将相对路径解析为 Python 中的另一个相对路径

Question

I have a relative path which is relative to another relative path, and I want to join them:

rel_path1 = '../../data/a'
rel_path2 = '../../main.xml'

# pseudo function: join_rel_paths
result = join_rel_paths(rel_path1, rel_path2)

# My expectation
expected_result = '../../../main.xml'

assert result == expected_result

Is there any lib which could achieve this?

• I tried pathlib.Path : (Path(rel_path1) / Path(rel_path2)).resolve() -> it returns an absolute path with cwd
• I tried urllib.parse.urljoin : urljoin(rel_path1, rel_path2) -> main.xml not what I want

Answer 1

The expected result of your example should be ../../main.xml , ie the same as rel_path2 . The two .. in rel_path2 strip off the last two components from rel_path1 , leaving it as ../.. . Then main.xml follows. (But look further down to see how to strip off the last component of rel_path1 .)

You can achieve this by using os.path.join followed by os.path.normpath :

rel_path1 = '../../data/a'
rel_path2 = '../../main.xml'

tmp = os.path.join(rel_path1, rel_path2)
result = os.path.normpath(tmp)

This gives '../../data/a/../../main.xml' for tmp and '../../main.xml' for result .

If you want to treat the last component of rel_path1 as a file (and ignore it), you can use os.path.dirname to do so:

rel_path1b = os.path.dirname(rel_path1)

This sets rel_path1b to '../../data' , which you can then use in place of rel_path1 to obtain '../../../main.xml' .