在python中比较然后将行附加到csv文件

Question

我正在尝试比较 result.csv 和* street_segments.csv *中的两列，然后如果它们是* street_segments.csv *到 results.csv <的相同追加列/ em>的

import csv
count=0
count1=0
count2=0
first = file('result.csv', 'rU')
reader = csv.reader(first)

second=file('street_segments.csv', 'rU')
reader1= csv.reader(second)
for row1 in reader1:
        count +=1
        print count
        for row in reader:
            count1 += 1
            print count1
            if row[3]==row1[1]:
                row.append(row1[2])
                row.append(row1[3])
                row.append(row1[4])
                count2 += 1
                print count2

我遇到的问题是我得到的是：

1 (from count)
1 (from count1)
2 (from count1)
3(from count1)
...
200,000(from count1)
2(from count)
3(from count)
...
90000(from count)

使用嵌套的for循环，我不应该得到：

1 (from count)
1 (from count1)
2(from count1)
...
90000(from count1)
2 (from count)
1 (from count1)
2(from count1)
...
90000(from count1)
3 (from count)
1(from count1)
2(from count1)
...
90000(from count1)

你们能让我知道我做错了什么，或者是否有更好的方法解决这个问题。

所以我的results.csv文件有一行像：

-73.88637197,   40.85400596,    5327502,    P-089988,   1015684.082,    250435.3,   NO PARKING (SANITATION BROOM SYMBOL) 8:30-10AM TUES & FRI <----->

我的street_segments.csv有一行：

B,  P-004958,   RANDALL AVENUE, FAILE STREET,   COSTER STREET,  N

所以我要做的是，如果results.csv的第四列和street_segments.csv的第二列是相同的。我想将street_segments.csv的第3,4,5列添加到results.csv行的末尾。

Answer 1

您的问题是文件迭代器不会自动＆＃34;倒带＆＃34;。也就是说，当您点击外部for循环的第二次迭代时，永远不会输入内部for，因为reader（来自first）的文件指针位于文件的结尾。要解决这个问题，您需要添加first.seek(0)命令以返回文件的开头（在内循环之前）。

import csv
count=0
count1=0
count2=0
first = file('result.csv', 'rU')
reader = csv.reader(first)

second=file('street_segments.csv', 'rU')
reader1= csv.reader(second)
for row1 in reader1:
        count +=1
        print count
        # Rewind to the start of the file in preparation for the next loop
        first.seek(0)
        for row in reader:
            count1 += 1
            print count1
            if row[3]==row1[1]:
                row.append(row1[2])
                row.append(row1[3])
                row.append(row1[4])
                count2 += 1
                print count2