Python高效编程技巧实战(2)

开发环境:以Python2.x为主  IPython

第二天 : 02day

如何为元组中的每个元素命名，提高程序的可读性？
实际案列:学生信息系统中数据为固定格式:
(姓名,年龄,性别,邮箱,地址...)
学生数量很大为了减少存储开销,对每个学生信息用元组表示:
('Jim',18,'male','Jim123@qq.com')
('Lilei',20,'male','liLei456@163.com')
('Hangmeimei',19,'Hangmeimei@163.com')
......

访问时,我们使用引索(index)访问,大量引索降低程序的可读性,如何解决这个问题？

通常我们访问元组的方式如下:
In [38]: student = ('king',18,'male','38277946@qq.com')

In [39]: student[0]
Out[39]: 'king'

In [40]: student[2]
Out[40]: 'male'

In [41]: student[1]
Out[41]: 18

In [42]: student[3]
Out[42]: '38277946@qq.com'


解决方案:
方案1:
定义类似于其它语言的枚举类型,也就是定义一系列的数值常量
In [38]: student = ('king',18,'male','38277946@qq.com')

In [49]: NAME = 0

In [50]: AGE = 1

In [51]: SEX = 2

In [52]: EMAIL = 3

In [53]: student[NAME]
Out[53]: 'king'

In [54]: student[AGE]
Out[54]: 18

In [55]: student[SEX]
Out[55]: 'male'

In [56]: student[EMAIL]
Out[56]: '38277946@qq.com'

简化以上的操作方法:

In [62]: NAME,AGE,SEX,EMAIL = xrange(4)

In [63]: student[NAME]
Out[63]: 'king'

In [64]: student[AGE]
Out[64]: 18

In [65]: student[SEX]
Out[65]: 'male'

In [66]: student[EMAIL]
Out[66]: '38277946@qq.com'




方案2:
使用标准库中collections.namedtuple替代内置tuple

In [67]: from collections import namedtuple

In [68]: Student = namedtuple('Student',['name','age','sex','email'])      

In [69]: Student
Out[69]: __main__.Student

In [70]: s = Student('king',18,'male','38277946@qq.com')

In [71]: s.name
Out[71]: 'king'

In [72]: s.age
Out[72]: 18

In [73]: s.sex
Out[73]: 'male'

In [74]: s.email
Out[74]: '38277946@qq.com'

In [75]: isinstance(s,tuple)
Out[75]: True