Python CSV插入最终换行符-如何避免这种情况? [英] Python CSV insert final newline - how can I avoid it?

问题描述

假设我用两行代码创建了一个csv:

Let's say I create a csv with two lines:

>>> import csv
>>> csvfile = csv.writer(open('test.csv', 'w'))
>>> csvfile.writerow(['row'])
5
>>> csvfile.writerow(['row2'])
6

阅读时，我得到最后一行:

When reading it, I get a final new line:

>>> open('test.csv').read()
'row\nrow2\n'

当然，这是可以预期的，但是在我的情况下，我不希望使用它，因为它更容易解释:进行拆分时无需检查空行.

Of course, this can be expected, but in my case I would prefer not to have it since it would be easier to interpret: No need to check for empty lines when doing a split.

>>> open('test.csv').read().split('\n')
['row', 'row2', '']

推荐答案

作为解决方法，您可以使用

As a workaround you could use a StringIO() object to write to. The output could then have rstrip() applied to it before writing to a file:

from io import StringIO        
import csv

output = StringIO(newline='')
csvfile = csv.writer(output)

csvfile.writerow(['row'])
csvfile.writerow(['row2'])        

with open('test.csv', 'w', newline='') as f_output:
    f_output.write(output.getvalue().rstrip())

这样做的好处是保留了CSV库的全部功能.不过，我建议您保留尾随换行符.

This has the benefit of preserving the full functionality of the CSV library. I would though recommend you keep the trailing newline.

对于迭代方法:

from io import StringIO        
import csv

data = [['row'], ['row2']]

with open('test.csv', 'w', newline='') as f_output:
    iter_data = iter(data)
    next_row = next(iter_data)
    csv_writer = csv.writer(f_output)

    for row in iter_data:
        csv_writer.writerow(next_row)
        next_row = row

    # Write the last row to a string to remove trailing newline
    last_row = StringIO(newline='')
    csv.writer(last_row).writerow(next_row)
    f_output.write(last_row.getvalue().rstrip())        

这一次将数据写入一行，然后使用StringIO()方法删除最后一行的换行符，然后处理最后一行.

This writes the data a row at a time and then deals with the last row using the StringIO() approach to remove the trailing newline.

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