Question

我的输入文件看起来像 this （infile.txt）：

a x
b y
c z

我想实现一个程序，使用户可以根据命令写入STDOUT或文件：

python mycode.py infile.txt outfile.txt

将写入文件。

用这个

python mycode.py infile.txt #2nd case

将写入STDOUT。

我坚持使用这段代码：

import sys
import csv

nof_args = len(sys.argv)
infile  = sys.argv[1]

print nof_args
outfile = ''
if nof_args == 3:
    outfile = sys.argv[2]

# for some reason infile is so large
# so we can't save it to data structure (e.g. list) for further processing
with open(infile, 'rU') as tsvfile:
    tabreader = csv.reader(tsvfile, delimiter=' ')

    with open(outfile, 'w') as file:
        for line in tabreader:
            outline = "__".join(line)
            # and more processing
            if nof_args == 3:
                file.write(outline + "\n")
            else:
                print outline
    file.close()

使用第二种情况时会产生

Traceback (most recent call last):
  File "test.py", line 18, in <module>
    with open(outfile, 'w') as file:
IOError: [Errno 2] No such file or directory: ''

实施它的更好方法是什么？

Answer 1

你可以试试这个：

import sys

if write_to_file:
    out = open(file_name, 'w')
else:
    out = sys.stdout

# or a one-liner:
# out = open(file_name, 'w') if write_to_file else sys.stdout

for stuff in data:
    out.write(stuff)

out.flush() # cannot close stdout

# Python deals with open files automatically

您也可以使用此代替out.flush()：

try:
    out.close()
except AttributeError:
    pass

这看起来有点难看，所以，flush会很好。

如何根据参数输入实现STDOUT和文件写入

1 个答案: