如何逐行读取2个文件并在处理后编辑每一行

Question

我有如下代码，如果file1中读取的行满足我的条件，我就要编辑/更新file1。否则，我要编辑文件2中满足另一个条件的行：

with gzip.open('/my/file1.txt.gz', 'r') as f:
    for line in csv.reader(f, delimiter="\t"):
        if (str(line[3]) == "C"):
            # edit/update the line from file 1
        else:
            with gzip.open('/my/file2.txt.gz', 'r') as f2:
                for line2 in csv.reader(f2, delimiter="\t"):
                    if line2[0] == line[0]:
                        # edit/update the line2 from file 2

有没有办法做到这一点？提前谢谢！你知道吗

Answer 1

一些问题：

• 您正在尝试更新只读文件；

• 您似乎想在读取文件时更新它。对于纯文本文件，只要替换字符串的长度与其替换的字符串的长度完全相同，就可以执行此操作。但是这是一个压缩文件-我认为你会破坏文件。

• 每次要修改第二个文件时，都要重新读取它。

如果可能的话，我建议把整部作品读入记忆，做出修改，然后全部写出来：

import csv, gzip
from collections import defaultdict

def read_gzip(fname):
    with gzip.open(fname, 'rb') as inf:
        incsv = csv.reader(inf, delimiter='\t')
        return list(incsv)

def write_gzip(fname, data):
    with gzip.open(fname, 'wb') as outf:
        outcsv = csv.writer(outf, delimiter='\t')
        outcsv.writerows(data)

def main():
    f1, f1_dirty = read_gzip('/my/file1.txt.gz'), False
    f2, f2_dirty = read_gzip('/my/file2.txt.gz'), False

    # make row index on f2
    idx = defaultdict(list)
    for row in f2:
        idx[row[0]].append(row)

    # process files
    for row in f1:
        if row[3] == 'C':
            # modify row data
            f1_dirty = True
        else:
            for other in idx[row[0]]:
                # modify other
                f2_dirty = True

    if f1_dirty: write_gzip('/my/file1.txt.gz', f1)
    if f2_dirty: write_gzip('/my/file2.txt.gz', f2)

if __name__=="__main__":
    main()

Answer 2

这一行中的一些：

keys = set()
with gzip.open('/my/file1.txt.gz', 'r') as src_file:
    for line in csv.reader(src_file, delimiter="\t"):
        if (str(line[3]) == "C"):
            # edit/update the line from file 1
        else:
            keys.add(line[0])

with gzip.open('/my/file2.txt.gz', 'r') as target_file:
    for line in csv.reader(target_file, delimiter="\t"):
        if line[0] in keys: