Hands on the Python submodule os.path

Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!

Comments¶

It is suggested that you use use pathlib package instead of os.path.

import os
import inspect

abspath¶

https://docs.python.org/3/library/os.path.html#os.path.abspath

Return a normalized absolutized version of the pathname path. Notice that a path that is a symbolic link is not automatically traced to the original path. You have to use the function os.path.realpath to get the original path of a file. Notice that os.path.realpath calls os.path.abspath internally so that you do not need to call os.path.abspath by yourself when you use os.path.realpath.

os.path.abspath("path.ipynb")

'/workdir/learning/0-programming/1-python/3-file_system/os/path.ipynb'

print(inspect.getsource(os.path.abspath))

def abspath(path):
    """Return an absolute path."""
    path = os.fspath(path)
    if not isabs(path):
        if isinstance(path, bytes):
            cwd = os.getcwdb()
        else:
            cwd = os.getcwd()
        path = join(cwd, path)
    return normpath(path)

dirname¶

path.dirname(path.abspath("path.ipynb"))

'/jupyter/learning/python/file_system'

basename¶

path.basename(path.abspath("path.ipynb"))

'path.ipynb'

path.basename("path.ipynb")

'path.ipynb'

os.path.pardir¶

os.path.pardir is not a directory but instead a str object '..'.

os.path.realpath(os.path.join("/home/dclong", os.path.pardir))

'/home'

The parent directory of / is itself.

os.path.realpath(os.path.join("/", os.path.pardir))

'/'

isdir¶

path.isdir("/home/dclong")

True

isfile¶

Returns True on 1. file 2. symbolic link to file

Returns False on 1. directory 2. symbolic link to directory

import os

# /home/chud is a directory
os.path.isfile("/home/dclong")

False

import os

# test.dat is a symbolic link to test.txt
os.path.isfile("test.dat")

True

exists¶

path.exists("/home/dclong")

True

%ls

path.ipynb*

dir(path)

['__all__',
 '__builtins__',
 '__cached__',
 '__doc__',
 '__file__',
 '__loader__',
 '__name__',
 '__package__',
 '__spec__',
 '_get_sep',
 '_joinrealpath',
 '_varprog',
 '_varprogb',
 'abspath',
 'altsep',
 'basename',
 'commonpath',
 'commonprefix',
 'curdir',
 'defpath',
 'devnull',
 'dirname',
 'exists',
 'expanduser',
 'expandvars',
 'extsep',
 'genericpath',
 'getatime',
 'getctime',
 'getmtime',
 'getsize',
 'isabs',
 'isdir',
 'isfile',
 'islink',
 'ismount',
 'join',
 'lexists',
 'normcase',
 'normpath',
 'os',
 'pardir',
 'pathsep',
 'realpath',
 'relpath',
 'samefile',
 'sameopenfile',
 'samestat',
 'sep',
 'split',
 'splitdrive',
 'splitext',
 'stat',
 'supports_unicode_filenames',
 'sys']

expanduser¶

os.path.expanduser("~")

'/Users/dclong'

os.path.realpath(path)¶

os.path.realpath returns the canonical path of the specified filename, eliminating any symbolic links encountered in the path.

Notice that os.path.realpath calls os.path.abspath so that you do not have to call os.path.abspath by yourself when you call os.path.realpath.

print(inspect.getsource(os.path.realpath))

def realpath(filename):
    """Return the canonical path of the specified filename, eliminating any
symbolic links encountered in the path."""
    filename = os.fspath(filename)
    path, ok = _joinrealpath(filename[:0], filename, {})
    return abspath(path)

os.path.splitext¶

import os

os.path.splitext("abc.txt")

('abc', '.txt')

import os

os.path.splitext("ab")

('ab', '')

arr = [0, 1]

o, v = arr

0

1

arr = [[0, 1], [0, 3]]

for o, v in arr:
    print(str(o) + ": " + str(v))

0: 1
0: 3

os.path.normpath¶

Strips the trailing forward slash from a path.

import os

os.path.normpath("./")

'.'

os.path.normpath("/some/path/")

'/some/path'

os.path.normpath("/some/path")

'/some/path'

os.path.basename("/some/path")

'path'

os.path.basename("/some/path/")

''

References¶

https://docs.python.org/3/library/filesys.html

https://docs.python.org/3/library/os.path.html