干净的方式来获得Path对象的"真正"词干？

Question

预期的投入和产出:

a                 -> a
a.txt             -> a
archive.tar.gz    -> archive
directory/file    -> file
d.x.y.z/f.a.b.c   -> f
logs/date.log.txt -> date # Mine!

这是我对我感到肮脏的实现:

>>> from pathlib import Path
>>> example_path = Path("August 08 2015, 01'37'30.log.txt")
>>> example_path.stem
"August 08 2015, 01'37'30.log"
>>> example_path.suffixes
['.log', '.txt']
>>> suffixes_length = sum(map(len, example_path.suffixes))
>>> true_stem = example_path.name[:-suffixes_length]
>>> true_stem
"August 08 2015, 01'37'30"

因为它在Path没有后缀的情况下中断:

>>> ns_path = Path("no_suffix")
>>> sl = sum(map(len, ns_path.suffixes))
>>> ns_path.name[:-sl]
''

所以我需要先检查Path后缀是否有后缀:

>>> def get_true_stem(path: Path):
...     if path.suffix:
...         sl = sum(map(len, path.suffixes))
...         return path.name[:-sl]
...     else:
...         return path.stem
...
>>>
>>> get_true_stem(example_path)
"August 08, 2015, 01'37'30"
>>> get_true_stem(ns_path)
"no_suffix"

这是我目前的用例:

>>> file_date = datetime.strptime(true_stem, "%B %d %Y, %H'%M'%S")
>>> file_date
datetime.datetime(2015, 8, 8, 1, 37, 30)
>>> new_dest = format(file_date, "%Y-%m-%dT%H:%M:%S%z") + ".log" # ISO-8601
>>> shutil.move(str(example_path), new_dest)

谢谢.

Answer 1

你可以.split这样:

>>> Path('logs/date.log.txt').stem.split('.')[0]
'date'

os.path 同样有效:

>>> os.path.basename('logs/date.log.txt').split('.')[0]
'date'

它通过了所有测试:

In [11]: all(Path(k).stem.split('.')[0] == v for k, v in {
   ....:     'a': 'a',
   ....:     'a.txt': 'a',
   ....:     'archive.tar.gz': 'archive',
   ....:     'directory/file': 'file',
   ....:     'd.x.y.z/f.a.b.c': 'f',
   ....:     'logs/date.log.txt': 'date'
   ....: }.items())
Out[11]: True

Answer 2

为什么不递归呢？

from pathlib import Path

def true_stem(path):
   stem = Path(path).stem
   return stem if stem == path else true_stem(stem)

assert(true_stem('d.x.y.z/f.a.b.c') == 'f')

Answer 3

这是给定问题的另一种可能的解决方案：

from pathlib import Path

if __name__ == '__main__':
    dataset = [
        ('a', 'a'),
        ('a.txt', 'a'),
        ('archive.tar.gz', 'archive'),
        ('directory/file', 'file'),
        ('d.x.y.z/f.a.b.c', 'f'),
        ('logs/date.log.txt', 'date'),
    ]
    for path, stem in dataset:
        path = Path(path)
        assert path.name.replace("".join(path.suffixes), "") == stem

Answer 4

一个 while 循环方法怎么样，你继续使用.stem直到路径没有后缀剩余，例如 -

from pathlib import Path
example_path = Path("August 08 2015, 01'37'30.log.txt")
example_path_stem = example_path.stem
while example_path.suffixes:
    example_path_stem = example_path.stem
    example_path = Path(example_path_stem)

请注意，while 循环在example_path.suffixes返回空列表时退出循环（因为空列表在布尔上下文中为 False）。

示例/演示 -

>>> from pathlib import Path
>>> example_path = Path("August 08 2015, 01'37'30.log.txt")
>>> example_path_stem = example_path.stem
>>> while example_path.suffixes:
...     example_path_stem = example_path.stem
...     example_path = Path(example_path_stem)
...
>>> example_path_stem
"August 08 2015, 01'37'30"

对于您的第二个输入 - no_suffix-

>>> example_path = Path("no_suffix")
>>> example_path_stem = example_path.stem
>>> while example_path.suffixes:
...     example_path_stem = example_path.stem
...     example_path = Path(example_path_stem)
...
>>> example_path_stem
'no_suffix'