python – 删除巨大的csv中已知的确切行

import os
with open('tmp.csv','w') as tmp:

    with open('file.csv','r') as infile:
        for linenumber,line in enumerate(infile):
            if linenumber != 10234:
                tmp.write(line)

# copy back to original file. You can skip this if you don't
# mind (or prefer) having both files lying around           
with open('tmp.csv','r') as tmp:
    with open('file.csv','w') as out:
        for line in tmp:
            out.write(line)

os.remove('tmp.csv') # remove the temporary file

这会复制数据,如果磁盘空间有问题,这可能不是最佳数据.如果不首先将整个文件加载到RAM中,则写入将更复杂

关键是python自然支持处理files as iterables.这意味着它可以被懒惰地评估,你永远不需要一次把整个东西保存在内存中

我喜欢这个解决方案,如果您的主要关注点不是原始速度,因为您可以用任何条件测试替换行亚麻布！= VALUE,例如,过滤掉包含特定日期的行

test = lambda line : 'NOVEMBER' in line
with open('tmp.csv','w') as tmp:
    ...
    if test(line):
    ...

In-place read-writes和memory mapped file objects(可能相当快)将需要更多的簿记