列表的使用

列表是我们最以后最常用的数据类型之一，通过列表可以对数据实现最方便的存储、修改等操作

定义列表

1 >>> names = ["Zhangsan","Lisi","Wangwu","Zhaoliu"]

通过下标访问列表中的元素，下标从0开始计数

1 >>> names[0]
2 'Zhangsan'
3 >>> names[2]
4 'Wangwu'
5 >>> names[-1] #-1表示最后一位
6 'Zhaoliu'
7 >>> names[-2]
8 'Wangwu'

切片：

 1 >>> names = ["Zhangsan","Lisi","Wangwu","Zhaoliu","Qianqi","Sunba"]
 2 >>> names[1:4]  #取下标1至下标4之间的数字，包括1，不包括4(顾头不顾尾)
 3 ['Lisi', 'Wangwu', 'Zhaoliu']
 4 >>> names[1:-1] #取下标1至-1的值，不包括-1
 5 ['Lisi', 'Wangwu', 'Zhaoliu', 'Qianqi']
 6 >>> names[0:3] 
 7 ['Zhangsan', 'Lisi', 'Wangwu']
 8 >>> names[:3] #如果是从头开始取，0可以忽略，跟上句效果一样
 9 ['Zhangsan', 'Lisi', 'Wangwu']
10 >>> names[3:] #如果想取最后一个，必须不能写-1，只能这么写
11 ['Zhaoliu', 'Qianqi', 'Sunba']
12 >>> names[3:-1] #这样-1就不会被包含了
13 ['Zhaoliu', 'Qianqi']
14 >>> names[0::2] #后面的2是代表，每隔一个元素，就取一个
15 ['Zhangsan', 'Wangwu', 'Qianqi']
16 >>> names[::2] #和上句效果一样
17 ['Zhangsan', 'Wangwu', 'Qianqi']

追加：append

1 >>> names = ["Zhangsan","Lisi","Wangwu","Zhaoliu","Qianqi","Sunba"]
2 >>> names.append("我是新来的")
3 >>> names
4 ['Zhangsan', 'Lisi', 'Wangwu', 'Zhaoliu', 'Qianqi', 'Sunba', '我是新来的']

插入：insert

 1 >>> names
 2 ['Zhangsan', 'Lisi', 'Wangwu', 'Zhaoliu', 'Qianqi', 'Sunba', '我是新来的']
 3 >>>
 4 >>> names.insert(2,"从Wangwu前面插入")
 5 >>> names
 6 ['Zhangsan', 'Lisi', '从Wangwu前面插入', 'Wangwu', 'Zhaoliu', 'Qianqi', 'Sunba', '我是新来的']
 7 >>>
 8 >>> names.insert(5,"插入到Wangwu后面")
 9 >>> names
10 ['Zhangsan', 'Lisi', '从Wangwu前面插入', 'Wangwu', 'Zhaoliu', '插入到Wangwu后面', 'Qianqi', 'Sunba', '我是新来的']

修改：

1 >>> names
2 ['Zhangsan', 'Lisi', '从Wangwu前面插入', 'Wangwu', 'Zhaoliu', '插入到Wangwu后面', 'Qianqi', 'Sunba', '我是新来的']
3 >>> names[2] = "替补上场"
4 >>> names
5 ['Zhangsan', 'Lisi', '替补上场', 'Wangwu', 'Zhaoliu', '插入到Wangwu后面', 'Qianqi', 'Sunba', '我是新来的']

删除：del

 1 >>> del names[2] #删除指定下标
 2 >>> names
 3 ['Zhangsan', 'Lisi', 'Wangwu', 'Zhaoliu', '插入到Wangwu后面', 'Qianqi', 'Sunba', '我是新来的']
 4 >>> del names[4]
 5 >>> names.remove("Wangwu") #删除指定列表元素
 6 >>> names
 7 ['Zhangsan', 'Lisi', 'Zhaoliu', 'Qianqi', 'Sunba', '我是新来的']
 8 >>> names.pop()  #默认删除最后一位，添加下标后效果等同del names[x]
 9 '我是新来的'
10 >>> names
11 ['Zhangsan', 'Lisi', 'Zhaoliu', 'Qianqi', 'Sunba']

扩展：extend

1 >>> names
2 ['Zhangsan', 'Lisi', 'Zhaoliu', 'Qianqi', 'Sunba']
3 >>> names2 = [1,2,3,4]
4 >>> names.extend(names2)
5 >>> names
6 ['Zhangsan', 'Lisi', 'Zhaoliu', 'Qianqi', 'Sunba', 1, 2, 3, 4]

统计：count

1 >>> names = ["Zhangsan","Lisi"
,"Wangwu","Zhaoliu","Qianqi","Sunba","Wangwu"]
2 >>> names.count("Wangwu")
3 2

排序：sort

1 >>> names = ["!Zhangsan","123Lisi","$Wangwu","zhaoliu","Qianqi","Sunba"]
2 >>> names.sort()
3 >>> names
4 ['!Zhangsan', '$Wangwu', '123Lisi', 'Qianqi', 'Sunba', 'zhaoliu'] #按ASC码顺序排列

反转：reserse

1 >>> names
2 ['!Zhangsan', '$Wangwu', '123Lisi', 'Qianqi', 'Sunba', 'zhaoliu']
3 >>> names.reverse()
4 >>> names
5 ['zhaoliu', 'Sunba', 'Qianqi', '123Lisi', '$Wangwu', '!Zhangsan']

获取下标：index

1 >>> names
2 ['zhaoliu', 'Sunba', 'Qianqi', '123Lisi', '$Wangwu', '!Zhangsan']
3 >>>
4 >>> names.index("Qianqi")
5 2

清空: clear

1 >>> names
2 ['zhaoliu', 'Sunba', 'Qianqi', '123Lisi', '$Wangwu', '!Zhangsan']
3 >>> names.clear()
4 >>> names
5 []