2-04列表类型

数据类型——列表

如何通过一个变量存储公司所有员工的名字？

列表是一个数据的集合，集合内可以放任何数据类型，可对集合进行方便的增删改查操作。

 

列表的功能：

• 创建

#方法一
L1 = [] #定义空列表
L2 = ['a','b','c','d'] #存4个值，索引为0-3
L3 =['abc',['def','ghi']] #嵌套列表

#方法二
L4 = list()

• 查询

• >>>
  >>> L2 = ['a','b','c','d','a','e',1,2]
  >>> L2[2] #通过索引取值                                                                                                                                                                                    
  'c'
  >>> L2[-1]#通过索引从列表右边开始取值                                                                                                                                                                              
  2
  >>> L2.index('a') #返回指定元素的索引值，从左向右查找，找到第一个匹配值                                                                                                                                                        
  0
  >>> L2.count('a') #统计指定元素的个数                                                                                                                                                                         
  2
  >>>

• 切片

• >>> L1 =['shanshan','longting','alex',1,34,4,5,6,9,2,1,1,5,8,8,10]                                                                                                                                    
  >>> L1[0:2]
  ['shanshan', 'longting']
  >>> L1[3:7]
  [1, 34, 4, 5]
  >>> L1[-5:-1] #切片只能从左向右切                                                                                                                                                                             
  [1, 5, 8, 8]
  >>> L1[-5:] #切片顾头不顾尾，要切到最后，就冒号后什么都不写                                                                                                                                                                  
  [1, 5, 8, 8, 10]
  >>> L1[:3]                                                                                                                                                                                            
  ['shanshan', 'longting', 'alex']
  >>> L1[:]
  ['shanshan', 'longting', 'alex', 1, 34, 4, 5, 6, 9, 2, 1, 1, 5, 8, 8, 10]
  >>> L1[:7:2]
  ['shanshan', 'alex', 34, 5]
  >>> L1[:7:3]
  ['shanshan', 1, 5]
  >>> L1[::2]
  ['shanshan', 'alex', 34, 5, 9, 1, 5, 8]

• 增加

• >>> n2 = ['shanshan','Longting','Alex',1,3,4,5,65,22,4,1,444,67]
  >>> n2.append('peiqi')
  >>> n2
  ['shanshan', 'Longting', 'Alex', 1, 3, 4, 5, 65, 22, 4, 1, 444, 67, 'peiqi']
  >>> n2.insert(0,'abc')
  >>> n2
  ['abc', 'shanshan', 'Longting', 'Alex', 1, 3, 4, 5, 65, 22, 4, 1, 444, 67, 'peiq
  i']
  >>> n2.insert(2,'James')
  >>> n2
  ['abc', 'shanshan', 'James', 'Longting', 'Alex', 1, 3, 4, 5, 65, 22, 4, 1, 444,
  67, 'peiqi']
  >>>

• 修改

• >>> n2
  ['abc', 'shanshan', 'James', 'Longting', 'Alex', 1, 3, 4, 5, 65, 22, 4, 1, 444,
  67, 'peiqi']
  >>> n2[2]='TTT'
  >>> n2
  ['abc', 'shanshan', 'TTT', 'Longting', 'Alex', 1, 3, 4, 5, 65, 22, 4, 1, 444, 67
  , 'peiqi']
  >>> n2[2:5]=['Jake','ti']
  >>> n2
  ['abc', 'shanshan', 'Jake', 'ti', 1, 3, 4, 5, 65, 22, 4, 1, 444, 67, 'peiqi']
  >>>

   

• 删除

• >>> n2 = ['shanshan','Longting','Alex',1,3,4,5,65,22,4,1,444,67]
  >>> n2.pop()
  67
  >>> n2
  ['shanshan', 'Longting', 'Alex', 1, 3, 4, 5, 65, 22, 4, 1, 444]
  >>> #pop是删除列表的最后一项，并返回这项的值
  >>> n2.remove(1)
  >>> n2
  ['shanshan', 'Longting', 'Alex', 3, 4, 5, 65, 22, 4, 1, 444]
  >>> del n2[2]
  >>> n2
  ['shanshan', 'Longting', 3, 4, 5, 65, 22, 4, 1, 444]
  >>> n2
  ['shanshan', 'Longting', 3, 4, 5, 65, 22, 4, 1, 444]
  >>> del n2[2:5]
  >>> n2
  ['shanshan', 'Longting', 65, 22, 4, 1, 444]

   

• 循环

• >>> for k in n2:
  ...     print('loop:',k)
  ...
  loop: shanshan
  loop: Longting
  loop: 65
  loop: 22
  loop: 4
  loop: 1
  loop: 444
  
  >>> for i in range(0,10):
  ...     print(i)
  ...
  0
  1
  2
  3
  4
  5
  6
  7
  8
  9

   

• 排序

• >>> n
  ['a', 'y', 'e', 'A', 'b', 'c', 'z']
  >>> n.sort()
  >>> n
  ['A', 'a', 'b', 'c', 'e', 'y', 'z']
  >>> n.reverse()
  >>> n
  ['z', 'y', 'e', 'c', 'b', 'a', 'A']

  列表拼接：

• >>> n2
  [1, 3, 4]
  >>> n
  ['z', 'y', 'e', 'c', 'b', 'a', 'A']
  >>> n2+n
  [1, 3, 4, 'z', 'y', 'e', 'c', 'b', 'a', 'A']
  >>> n2.extend(n)
  >>> n2
  [1, 3, 4, 'z', 'y', 'e', 'c', 'b', 'a', 'A']
  >>>

  清空列表

• >>> n2
  [1, 3, 4, 'z', 'y', 'e', 'c', 'b', 'a', 'A']
  >>>
  >>> n2.clear()
  >>> n2
  []

  copy

• >>> n=[1,2,4,7,2]
  >>> n
  [1, 2, 4, 7, 2]
  >>> n1=n.copy()
  >>> n1
  [1, 2, 4, 7, 2]
  >>> n.pop()
  2
  >>> n
  [1, 2, 4, 7]
  >>> n1
  [1, 2, 4, 7, 2]