字典：
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#可以用大括号创建字典，也可以用工厂函数创建；cleese={}
palin=dict()
#给字典加入一些数据cleese['Name'] = 'John Cleese'
cleese['Occupations'] = ['actor','comedian','writer',]
#查看里面有哪些数据项In [9]: cleese
Out[9]: {'Name': 'John Cleese', 'Occupations': ['actor', 'comedian', 'writer']}
palin = {'Name':'Michael Palin','Occupations':['comedian','actor','writer','tv']}
In [11]: palin
Out[11]: {'Name': 'Michael Palin', 'Occupations': ['comedian', 'actor', 'writer', 'tv']}
#可以通过键来调用对应的数据In [13]: palin['Name']
Out[13]: 'Michael Palin'
#如果字典中一个键对应着多个数据项，也可以使用类似列表的记号访问。In [15]: palin['Occupations'][-1]
Out[15]: 'tv'
In [16]: palin['Occupations'][1]
Out[16]: 'actor'
In [17]: palin['Occupations'][0]
Out[17]: 'comedian'
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一、对以下数据做处理，输出保留人名和比赛数据排序后的前三项。
Sarah Sweeney,2002-6-17,2:58,2.58,2:39,2-25,2-25,2:54,2.18,2:55,2:55
第一版代码：
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#!/usr/local/python3/bin/python3def sanitize(time_string):
if '-' in time_string:
splitter='-'
elif ':' in time_string:
splitter=':'
else:
return(time_string)
(mins,secs) = time_string.split(splitter)
return(mins + '.' + secs)
def get_file_data(filename):
try:
with open(filename) as f:
data = f.readline()
return(data.strip().split(','))
except IOError as ioerr:
print('File error' + str(ioerr))
return(None)
sarah1 = get_file_data('sarah2')
#这里是将列表中前两项数据，人名和生日使用pop弹出到sarah_name,sarah_dob两个变量中。(sarah_name,sarah_dob) = sarah1.pop(0),sarah1.pop(0)
#这里要做字符串拼接，所以后面的序列处理完之后，需要使用str()转换成字符串。print(sarah_name + "'s fastest times are:" + str(sorted(set([ sanitize(i) for i in sarah1 ]))[0:3]))
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输出结果：
Sarah Sweeney's fastest times are:['2.18', '2.25', '2.39']
二、上面定义的函数不变，我们使用字典的方式来完成
第二版代码：
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#!/usr/local/python3/bin/python3def sanitize(time_string):
if '-' in time_string:
splitter='-'
elif ':' in time_string:
splitter=':'
else:
return(time_string)
(mins,secs) = time_string.split(splitter)
return(mins + '.' + secs)
def get_file_data(filename):
try:
with open(filename) as f:
data = f.readline()
return(data.strip().split(','))
except IOError as ioerr:
print('File error' + str(ioerr))
return(None)
sarah1 = get_file_data('sarah2')
#定义字典sarah_dic=dict()
#将列表中前两个数据项，弹出保存到字典对应的键上。sarah_dic['name'] = sarah1.pop(0)
sarah_dic['dob'] = sarah1.pop(0)
#姓名和日期都弹出了，sarah1里面剩下的就是时间数据了，保存在sarah_dic字典中，键为time；sarah_dic['time'] = sarah1
print(sarah_dic['name'] + "'s fastest time are: " + str(sorted(set([sanitize(i) for i in sarah1]))[0:3]))
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输出结果与上面相同
三、把字典的创建移到get_file_data() 函数中，返回一个字典而不是列表。 并且把数据切片，去重复项，排序也移到get_file_data函数中，调用函数完成4个选手的成绩输出。
第三版代码：
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#!/usr/local/python3/bin/python3def sanitize(time_string):
if '-' in time_string:
splitter='-'
elif ':' in time_string:
splitter=':'
else:
return(time_string)
(mins,secs) = time_string.split(splitter)
return(mins + '.' + secs)
def get_file_data(filename):
try:
with open(filename) as f:
data = f.readline()
templ = data.strip().split(',')
return({'name':templ.pop(0),
'dob':templ.pop(0),
'time':str(sorted(set([sanitize(i) for i in templ]))[0:3])})
except IOError as ioerr:
print('File error' + str(ioerr))
return(None)
james1 = get_file_data('james2')
julie1 = get_file_data('julie2')
mikey1 = get_file_data('mikey2')
sarah1 = get_file_data('sarah2')
print(james1['name'] + "'s fastest time are: " + james1['time'])
print(julie1['name'] + "'s fastest time are: " + julie1['time'])
print(mikey1['name'] + "'s fastest time are: " + mikey1['time'])
print(sarah1['name'] + "'s fastest time are: " + sarah1['time'])
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输出结果：
难点：
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def get_file_data(filename):
try:
with open(filename) as f:
data = f.readline()
templ = data.strip().split(',')
#可以看到这里是返回字典了，发现连字典名都没有，直接返回的是键和对应的数据。 return({'name':templ.pop(0),
'dob':templ.pop(0),
'time':str(sorted(set([sanitize(i) for i in templ]))[0:3])})
except IOError as ioerr:
print('File error' + str(ioerr))
return(None)
#由于返回过来的直接是字典数据，这里用任何的变量调函数，都会变成字典，而函数返回键值对应的数据就保存在该字典中。james1 = get_file_data('james2')
#这里就可以使用字典和键"james1['name']"来输出数据了。print(james1['name'] + "'s fastest time are: " + james1['time'])
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引入Class代替字典重构程序：
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#!/usr/local/python3/bin/python3#def sanitize(time_string):
if '-' in time_string:
splitter='-'
elif ':' in time_string:
splitter=':'
else:
return(time_string)
(mins,secs) = time_string.split(splitter)
return(mins + '.' + secs)
class Athlete():
def __init__(self,a_name,a_dob,a_times=[]):
self.name = a_name
self.dob = a_dob
self.time = a_times
def top3(self):
return(sorted(set(sanitize(i) for i in self.time))[0:3])
def get_file_data(filename):
try:
with open(filename) as f:
data = f.readline()
templ = data.strip().split(',')
#这里是直接返回类，并且把类可以被传入的参数一并返回。 return (Athlete(templ.pop(0),templ.pop(0),templ))
except IOError as ioerr:
print('File error' + str(ioerr))
return(None)
#由于函数直接返回的是类，这里用任何变量，都会成为返回类的实例化对象。 james1 = get_file_data('james2')
julie1 = get_file_data('julie2')
mikey1 = get_file_data('mikey2')
sarah1 = get_file_data('sarah2')
print(james1.name + "'s fastest time are: " + str(james1.top3()))
print(julie1.name + "'s fastest time are: " + str(julie1.top3()))
print(mikey1.name + "'s fastest time are: " + str(mikey1.top3()))
print(sarah1.name + "'s fastest time are: " + str(sarah1.top3()))
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#这里的print是在玩字符串拼接，所以str要把sarah1.top3()实例的方法输出，转换为字符串才能拼接。