2.1 序列概览 Python 包含6种内建的序列,本章重点讨论最常用的两种类型:列表和元组。列表和元组的主要区别在于,列表可以修改,元组则不能。edward=['a1','b2','c3']print edward[0];print edward[1];print edward[2];C:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a2.pya1b2c3修改序列的元素:edward=['a1','b2','c3']print edward[0];print edward[1];print edward[2];edward[0]='scan'print edwardC:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a2.pya1b2c3['scan', 'b2', 'c3']2.2 通用序列操作:注意 字符串就是一个由字符组成的序列,索引0指向第一个元素/*** \ 普通字符串也可以跨行,如果一行之中最后一个字符是反斜线,那么,换行符本身就是转义了,也就是被忽略了。print "Hello" \ "world"2.2.2 分片:numbers=[1,2,3,4,5,6,7,8,9,10]var=numbers[3:6]print varnumbers=[1,2,3,4,5,6,7,8,9,10]var=numbers[3:6]print vartag='Python web site'print tag[9:30]C:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a4.pyhttp://www.python.org下标从9到30from math import sqrtmonths = [ 'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']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,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: tag='Python web site'print tag[9:30]C:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a4.pyhttp://www.python.org从下边9到下标30,不包含30tag='Python web site'print tag[32:-4]C:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a4.pyPython web site32开始不包含-4简而言之,分片操作的实现需要提供两个索引作为边界,第一个索引的元素是包含在分片内的,而第2个则不包含在分片内。1. 优雅的捷径:假设需要访问最后3个元素(根据先前的例子),那么当然可以显示的操作:numbers=[1,2,3,4,5,6,7,8,9,10]print numbers[7:10]C:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a3.py[8, 9, 10]从索引8到索引10,索引10指向的是第11个元素,这个元素并不存在numbers=[1,2,3,4,5,6,7,8,9,10]print numbers[-3:-1]C:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a3.py[8, 9]-3 代表8-2 代表9-1 代表10numbers=[1,2,3,4,5,6,7,8,9,10]print numbers[-3]print numbers[-2]print numbers[-1]C:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a3.py89102.2.3 序列想加:numbers=[1,2,3,4,5,6,7,8,9,10]print [1,2,3] + [4,5,6]C:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a3.py[1, 2, 3, 4, 5, 6]简单的说,两种相同类型的序列才能进行连接操作；2.2.4 乘法:numbers=[1,2,3,4,5,6,7,8,9,10]print 'python'*5;C:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a3.pypythonpythonpythonpythonpython空列表可以简单地通过两个中括号进行表示[]----里面什么东西都没有.但是,如果想创建一个占用10个元素空间,确不包含任何有用内容的俩别哦,又该怎么办呢？2.2.5 成员资格:permisions='rw'if 'w' in permisions:print 'aaa';permisions = 'rw'if 'x' in permisions: print 'aaa'else:print 'bbbb'users=['a','b','c']if 'a' in users: print 'aaa'else:print 'bbbb'C:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a3.pyaaa2.2.6 长度,最小值和最大值numbers=[999,23,77]print len(numbers)print max(numbers)print min(numbers)C:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a5.py3999232.3 列表:Python 的"苦力"列表时可变的(mutable)---可以改变列表的内容,并且代表有很多有用的,专门的方法2.3.1 list 函数:va=list('hello')print vaC:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a5.py['h', 'e', 'l', 'l', 'o']va=list('12345689')print vaC:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a5.py['1', '2', '3', '4', '5', '6', '8', '9']2.3.2 基本的列表操作:1.改变列表: 元素赋值改变列表是很容易的,只需要使用在第一章提到的普通赋值语句即可。x=[1,2,3,4]print xx[1]=299print xC:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a5.py[1, 2, 3, 4][1, 299, 3, 4]x=[1,2,3,4]print xx[1]=299x[5]=300print xTraceback (most recent call last): File "C:/Users/Administrator/PycharmProjects/untitled1/a5.py", line 4, inx[5]=300IndexError: list assignment index out of range[1, 2, 3, 4]2.删除元素x=[1,2,3,4]print xdel x[1]print x删除元素3.分片赋值:分片是一个非常强大的特性,分片赋值操作则更加现实它的强大:name=list('perl')print nameC:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a5.py['p', 'e', 'r', 'l']name=list('perl')name[2:]=list('ar')print name替换元素:2.3.3 列表方法:perl中的方法调用:my $client=Client->new(); $client->get_qrcode();1.append方法用于在列表末尾追加新的对象:lst=[1,2,3]lst.append(4)print lstC:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a5.py[1, 2, 3, 4]2.countcount 方法统计某个元素在列表中出现的次数:3.extentd 方法可以在列表的末尾一次性追加另外一个序列中的多个值,换句话说,可以用新列表:a=[1,2,3]b=[4,5,6]print a.extend(b)print aC:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a5.pyNone[1, 2, 3, 4, 5, 6]4.index index 方法用于从列表中找出某个值第一个匹配项的索引位置:knights=['we','are','the','knights','who']print knights.index('who')数组越界:knights=['we','are','the','knights','who']print knights[99]Traceback (most recent call last): File "C:/Users/Administrator/PycharmProjects/untitled1/a4.py", line 2, in print knights[99]IndexError: list index out of range5.insert insert 方法用于将对象插入到列表中:numbers=[1,2,3,4,5,6,7]numbers.insert(3,'four')print numbersC:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a4.py[1, 2, 3, 'four', 4, 5, 6, 7]6. poppop 方法会移除列表中的一个元素(默认是最后一个),并且返回该元素的值x=[1,2,3,4,5,6,7]print x.pop();print xC:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a4.py7[1, 2, 3, 4, 5, 6]Process finished with exit code 07.添加元素:x=[1,2,3,4,5,6,7]print x.append(8)print x2.4 元组:不可变序列元组与列表一样,也是一种序列。唯一的不同是元组不能修改,创建元组的方法很简单,如果你用逗号分隔了一些值,那么你就自动创建了元组元组也是通过圆括号括起来的:>>> x=(42)>>> print x42>>> x=(42,)>>> print x(42,)x=(1,2,3,4)print x[1]x[1]=299print x元组不能修改：C:\Python27\python.exe C:/Users/Administrator/PycharmProjects/untitled1/a4.pyTraceback (most recent call last): File "C:/Users/Administrator/PycharmProjects/untitled1/a4.py", line 3, in x[1]=299TypeError: 'tuple' object does not support item assignment22.4.1 tuple 函数；2.4.2 基本元组操作2.4.1 tuple 函数