列表和元组

>>> shopping_list=[‘a‘,‘b‘,‘c‘,‘d‘,‘e‘,‘f‘]
>>> shopping
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name ‘shopping‘ is not defined
>>> shopping_list
[‘a‘, ‘b‘, ‘c‘, ‘d‘, ‘e‘, ‘f‘]

##切片
>>> len(shopping_list) #通过len()内置函数查找列表元素个数
6
>>> shopping_list[2] #第三个元素
‘c‘
>>> shopping_list[0] #第一个元素
‘a‘
>>> shopping_list[-1] #最后一个元素
‘f‘
>>> shopping_list[-3] #倒数第三位元素
‘d‘
>>> shopping_list[-4] #倒数第四个元素
‘c‘
>>> shopping_list[8]  #超出范围
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: list index out of range
>>> shopping_list[0:3] #取0到第三个元素，不包括第四个，0可以不写
[‘a‘, ‘b‘, ‘c‘]
>>> shopping_list[:3] #同上 
[‘a‘, ‘b‘, ‘c‘]
>>> shopping_list[2:5] #取第3至第5个元素
[‘c‘, ‘d‘, ‘e‘]
>>> shopping_list[:-3] #取从0至倒数第3个元素
[‘a‘, ‘b‘, ‘c‘]
>>> shopping_list[-3:] #取最后3个元素
[‘d‘, ‘e‘, ‘f‘]
>>> shopping_list[1:6:2] #1-6，每隔2个元素取1个
[‘b‘, ‘d‘, ‘f‘]
>>> shopping_list[::2]  #从头到尾每隔一个取一个
[‘a‘, ‘c‘, ‘e‘]


##增删改
>>> shopping_list.append(‘g‘) #向列表后面追加一个元素
>>> shopping_list
[‘a‘, ‘b‘, ‘c‘, ‘d‘, ‘e‘, ‘f‘, ‘g‘]
>>> shopping_list.pop() #删除最后一个元素
‘g‘
>>> shopping_list.remove(‘f‘) #删除叫”f“的元素，如果有多个f，那会从左边数找到的第一个
>>> shopping_list[2]
‘c‘
>>> shopping_list[2]=‘C‘ #将索引为2的元素改成”C“，原来是小写的！
>>> shopping_list
[‘a‘, ‘b‘, ‘C‘, ‘d‘, ‘e‘]
>>> shopping_list.insert(3,"haha") #插入一个新元素，索引为3
>>> shopping_list
[‘a‘, ‘b‘, ‘C‘, ‘haha‘, ‘d‘, ‘e‘]
>>> shopping_list.index(‘haha‘)  #返回‘haha’的索引值，如果有多个相同元素，则返回匹配的第一个
3
>>> shopping_list.append(‘haha‘) #再插多个进去
>>> shopping_list
[‘a‘, ‘b‘, ‘C‘, ‘haha‘, ‘d‘, ‘e‘, ‘haha‘]
>>> shopping_list.count(‘haha‘)  #统计‘haha’的元素个数
2
>>> list2=[‘h‘,‘i‘,‘j‘] #创建一个新列表
>>> shopping_list.extend(list2) #把上面的新列表合并到shopping_list
>>> shopping_list
[‘a‘, ‘b‘, ‘C‘, ‘haha‘, ‘d‘, ‘e‘, ‘haha‘, ‘h‘, ‘i‘, ‘j‘]
>>> shopping_list.sort() #将列表排序
>>> shopping_list
[‘C‘, ‘a‘, ‘b‘, ‘d‘, ‘e‘, ‘h‘, ‘haha‘, ‘haha‘, ‘i‘, ‘j‘]
>>> shopping_list.reverse() #将列表反转
>>> shopping_list
[‘j‘, ‘i‘, ‘haha‘, ‘haha‘, ‘h‘, ‘e‘, ‘d‘, ‘b‘, ‘a‘, ‘C‘]
>>> del shopping_list[3:8] #删除索引3至8的元素，不包括8
>>> shopping_list         
[‘j‘, ‘i‘, ‘haha‘, ‘a‘, ‘C‘]
>>> for i in shopping_list: #遍历列表
...   print i
... 
j
i
haha
a
C

>>> student=(‘yaobin‘,‘hy‘,‘nimei‘)
>>> student[0]
‘yaobin‘
>>> student[1]
‘hy‘
>>> student[1]=‘hyhy]‘  #不能修改
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: ‘tuple‘ object does not support item assignment
>>> t = (1,2)
>>> t
(1, 2)
>>> t = () #空元组
>>> t
()
>>> t = (1) #定义的不是元组了，是1这个数
>>> t
1
>>> t = (1,) #防止歧义，要加，
>>> t
(1,)          #这个才是元组