python - 使用 python 根据公共(public)字段合并 2 个 csv 文件

Question

我从 2 个 mysql 表生成了 2 个 csv 文件。 现在我想将这两个文件合并在一起。

我为第一个 csv 手动添加了此 header :

ID,name,sector,sub_sector

这是第二个 csv header :

ID,url

我的目标是拥有 1 个文件:

ID,name,sector,sub_sector,url

注意:第一个文件中的所有记录与第二个文件中的记录并不匹配。

这是我正在使用的代码片段:

#!/usr/bin/env python
import glob, csv
if __name__ == '__main__':

    infiles = glob.glob('./*.csv')
    out = 'temp.csv'
    data = {}
    fields = []

    for fname in infiles:
        df = open(fname, 'rb')
        reader = csv.DictReader(df)
        for line in reader:
            # assuming the field is called ID
            if line['ID'] not in data:
                data[line['ID']] = line
            else:
                for k,v in line.iteritems():
                    if k not in data[line['ID']]:
                        data[line['ID']][k] = v
            for k in line.iterkeys():
                if k not in fields:
                    fields.append(k)
        del reader
        df.close()

    writer = csv.DictWriter(open(out, "wb"), fields, extrasaction='ignore', dialect='excel')
    # write the header at the top of the file
    writer.writeheader()
    writer.writerows(data)
    del writer

取自另一个软线程。 这是我收到的错误:

  File "db_work.py", line 30, in <module>
    writer.writerows(data)
  File "/usr/lib/python2.7/csv.py", line 153, in writerows
    rows.append(self._dict_to_list(rowdict))
  File "/usr/lib/python2.7/csv.py", line 144, in _dict_to_list
    ", ".join(wrong_fields))
ValueError: dict contains fields not in fieldnames: 4, 4, 4, 6
~/Development/python/DB$ python db_work.py
Traceback (most recent call last):
  File "db_work.py", line 30, in <module>
    writer.writerows(data)
  File "/usr/lib/python2.7/csv.py", line 153, in writerows
    rows.append(self._dict_to_list(rowdict))
  File "/usr/lib/python2.7/csv.py", line 145, in _dict_to_list
    return [rowdict.get(key, self.restval) for key in self.fieldnames]
AttributeError: 'str' object has no attribute 'get'

有什么想法可以解决这个问题吗？

Answer 1

.writerows()需要一个列表，但您传递的是 dict反而。我想你想写 data 的值仅:

writer = csv.DictWriter(open(out, "wb"), fields, dialect='excel')
# write the header at the top of the file
writer.writeheader()
writer.writerows(data.values())

就我个人而言，我会仅使用 id, url 来读取该文件。行，将它们添加到字典中，然后读取另一个文件并通过添加相应的 url 一次写入每一行条目。

import csv

with open('urls.csv', 'rb') as urls:
    reader = csv.reader(urls)
    reader.next()  # skip the header, won't need that here
    urls = {id: url for id, url in reader}

with open('other.csv', 'rb') as other:
    with open(out, 'wb') as output:
        reader = csv.reader(other)
        writer = csv.writer(output)
        writer.writerow(reader.next() + ['url'])  # read old header, add urls and write out
        for row in reader:
            # write out original row plus url if we can find one
            writer.writerow(row + [urls.get(row[0], '')])