列表相关操作

• 可获取,可修改,有序

• 列表的拼接 (同元组) +

  lst1 = [1,2,3]
  lst2 = [2,3,4]
  lst = lst1 + lst2
  print(lst)                           # [1, 2, 3, 2, 3, 4]
  

• 列表的重复 (同元组) *

  lst = lst1 * 3
  print(lst)                           # [1, 2, 3, 1, 2, 3, 1, 2, 3]
  
  tup = ("a","b")
  res = tup * 3
  print(res)
  

• 列表的切片 (同元组)

  语法 => 列表[::] 完整格式：[开始索引:结束索引:间隔值]

  lst = ["张治中","曹国晋","宋浩","欧阳郁郁","范李评","李文豪","申艳英","刘霞"]	
  (1)[开始索引:]                从开始索引截取到列表的最后
  print(lst[3:])
  
  (2)[:结束索引]                从开头截取到结束索引之前(结束索引-1)
  print(lst[:3])
  
  (3)[开始索引:结束索引]         从开始索引截取到结束索引之前(结束索引-1)
  print(lst[5:7])	
  print(lst[-3:-1])
  
  (4)[开始索引:结束索引:间隔值]  从开始索引截取到结束索引之前按照指定的间隔截取列表元素值
  print(lst[::2])                   #              从头->尾 间隔值为正
  print(lst[::-1])                  # -1 -2 -3 ... 从尾->头 间隔值为负
  
  (5)[:]或[::]  截取所有列表
  print(lst[:] , lst[::])
  

• 列表的获取 (同元组)

          0        1        2
  lst = ["张治中","曹国晋","宋浩"]
          -3       -2      -1
  print(lst[-1])
  

• 列表的修改 ( 可切片 )

  lst = ["张治中","曹国晋","宋浩","欧阳郁郁","范李评","李文豪","申艳英","刘霞"]	
    lst[1] = "曹国舅"                           # 修改一个数据
    print(lst)
  

  • 利用切片,一次修改多个数据

    iterable: 容器,range对象,迭代器
    lst[1:4] = ("张果老","吕洞宾","铁拐李","何仙姑")
    lst[1:4] =  1234                         # error 必须为Iterable类型才可以赋值
    lst[1:4] = "1234"
    print(lst)
    

  • 利用切片,切几个元素就修改几个元素

    lst = ["张治中","曹国晋","宋浩","欧阳郁郁","范李评","李文豪","申艳英","刘霞"]	
    print(lst[::3] )                        #0 3 6 9 12 .... 张治中 欧阳郁郁 申艳英
    
    lst[::3] = ["王源","王俊凯","易烊千玺"]
    lst[::3] = ["王源","王俊凯"]              # error
    
    print(lst)
    

  • 列表的删除 ( 可切片 )

    lst = ["张治中","曹国晋","宋浩","欧阳郁郁","范李评","李文豪","申艳英","刘霞"]	
    
    删除一个元素
      del lst[0]
      print(lst)
      
    删除多个元素
     del lst[0:3]                         # 0 1 2 
     print(lst)
    

    注意点1
    res = lst[0:3]                       # 删除是指向0:3这些元素的变量res本身,不是列表
    del res
    print(lst)
    
    注意点2
    tup = (1,2,3,[4,5])                  # 改变的是列表,不是元组
    tup[-1][-1] = 6
    print(tup)
    

  • 去掉列表所有重复元素

    常规写法一
    lst = ["a","b","a",3]
    res = set(lst)
    print( list(res) )                     # ["a","b","3"]
    

    按照次序来算
    append 从后面插入,追加
    lst = []
    lst.append(1)
    lst.append(2)
    lst.append(3)
    print(lst)                             # [1,2,3]
    

    进阶写法二  [保证次序]
    lst = ["a","b","a",3]
    lst_new = []
    for i in lst:                         # 不会你就for i in 先把数据跑起来
    	if i not in lst_new:              # 如果不在新列表里,就插入
    		lst_new.append(i)             # 插入
    print(lst_new)