Question

如果一行包含来自mobilesitemap-browse.csv的字符串，我试图在相邻列的sitemap_bp.csv中追加一行。我无法遍历mobilesitemap-browse.csv中的行，它会卡在第一行。我该如何解决这个问题？

import csv

with open('sitemap_bp.csv','r') as csvinput:
    with open('mobilesitemap-browse.csv','r') as csvinput2:
        with open('output.csv', 'w') as csvoutput:
            writer = csv.writer(csvoutput, lineterminator='\n')
            sitemap = csv.reader(csvinput)
            mobilesitemap = csv.reader(csvinput2)

            all = []
            row = next(sitemap)
            row.append('mobile')
            all.append(row)

            for mobilerow in mobilesitemap:
                for row in sitemap:
                    #print row[0]
                    if mobilerow[1] in row[0]:
                        #print row, mobilerow[1]
                        all.append((row[0], mobilerow[1]))
                    else:
                        all.append(row)

            writer.writerows(all)

Answer 1

我个人首先从sitemap_bp.csv解析数据，然后使用该字典填充新文件。

import re

with open('sitemap_bp.csv','r') as csvinput, \
        open('mobilesitemap-browse.csv','r') as csvinput2, \
        open('output.csv', 'w') as csvoutput:
    writer = csv.writer(csvoutput, lineterminator='\n')
    sitemap = csvinput # no reason to pipe this through csv.reader
    mobilesitemap = csv.reader(csvinput2)

    item_number = re.compile(r"\d{5}_\d{7}_{7}")

    item_number_mapping = {item_number.search(line).group(): line.strip()
                           for line in sitemap if item_number.search(line)}
    # makes a dictionary {item_number: full_url, ...} for each item in sitemap
    # alternate to the above, consider:
    # # item_number_mapping = {}
    # # for line in sitemap:
    # #     line = line.strip()
    # #     match = item_number.search(line)
    # #     if match:
    # #         item_number_mapping[match.group()] = match.string

    all = [row + [item_number_mapping[row[1]] for row in mobilesitemap]

    writer.writerows(all)

我的猜测是，在第一次通过外部for循环之后，它会再次尝试迭代sitemap，但由于文件已经用完，所以无法再次。最小的变化是：

        for mobilerow in mobilesitemap:
            csvinput.seek(0) # seek to the start of the file object
            next(sitemap) # skip the header row
            for row in sitemap:
                #print row[0]
                if mobilerow[1] in row[0]:
                    #print row, mobilerow[1]
                    all.append((row[0], mobilerow[1]))
                else:
                    all.append(row)

但是，不这样做的显而易见的原因是它在sitemap_bp.csv中每行迭代一次mobilesitemap-browse.csv文件，而不是像我的代码一样。

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如果您需要在sitemap_bp.csv中获取与mobilesitemap-browse.csv不符的网址列表，则可能会为所有项目set提供最佳服务你看到它们，然后使用set操作来获取看不见的项目。这需要一点点修补，但是......

# instead of all = [row + [item number ...

seen = set()
all = []

for row in mobilesitemap:
    item_no = row[1]
    if item_no in item_number_mapping:
        all.append(row + [item_number_mapping[item_no]])
        seen.add(item_no)
# after this for loop, `all` is identical to the list comp version
unmatched_items = [item_number_mapping[item_num] for item_num in
                   set(item_number_mapping.keys()) - seen]

如果行包含字符串追加行，则为CSV

1 个答案:

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