁","糖醋里脊","粉丝蒸虾","鱼香肉丝"][3]
"鱼香肉丝"
>>> ["宫保鸡丁","糖醋里脊","粉丝蒸虾","鱼香肉丝"][0:2]
["宫保鸡丁", "糖醋里脊"]
>>> ["宫保鸡丁","糖醋里脊","粉丝蒸虾","鱼香肉丝"][-1]
"鱼香肉丝"
>>> ["宫保鸡丁","糖醋里脊","粉丝蒸虾","鱼香肉丝"][-1:]
["鱼香肉丝"]
>>> ["宫保鸡丁","糖醋里脊","粉丝蒸虾","鱼香肉丝"]+["拍黄瓜","炒豆芽"]
["宫保鸡丁", "糖醋里脊", "粉丝蒸虾", "鱼香肉丝", "拍黄瓜", "炒豆芽"]
>>> ["拍黄瓜","炒豆芽"]*["拍黄瓜","炒豆芽"]
Traceback (most recent call last):
File "", line 1, in
["拍黄瓜","炒豆芽"]*["拍黄瓜","炒豆芽"]
TypeError: can"t multiply sequence by non-int of type "list"
>>> ["拍黄瓜","炒豆芽"]*3
["拍黄瓜", "炒豆芽", "拍黄瓜", "炒豆芽", "拍黄瓜", "炒豆芽"]
>>> ["拍黄瓜","炒豆芽"]-["拍黄瓜"]
Traceback (most recent call last):
File "", line 1, in
["拍黄瓜","炒豆芽"]-["拍黄瓜"]
TypeError: unsupported operand type(s) for -: "list" and "list"
元组(tuple)
>>> (1,2,3,4,5)
(1, 2, 3, 4, 5)
>>> (1,"-1",True)
(1, "-1", True)
>>> (1,2,3,4)[0]
1
>>> (1,2,3,4)[0:2]
(1, 2)
>>> (1,2,3)+(4,5,6)
(1, 2, 3, 4, 5, 6)
>>> (1,2,3)*3
(1, 2, 3, 1, 2, 3, 1, 2, 3)
>>> type((1,2,3))
>>> type(1)
>>> type([1,2,3])
>>> type("hello")
>>> type(("hello"))
>>> type((1))//如果括号里只有一个元素，python会默认为是要做数学运算，等同于type(1)
>>> (1+1)*2
4
>>> (1,2,3)
(1, 2, 3)
>>> (1)
1
>>> (1,)
(1,)
>>> type((1,))
>>> type(())
>>> type([1])
str list tuple都是序列
>>> "hello world"[2]
"l"
>>> [1,2,3][2]
3
>>> (1,2,3)[2]
3
切片
>>> [1,2,3,4,5][0:3]
[1, 2, 3]
>>> [1,2,3,4,5][-1:]
[5]
>>>
>>> "hello world"[0:8:0]
Traceback (most recent call last):
File "", line 1, in
"hello world"[0:8:0]
ValueError: slice step cannot be zero
>>> "hello world"[0:8:1]
"hello wo"
>>> "hello world"[0:8:2]
"hlow"
>>> "hello world"[0:8:3]
"hlw"
>>> "hello world"[0:8:4]
"ho"
>>> "hello world"[0:8:5]
"h "
>>> "hello world"[0:8:6]
"hw"
>>> "hello world"[0:8:7]
判断一个序列中是否包含某个元素
>>> 3 in [1,2,3,4,5,6]
True
>>> 7 in [1,2,3,4,5,6]
False
>>> 3 not in [1,2,3,4,5,6]
False
序列的其他操作
>>> len([1,2,3,4,5,6])
6
>>> len("hello world")
11
>>> max([1,2,3,4,5,6])
6
>>> min([1,2,3,4,5,6])
1
>>> max("hello world")
"w"
>>> min("hello world")
" "
>>> min("helloworld")
"d"
ASCII码
>>> ord("w")
119
>>> ord("d")
100
