How to use pathlib.Path.expanduser() and amend and use a PosixPath value?

Question

Below shows how I obtained user1's home directory, create a new sub-directory name and create a new sub-directory there via python 3.6's os module.

>>> import os.path >>> import os >>> a = os.path.expanduser('~') >>> a '/home/user1' >>> a_sub_dir = a + '/Sub_Dir_1' >>> a_sub_dir '/home/user1/Sub_Dir_1' >>> def create_sub_dir( sub_dir ): try: os.makedirs( sub_dir, mode=0o777, exist_ok=False ) except FileExistsError: print('Sub_directory already exist, no action taken.') else: print('Created sub_directory.') >>> create_sub_dir( a_sub_dir ) Created sub_directory. >>> create_sub_dir( a_sub_dir ) Sub_directory already exist, no action taken.

I would like to achieve the same as above via python 3.6's pathlib module. However, I can't seem to get it to work (see below). My questions:

How do I use Path.expanduser()?
How do I amend the info in a PosixPath(......) since it is not a string so that I can reuse it?
I would like to amend the PosixPath and use it in my make_sub_dir() function. Will it work? Presently, I explicitly defined the new sub directory that i want to create to check that my make_sub_dir() function works.

Appreciate guidance on how to use pathlib. Thanks in advance.

>>> from pathlib import Path >>> b = Path.expanduser('~') Traceback (most recent call last): File "<pyshell#87>", line 1, in <module> b = Path.expanduser('~') File "/usr/lib/python3.6/pathlib.py", line 1438, in expanduser if (not (self._drv or self._root) and AttributeError: 'str' object has no attribute '_drv' >>> b = Path.expanduser('~/') Traceback (most recent call last): File "<pyshell#88>", line 1, in <module> b = Path.expanduser('~/') File "/usr/lib/python3.6/pathlib.py", line 1438, in expanduser if (not (self._drv or self._root) and AttributeError: 'str' object has no attribute '_drv' >>> b = Path.home() >>> b PosixPath('/home/user1') >>> b_sub_dir = b + '/Sub_Dir_1' Traceback (most recent call last): File "<pyshell#91>", line 1, in <module> b_sub_dir = b + '/Sub_Dir_1' TypeError: unsupported operand type(s) for +: 'PosixPath' and 'str' >>> def make_sub_dir( sub_dir ): try: Path(sub_dir).mkdir(mode=0o777, parents=False, exist_ok=False) except FileNotFoundError: print('Parent directory do not exist, no action taken.') except FileExistsError: print('Sub_directory already exist, no action taken.') else: print('Created sub_directory.') >>> make_sub_dir( '/home/user1/Sub_Dir_1' ) Sub_directory already exist, no action taken. >>> make_sub_dir( '/home/user1/Sub_Dir_1' ) Created sub_directory. >>> make_sub_dir( '/home/user1/Sub_Dir_1' ) Sub_directory already exist, no action taken.

FYI you should not user string concatenation to join paths, not even when using os.path... you should use os.path.join. — Giacomo Alzetta
– Giacomo Alzetta, Commented Jul 29, 2019 at 7:22

ryantuck · Accepted Answer · 2021-02-10 03:55:26Z

29

pathlib's expanduser works differently than the one in os.path: it is applied to a Path object and takes no arguments. as shown in the doc you can either use:

>>> from pathlib import Path >>> p = Path('~/films/Monty Python') >>> p.expanduser() PosixPath('/home/eric/films/Monty Python')

or work with .home():

>>> form pathlib import Path >>> Path.home() PosixPath('/home/antoine')

then in order to join directories you should use / (instead of +):

b_sub_dir = b / 'Sub_Dir_1'

edited Feb 10, 2021 at 3:55

ryantuck

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answered Jul 29, 2019 at 7:19

hiro protagonist

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6 Comments

Sun Bear Over a year ago

It just dawn on me that for question 1, I should have written it as b = Path('~').expanduser().

Sun Bear Over a year ago

Earlier, I had tried p = PosixPath('~/films/Monty Python') but got a NameError. Traceback (most recent call last): File "<pyshell#120>", line 1, in <module> p = PosixPath('~/films/Monty Python') NameError: name 'PosixPath' is not defined

Sun Bear Over a year ago

import PosixPath Traceback (most recent call last): File "<pyshell#121>", line 1, in <module> import PosixPath ModuleNotFoundError: No module named 'PosixPath'

hiro protagonist Over a year ago

should be from pathlib import Path (or PosixPath if you prefer; but Path may be more portable).

Sun Bear Over a year ago

Noted that / can be used to add directory name. How do I subtract a directory name from the PosixPath?

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