python-操作csv文件

import csv
lv,er=[],[]
#读
with open('date.csv') as mycsv:
    reader=csv.DictReader(mycsv)
    for row in reader:
        print row['difftype'],row['index'],row['type'],row['updatevalue']
print '==================='
with open('date.csv') as mycsv:
    reader=[each for each in csv.DictReader(mycsv)]
    print reader
    for row in reader:
        print row['difftype'],row['index'],row['type'],row['updatevalue']
            
        lv.append(row['difftype'])
        er.append(row['updatevalue'])

print 'lv=',lv
print 'er=',er
print '|'.join(er)
er[0],er[1]='dd','cc'
print er
print '|'.join(er)

 

 date.csv文件内容：

difftype,index,type,updatevalue
SettleDateformaterr,0,str,99999000
SettleDatenull,0,str,
Amountnull,1,num,0

ActivePython 2.7.2.5 (ActiveState Software Inc.) based on
Python 2.7.11 (v2.7.11:6d1b6a68f775, Dec  5 2015, 20:32:19) [MSC v.1500 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> ================================ RESTART ================================
>>> 
SettleDateformaterr 0 str 99999000
SettleDatenull 0 str 
Amountnull 1 num 0
===================
[{'index': '0', 'type': 'str', 'difftype': 'SettleDateformaterr', 'updatevalue': '99999000'}, {'index': '0', 'type': 'str', 'difftype': 'SettleDatenull', 'updatevalue': ''}, {'index': '1', 'type': 'num', 'difftype': 'Amountnull', 'updatevalue': '0'}]
SettleDateformaterr 0 str 99999000
SettleDatenull 0 str 
Amountnull 1 num 0
lv= ['SettleDateformaterr', 'SettleDatenull', 'Amountnull']
er= ['99999000', '', '0']
99999000||0
['dd', 'cc', '0']
dd|cc|0
>>>