（十）列表的增删改查

增
删
改
查

1.定义一个列表:names= []--------------------------------------------空列表
2.查看列表数据类型:-------------------------------------------------type(names)>>(class'list')
3.【存】往列表里放东西:names =['Alex','Tenglan','Eric','gaojun']>>print (name)>>['Alex','Tenlan','Eric','gaojun]
4.【取】用索引取数据:>>names[0]>>'Alex' names[2]>>'Eric'    >>names[-1]>>'gaojun'
>>names[-2]>>'Eric'--------------------------------------------------可以倒着取
5.【切片】取多个元素:names=['Alex','Tenlan','Eric','Rain','Tom','Amy','gaojun']
 5.1>>naems[1:4]>>['Alex','Tenlan','Eric',]---------------------------取下标是1至4之间的数字在,包括1,不包括4,顾头不顾尾原则
 5.2>>names[1:-1]>>['Alex','Tenlan','Eric','Rain','Tom','Amy']--------取下标1至-1的值，不包括-1，顾头不顾尾原则.
 5.3>>names[0:3]>>['Alex','Tenlan','Eric',]---------------------------从头到3的值，不包括3，顾头不顾尾.
 5.4>>names[:3]>>['Alex','Tenlan','Eric',]----------------------------从头到3的值，不包括3，开头的0可以忽略.
 5.5>>names[3:]>>['Rain','Tom','Amy','gaojun']------------------------如果想去最后一个值，必须不能取-1.
 5.6>>names[3:-1]>>['Rain','Tom','Amy']-------------------------------这样-1就不会被包括了.
 5.7>>names[0::2]>>['Alex','Rric,'Tom','gaojun']----------------------后面2是步长，每隔一个元素，开始取值，即第二步取值.
 5.8>>names[::2]>>['Alex','Rric,'Tom','gaojun']------------------------和上面效果一样.
6.【追加】append()
  6.1 names=['Alex','Eric']>>>names.append("gaojun")>>>['Alex','Eric','gaojun']
7.【插入】insert()---------- names = ['Alex','Erix','goajun']
  7.1把gaojun2强行插入到Eric前面：names.insert(1,"gaojun2")>>print (names) >>['Alex','gaojun2','Eric','gaojun']
  7.2把gaojun3强行插入到Eric后面：names.insert(4,'gaojun3')>>print(names)>>>['Alex','gaojun2','Eric','gaojun3','gaojun']
8.【修改】--[]
  8.1 names =['Alex','Eric','gaojun']>>> names[2] = "lisi">>>print(names)>>>['Alex','Eric','lisi']
9.【删除】3种方法------------(1)del(2)remove(3)pop
  9.1 names = ['Alex','Tenlan','Eric','Rain','Tom','Amy','gaojun']>>del[2]>>['Alex','Tenlan','Rain','Tom','Amy','gaojun']
  9.2 names = ['Alex','Tenlan','Rain','Tom','Amy','gaojun']>>del[4]>>['Alex','Tenlan','Rain','Tom','gaojun']
  9.3 删除指定元素：remove>>>names =['Alex','Tenlan','Rain','Tom','gaojun']>>>names.remove("Tenlan")>>>['Alex','Rain','Tom','gaojun']
  9.4 删除列表最后一个值：pop>>>['Alex','Rain','Tom','gaojun']>>>names.pop()>>>print(names)>>>['Alex','Rain','Tom','gaojun']
10.【拓展】extend()----------------extend后面的元素也是列表
  10.1 names=['Alex','Rain','Tom','gaojun'] b=[1,2,3,4] >>>names.expend(b)>>>print (names)>>>['Alex','Rain','Tom','gaojun',1,2,3,4]--?
11【拷贝】copy()
  11.1 names = ['Alex','Rain','Tom','gaojun']>>>name_copy = names.copy()>>>print(name_copy)>>>['Alex','Rain','Tom','gaojun']
12.【统计】count（）
  12.1 names = ['Alex','Rain','Tom','gaojun','gaojun','gaojun1',1,2,3,4]>>>print(names.count("gaojun"))>>2
13.【排序&翻转】(1)names.sort(2)names.revers()
  13.1 names = ['Alex','Tenlan','Eric','Rain','Tom','Amy','gaojun',1,2,3,4]>>>names.sort()>>>看看结果如何?
  13.2 names = ['Alex','Tenlan','Eric','Rain','Tom','Amy','gaojun','1','2','3','4']>>>names.sort()>>>看看结果如何?--
       ['1', '2', '3', '4', 'Alex', 'Amy', 'Eric', 'Rain', 'Tenlan', 'Tom', 'gaojun']
  13.3  names.revers>>>['gaojun', 'Tom', 'Tenlan', 'Rain', 'Eric', 'Amy', 'Alex', '4', '3', '2', '1']
14.【获取下标】index()
  14.1 names=['Alex','gaojun2','Eric','gaojun','gaojun']>>>names.index('gaojun')>>>3-------------只会返回一个下标,从左到右检索,找到即返回.