(1)索引
str1='Hello' nums=[1,2,3,4] t1=(123,234,345) print str1[0] print nums[1] print t1[2]
输出
H 2 345
索引从0(从左向右)开始,所有序列可通过这种方式进行索引。神奇的是,索引可以从最后一个位置(从右向左)开始,编号是-1:
str1='Hello' nums=[1,2,3,4] t1=(123,234,345) print str1[-1] print nums[-2] print t1[-3]
输出:
o 3 123
(2)分片
分片操作用来访问一定范围内的元素。分片通过冒号相隔的两个索引来实现:
nums=range(10) print nums print nums[1:5] print nums[6:10] print nums[1:] print nums[-3:-1] print nums[-3:] #包括序列结尾的元素,置空最后一个索引 print nums[:] #复制整个序列
输出:
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9] [1, 2, 3, 4] [6, 7, 8, 9] [1, 2, 3, 4, 5, 6, 7, 8, 9] [7, 8] [7, 8, 9]
不同的步长,有不同的输出:
nums=range(10) print nums print nums[0:10] #默认步长为1 等价于nums[1:5:1] print nums[0:10:2] #步长为2 print nums[0:10:3] #步长为3 ##print nums[0:10:0] #步长为0 print nums[0:10:-2] #步长为-2
输出:
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9] [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] [0, 2, 4, 6, 8] [0, 3, 6, 9] []
(3)序列相加
str1='Hello' str2=' world' print str1+str2 num1=[1,2,3] num2=[2,3,4] print num1+num2 print str1+num1
输出:
Hello world [1, 2, 3, 2, 3, 4]
Traceback (most recent call last):
File "F:Pythontest.py", line 7, in <module>
print str1+num1
TypeError: cannot concatenate 'str' and 'list' objects
(4)乘法
print [None]*10 str1='Hello' print str1*2 num1=[1,2] print num1*2 print str1*num1
输出:
[None, None, None, None, None, None, None, None, None, None] HelloHello [1, 2, 1, 2]
Traceback (most recent call last):
File "F:Pythontest.py", line 5, in <module>
print str1*num1
TypeError: can't multiply sequence by non-int of type 'list'
(5)成员资格
in运算符会用来检查一个对象是否为某个序列(或者其他类型)的成员(即元素):
str1='Hello' print 'h' in str1 print 'H' in str1 num1=[1,2] print 1 in num1
输出:
False True True
(6)长度、最大最小值
通过内建函数len、max和min可以返回序列中所包含元素的数量、最大和最小元素。
str1='Hello' print len(str1) print max(str1) print min(str1) num1=[1,2,1,4,123] print len(num1) print max(num1) print min(num1)










