layout: post title: "Python寻找环境保护署通车里程数" date: 2013-01-17 09:35 comments: true
这个程序是寻找美国环境保护署网站公布的美国各种车辆的通车历程数据。
具体的形式如下：
CLASS MFR CAR LINE DISPLACEMENT NUMB CYL TRANS DRIVE SYS INDEX NUMB CITY MPG (GUIDE) HWY MPG (GUIDE) COMB MPG (GUIDE) UNRND CITY (EPA) UNRND HWY (EPA) UNRND COMP (EPA) FUEL TYPE GUZLR TURBO SPCHGR AVG 2D PASS VOL AVG 2D LUGG VOL AVG 4D PAS VOL AVG 4D LUGG VOL AVG HB PAS VOL AVG HB LUGG VOL ANL FL CST ENG BLK TXT TRANS DESC TXT VLVS PER CYL CLS REL DT 5C CODE
TWO SEATERS ASTON MARTIN V8 VANTAGE 4.3 8 Auto(S6) R 12 13 20 15 16.1945 27.4018 19.8474 P G 3002 4MODE 4 1 6-Aug-07 DERIVED
TWO SEATERS ASTON MARTIN V8 VANTAGE 4.3 8 Manual(M6) R 11 12 19 15 15.2 25.7 18.6241 P G 3002 4 1 6-Aug-07 DERIVED
TWO SEATERS AUDI R8 4.2 8 Auto(S6) 4 19 13 19 15 16.1944 26.2 19.555 P G 3002 3MODE CLKUP 4 1 17-Aug-07 DERIVED
这里我们需要的是从零开始的第九列元素和第一列以及第二列元素。
<!--more-->现在我们使用具体的程序去计算。这里是一步步搭建整个程序网络的。
epaFile=open("epaData.csv","rU")
for line in epaFile:
if 'FERRARI' in line:
print line[:75]
#we find out the number of the car of running the miles
#we use split(',') to separate the csv value
def creatMileageList(epaFile):
mileageList=[]
for line in epaFile:
lineList=line.split(',')
mileageList.append(lineList[9])
return mileageList
epaFile=open("epaData.csv","rU")
mileageList=creatMileageList(epaFile)
print mileageList
# we further transfer the character into integer
# also ignore the class value of the first line with continue function
#continue can move into the next line without add it into the List
#when we get that done we can use max and min function to get the extreme value
def creatMileageList(epaFile):
mileageList=[]
for line in epaFile:
if line[0:5] == "CLASS":
continue
lineList=line.split(',')
temp=int(lineList[9])
mileageList.append(temp)
return mileageList
epaFile=open("epaData.csv","rU")
mileageList=creatMileageList(epaFile)
maxMileage=max(mileageList)
minMileage=min(mileageList)
print "The Max and Min in the List is:",maxMileage,minMileage
# in this case we want to also find the car trafe of the max and min Mileage
# to avoid the other visit of all the value
# we append two value together to get another list of truple
def creatMileageList(epaFile):
mileageList=[]
for line in epaFile:
if line[0:5] == "CLASS" or "VAN" in line or "PICKUP" in line:
continue
lineList=line.split(',')
temp=int(lineList[9])
carTruple=(temp,lineList[1],lineList[2])
mileageList.append(carTruple)
return mileageList
epaFile=open("epaData.csv","rU")
mileageList=creatMileageList(epaFile)
maxMileage=max(mileageList)
minMileage=min(mileageList)
print "The Max and Min in the List is:",maxMileage,minMileage
之所以会有这一步的原因在于Python默认返回的是所有最小最大值中的第一个。
所以我们构建一个列表，再次遍历列表找到相应的元素后添加。
同时对于元组构成的列表，为了美观，我们同样使用遍历的方法打印出列表中的，每一个元素。
#in this programe we want to find all the case that has the max or min value in the carMileageList
# this is because the min/max function in Python only return back the
# first found case in the list that has the same value
def creatMileageList(epaFile):
mileageList=[]
for line in epaFile:
if line[0:5] == "CLASS" or "VAN" in line or "PICKUP" in line:
continue
lineList=line.split(',')
temp=int(lineList[9])
carTuple=(temp,lineList[1],lineList[2])
mileageList.append(carTuple)
return mileageList
def FindMaxMinMileage(mileageList,maxMileage,minMileage):
maxMileageList=[]
minMileageList=[]
for carTuple in mileageList:
if carTuple[0]==maxMileage:
maxMileageList.append(carTuple)
if carTuple[0]==minMileage:
minMileageList.append(carTuple)
return maxMileageList,minMileageList
epaFile=open("epaData.csv","rU")
mileageList=creatMileageList(epaFile)
maxMileage=max(mileageList)[0]
minMileage=min(mileageList)[0]
print "The Max and Min in the List is:",maxMileage,minMileage
maxMileageList,minMileageList=FindMaxMinMileage(mileageList,maxMileage,minMileage)
#Note the print of Tuple must use visit style to get
#You can get nothing with only the print function
print "Maximum Mileage Cars:"
for carTuple in maxMileageList:
print " " ,carTuple[1],carTuple[2]
print "Minimum Mileage Cars:"
for carTuple in minMileageList:
print " ",carTuple[1],carTuple[2]