>>> ord(" ")
32
set 集合
集合的特性
>>> type({1,2,3,4,5,6})
>>> {1,2,3,4,5,6}[0] //集合是无序的，没有像str，list，tuple的架构索引,不能切片
Traceback (most recent call last):
File "", line 1, in
{1,2,3,4,5,6}[0]
TypeError: "set" object does not support indexing
>>> {1,2,3,4,5,6}[0:2]
Traceback (most recent call last):
File "", line 1, in
{1,2,3,4,5,6}[0:2]
TypeError: "set" object is not subscriptable
>>> {1,1,2,2,3,3,4,4} //集合的第二个特性：不重复
{1, 2, 3, 4}
集合的操作
>>> len({1,2,3})
3
>>> len({1,1,1})
1
>>> len({1,2,2})
2
>>> 1 in {1,2,3}
True
>>> 1 not in {1,2,3}
False
>>> {1,2,3,4,5,6} - {3,4} //求两个集合的差集
{1, 2, 5, 6}
>>> {1,2,3,4,5,6} & {3,4} //交集
{3, 4}
>>> {1,2,3,4,5,6} | {3,4,7} //合集|并集
{1, 2, 3, 4, 5, 6, 7}
//定义一个空的集合set()
>>> type({})
>>> type(set())
>>> len(set())
0
dict 字典
一个字典可以有很多个key和value，字典是一个集合类型，而不是序列
通过key 得到/访问 value
>>> {"menu1":"宫保鸡丁","menu2":"糖醋里脊","menu3":"粉丝蒸虾","menu4":"鱼香肉丝"}[0]
Traceback (most recent call last):
File "", line 1, in
{"menu1":"宫保鸡丁","menu2":"糖醋里脊","menu3":"粉丝蒸虾","menu4":"鱼香肉丝"}[0]
KeyError: 0
>>> {"menu1":"宫保鸡丁","menu2":"糖醋里脊","menu3":"粉丝蒸虾","menu4":"鱼香肉丝"}["menu1"]
"宫保鸡丁"
>>> {"menu1":"宫保鸡丁","menu1":"白斩鸡","menu2":"糖醋里脊","menu3":"粉丝蒸虾","menu4":"鱼香肉丝"}["menu1"]
"白斩鸡"
>>> {"menu1":"宫保鸡丁","menu1":"白斩鸡","menu2":"糖醋里脊","menu3":"粉丝蒸虾","menu4":"鱼香肉丝"}
{"menu1": "白斩鸡", "menu2": "糖醋里脊", "menu3": "粉丝蒸虾", "menu4": "鱼香肉丝"}
>>> {1:"宫保鸡丁","1":"白斩鸡","menu2":"糖醋里脊","menu3":"粉丝蒸虾","menu4":"鱼香肉丝"} //key也可以是数字
{1: "宫保鸡丁", "1": "白斩鸡", "menu2": "糖醋里脊", "menu3": "粉丝蒸虾", "menu4": "鱼香肉丝"}
value的类型可以是str | int | float | list | set | dict
>>> type({1:"宫保鸡丁","1":"白斩鸡","menu2":{1:1},"menu3":"粉丝蒸虾",})
key必须是不可变的类型(str、tuple)
>>> {[1,2]:"宫保鸡丁","menu2":"糖醋里脊","menu3":"粉丝蒸虾","menu4":"鱼香肉丝"}
Traceback (most recent call last):
File "", line 1, in
{[1,2]:"宫保鸡丁","menu2":"糖醋里脊","menu3":"粉丝蒸虾","menu4":"鱼香肉丝"}
TypeError: unhashable type: "list"
>>> {(1,2):"宫保鸡丁","menu2":"糖醋里脊","menu3":"粉丝蒸虾","menu4":"鱼香肉丝"}
{(1, 2): "宫保鸡丁", "menu2": "糖醋里脊", "menu3": "粉丝蒸虾", "menu4": "鱼香肉丝"}
