Question

我有一个html scraper，可以从网站上获取商品和价格的标题。有一段时间我想运行这个刮刀来更新我的价格，这样做我也希望保留旧的。

我的csv第一次保存标题和价格是这样的：

Title1, price1, 'END'
Title2, price2, 'END'
Title3, price3, 'END'

我使用以下方法将新价格与旧价格进行比较：

ind = row.index('END')
lastprijs = row[ind-1]
print lastprijs
if lastprijs != prijstitel:
    row.pop(ind)
    row.append(prijstitel)
    row.append("END")

如果找到（并设置）了一个值，我用

更新csv

with open('out.csv', 'a') as out:
    tester = csv.writer(out)
    tester.writerow(row)

如果没有找到值，我用相同的行更新csv：

else: 
    with open('out.csv', 'a') as out:
        tester = csv.writer(out)
        row.append("addedddd")   #add a new line.
        tester.writerow(row)

然而，运行后我的csv的输出如下：

Item1, price1, 'END'
Item2, price2, 'END'
Item3, price3, 'END'
Item1, price1, 'END'
item1, price1, 'END'
Item2, price2, 'END'
Item3, price3, 'END'
Item1, price1, 'END'
item1, price1, 'END'
Item2, price2, 'END'
Item2, price2, 'END'
Item3, price3, 'END'
Item1, price1, 'END'

依旧...... 我该如何解决这个问题？

**完整的代码**

def updateprices(prijstitel, titelprijs):
  with open('pricewatch.csv', 'r') as csvfileadjust:
    filereader = csv.reader(csvfileadjust)
    print titelprijs
    if titelprijs == "Gembird externe Hardeschijf behuizing met USB 2.0 aansluiting":
        prijstitel = 'EDITED PRIJS!'
    for row in filereader:
        header = row
        print header
        print " ---- "
        if titelprijs in row:
            ind = row.index('END')
            lastprijs = row[ind-1]
            print lastprijs
            if lastprijs != prijstitel:
                row.pop(ind)
                row.append(prijstitel)
                row.append("END")
            with open('out.csv', 'a') as out:
                tester = csv.writer(out)
                tester.writerow(row)
        else: 
            with open('out.csv', 'a') as out:
                tester = csv.writer(out)
                row.append("addedddd")   #add a new line.
                tester.writerow(row)

Answer 1

你的问题是正确的，

这可以解决您的问题

x=0
while x < 20:  Or length of csv file.
   updateprices("10,00","TITELS", x)
   x+=1

def updateprices(prijstitel, titelprijs, var):
  with open(csvfile, 'r') as csvfileadjust:  #open the file
    filereader = csv.reader(csvfileadjust)
    row = list(islice(filereader,var+1))[-1]  #get all lines till var+1
    if titelprijs in row:  #if the title is in the row
        ind = row.index('END')  #search for END in that List
        lastprijs = row[ind-1] 
        print lastprijs
        if lastprijs != prijstitel:  #if lastprijs is not equal to prijstitel ( 9,99 != 10,00)
            row.pop(ind)  #drop the last item in list ("END")
            row.append(prijstitel)  #add the new prijstitel (10,00)
            row.append("END")  
        with open('out.csv', 'a') as out:
            tester = csv.writer(out)  
            tester.writerow(row)   #Write to csv file
    else:   #if the title is not in the row
        with open('out.csv', 'a') as out:
            tester = csv.writer(out)
            tester.writerow(row)  #write (or copy) the line

Python替换CSV文件的单元格

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