Python 3.4：从csv匹配并返回匹配值为

Question

问题

如何扫描阅读器csv以获取reader2 csv中的任何项目，并返回带有匹配信息的新csv。

Reader2 csv格式

66740,1800,1001463,1467373,896159

reader csv format

1001385|NORTHWEST PIPE CO|10-Q|2015-05-06|edgar/data/1001385/0001193125-15-174814.txt
1001426|PERICOM SEMICONDUCTOR CORP|10-Q|2015-05-05|edgar/data/1001426/0001145443-15-000628.txt
1001463|Acacia Diversified Holdings, Inc.|10-K|2015-05-20|edgar/data/1001463/0001185185-15-001386.txt
1001463|Acacia Diversified Holdings, Inc.|10-K|2015-05-20|edgar/data/1001463/0001185185-15-001394.txt
1001463|Acacia Diversified Holdings, Inc.|10-Q|2015-05-20|edgar/data/1001463/0001185185-15-001388.txt
1001463|Acacia Diversified Holdings, Inc.|10-Q|2015-05-20|edgar/data/1001463/0001185185-15-001390.txt
1001463|Acacia Diversified Holdings, Inc.|10-Q|2015-05-20|edgar/data/1001463/0001185185-15-001392.txt
1001463|Acacia Diversified Holdings, Inc.|10-Q|2015-05-20|edgar/data/1001463/0001185185-15-001396.txt

当前代码

with open('newCIK.csv') as reader2:
    reader2 = csv.reader(reader2)

    with open('search.file') as f_in, open('SP500_10K.csv', 'w') as f_out:
        reader = csv.reader(f_in, delimiter='|')
        writer = csv.writer(f_out, delimiter='|')

        for line in reader:
            for cik in reader2:
                if cik in line:
                    writer.writerow(line)

Answer 1

您正在尝试将文件对象视为列表，并多次循环它。如果不做额外的工作，这将无法奏效。而且，你没有遍历一行的列;您正在尝试测试整行是否在其他CSV文件行中。您需要测试每个值，然后只测试search.file CSV数据中行的最后一列。

文件对象具有文件位置;当你从文件中读取时，位置从开始到结束。一旦到达，它将不会自动再次启动。

您可以再次查找文件对象：

with open('newCIK.csv') as reader2_file:
    reader2 = csv.reader(reader2_file)

    with open('search.file') as f_in, open('SP500_10K.csv', 'w') as f_out:
        reader = csv.reader(f_in, delimiter='|')
        writer = csv.writer(f_out, delimiter='|')

        for line in reader:
            reader2_file.seek(0)  # rewind to the start
            for cik in reader2:
                if cik in line:
                    writer.writerow(line)

但是，一遍又一遍地读取文件慢。你最好在开始时将整个内容读入内存。上面没有解决另一个问题，即您正在测试newCIK.csv中的每一行而不是每一列。

将 one 行读入内存，然后循环遍历：

with open('newCIK.csv', newline='') as reader2:
    reader2 = csv.reader(reader2)
    cik_values = next(reader2)  # first row

with open('search.file', newline='') as f_in, open('SP500_10K.csv', 'w', newline='') as f_out:
    reader = csv.reader(f_in, delimiter='|')
    writer = csv.writer(f_out, delimiter='|')

    for line in reader:
        for cik in cik_values:
            if cik in line[-1]:  # test only the last column
                writer.writerow(line)

请注意，我在newline=''个调用中添加了open()个参数; csv模块需要更多地控制换行符;如果不这样做可能会导致Windows上出现问题以及处理包含换行符的值时出现问题。

演示：

>>> from io import StringIO
>>> import csv, sys
>>> newcik = '''\
... 66740,1800,1001463,1467373,896159
... '''
>>> search_file = '''\
... 1001385|NORTHWEST PIPE CO|10-Q|2015-05-06|edgar/data/1001385/0001193125-15-174814.txt
... 1001426|PERICOM SEMICONDUCTOR CORP|10-Q|2015-05-05|edgar/data/1001426/0001145443-15-000628.txt
... 1001463|Acacia Diversified Holdings, Inc.|10-K|2015-05-20|edgar/data/1001463/0001185185-15-001386.txt
... 1001463|Acacia Diversified Holdings, Inc.|10-K|2015-05-20|edgar/data/1001463/0001185185-15-001394.txt
... 1001463|Acacia Diversified Holdings, Inc.|10-Q|2015-05-20|edgar/data/1001463/0001185185-15-001388.txt
... 1001463|Acacia Diversified Holdings, Inc.|10-Q|2015-05-20|edgar/data/1001463/0001185185-15-001390.txt
... 1001463|Acacia Diversified Holdings, Inc.|10-Q|2015-05-20|edgar/data/1001463/0001185185-15-001392.txt
... 1001463|Acacia Diversified Holdings, Inc.|10-Q|2015-05-20|edgar/data/1001463/0001185185-15-001396.txt
... '''
>>> with StringIO(newcik) as reader2:
...     reader2 = csv.reader(reader2)
...     cik_values = next(reader2)  # first row
... 
>>> with StringIO(search_file) as f_in:
...     reader = csv.reader(f_in, delimiter='|')
...     writer = csv.writer(sys.stdout, delimiter='|')
...     for line in reader:
...         for cik in cik_values:
...             if cik in line[-1]:  # test only the last column
...                 writer.writerow(line)
... 
1001463|Acacia Diversified Holdings, Inc.|10-K|2015-05-20|edgar/data/1001463/0001185185-15-001386.txt
103
1001463|Acacia Diversified Holdings, Inc.|10-K|2015-05-20|edgar/data/1001463/0001185185-15-001394.txt
103
1001463|Acacia Diversified Holdings, Inc.|10-Q|2015-05-20|edgar/data/1001463/0001185185-15-001388.txt
103
1001463|Acacia Diversified Holdings, Inc.|10-Q|2015-05-20|edgar/data/1001463/0001185185-15-001390.txt
103
1001463|Acacia Diversified Holdings, Inc.|10-Q|2015-05-20|edgar/data/1001463/0001185185-15-001392.txt
103
1001463|Acacia Diversified Holdings, Inc.|10-Q|2015-05-20|edgar/data/1001463/0001185185-15-001396.txt
103

103个数字是每个writer.writerow()调用中写入的字节数，由REPL回显。