《Python基础教程》学习笔记——序列

序列是Python中最基本的数据结构，序列中每个元素被分配一个序号——即元素的位置，也称索引，第一个索引是0，第二个索引是1，以此类推。 Python包括6中内建的序列：列表、元组、字符串、Unicode字符串、buffer对象和xrange对象。 下面介绍序列的基本通用操作：索引、切片、加、乘、成员资格、求最值和长度。

----------索引示例----------

根据给定的年月日以数字形式打印出日期

months = ['January','February','March','April','May','June',          'July','August','September','October','November','December'    ]# 以1~31的数字作为结尾的列表endings = ['st','nd','rd']+17*['th']\          +['st','nd','rd']+7*['th']\          +['st']year = raw_input('Year: ')month = raw_input('Month(1-12): ')day = raw_input('Day(1-31): ')month_number = int(month)day_number = int(day)# 记得要将月份和天数减去1，以获得正确的索引month_name = months[month_number-1]ordinal = day+endings[day_number-1]print month_name+ ' '+ordinal + ', '+year

----------切片示例----------

对“http://www.something.com”形式的URL进行分割

url = raw_input('Please enter the URL: ')domain = url[11:-4]print "Domain name: "+domain

其他的例子

numbers = [0,1,2,3,4,5,6,7,8,9]print numbers[:] #打印numbers中所有的值print numbers[0:3] #打印0,1,2print numbers[0::2] #等价于numbers[0:10:2]print numbers[0:10:2]print numbers[-10:-1] #等价于numbers[0:9]print numbers[-1:0:-1] #倒着打印

----------序列加、乘、成员资格、长度、最值----------

序列相加，主要只有两种相同类型的序列才能相加（即连接操作）

print [1,2,3]+[4,5,6] #结果为[1,2,3,4,5,6]print "hello,"+"world!"

用数字x乘以一个序列会生成新的序列，而在新的序列中，原来的序列将会被重复x次

print 'python'*5print [42]*10print [0]*10seq = [None]*10print seq

以正确的宽度在剧中的“盒子”内打印一个句子

sentence = raw_input("Secntence: ")screen_width = 80text_width = len(sentence)box_width = text_width + 6left_margin = (screen_width-box_width)//2printprint ' '*left_margin + '+'+'_'*(box_width-2)+'+'print ' '*left_margin+ '|'+' '*(box_width-2)+'|'print ' '*left_margin+'|'+' '*2+sentence+' '*2 +'|'print ' '*left_margin+ '|'+' '*(box_width-2)+'|'print ' '*left_margin + '+'+'_'*(box_width-2)+'+'print

用in运算符来检测一个值是否在序列中

permissions = 'rw'print 'w' in permissionsusers = ['mlh','foo','bar']print raw_input('Enter your user name: ') in userssubject = '$$$ Get rich now!!! $$$'print '$$$' in subject

序列成员资格示例

database = [    ['albert','1234'],    ['dilbert','4242'],    ['smith','7524'],    ['jones','9843']    ]username = raw_input('User name: ')pin = raw_input('PIN code: ')if [username,pin] in database:    print 'Access granted'

长度、最大值、最小值
内建函数 len、max、min

numbers1 = [100,34,678]print len(numbers1)print max(numbers1)print min(numbers1)