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relative paths in python modules [duplicate]

This question already has answers here:
How do you properly determine the current script directory?
(16 answers)
Closed 6 months ago.
I'm building a simple helper script for work that will copy a couple of template files in our code base to the current directory. I don't, however, have the absolute path to the directory where the templates are stored. I do have a relative path from the script but when I call the script it treats that as a path relative to the current working directory. Is there a way to specify that this relative url is from the location of the script instead?

In the file that has the script, you want to do something like this:
import os
dirname = os.path.dirname(__file__)
filename = os.path.join(dirname, 'relative/path/to/file/you/want')
This will give you the absolute path to the file you're looking for. Note that if you're using setuptools, you should probably use its package resources API instead.
UPDATE: I'm responding to a comment here so I can paste a code sample. :-)
Am I correct in thinking that __file__ is not always available (e.g. when you run the file directly rather than importing it)?
I'm assuming you mean the __main__ script when you mention running the file directly. If so, that doesn't appear to be the case on my system (python 2.5.1 on OS X 10.5.7):
#foo.py
import os
print os.getcwd()
print __file__
#in the interactive interpreter
>>> import foo
/Users/jason
foo.py
#and finally, at the shell:
~ % python foo.py
/Users/jason
foo.py
However, I do know that there are some quirks with __file__ on C extensions. For example, I can do this on my Mac:
>>> import collections #note that collections is a C extension in Python 2.5
>>> collections.__file__
'/System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/lib-
dynload/collections.so'
However, this raises an exception on my Windows machine.

It's 2018 now, and Python has already evolved to the __future__ long time ago. So how about using the amazing pathlib coming with Python 3.4 to accomplish the task instead of struggling with os, os.path, glob , shutil, etc.
So we have 3 paths here (possibly duplicated):
mod_path: which is the path of the simple helper script
src_path: which contains a couple of template files waiting to be copied.
cwd: current directory, the destination of those template files.
and the problem is: we don't have the full path of src_path, only know its relative path to the mod_path.
Now let's solve this with the amazing pathlib:
# Hope you don't be imprisoned by legacy Python code :)
from pathlib import Path
# `cwd`: current directory is straightforward
cwd = Path.cwd()
# `mod_path`: According to the accepted answer and combine with future power
# if we are in the `helper_script.py`
mod_path = Path(__file__).parent
# OR if we are `import helper_script`
mod_path = Path(helper_script.__file__).parent
# `src_path`: with the future power, it's just so straightforward
relative_path_1 = 'same/parent/with/helper/script/'
relative_path_2 = '../../or/any/level/up/'
src_path_1 = (mod_path / relative_path_1).resolve()
src_path_2 = (mod_path / relative_path_2).resolve()
In the future, it's just that simple.
Moreover, we can select and check and copy/move those template files with pathlib:
if src_path != cwd:
# When we have different types of files in the `src_path`
for template_path in src_path.glob('*.ini'):
fname = template_path.name
target = cwd / fname
if not target.exists():
# This is the COPY action
with target.open(mode='wb') as fd:
fd.write(template_path.read_bytes())
# If we want MOVE action, we could use:
# template_path.replace(target)

you need os.path.realpath (sample below adds the parent directory to your path)
import sys,os
sys.path.append(os.path.realpath('..'))

As mentioned in the accepted answer
import os
dir = os.path.dirname(__file__)
filename = os.path.join(dir, '/relative/path/to/file/you/want')
I just want to add that
the latter string can't begin with the backslash , infact no string
should include a backslash
It should be something like
import os
dir = os.path.dirname(__file__)
filename = os.path.join(dir, 'relative','path','to','file','you','want')
The accepted answer can be misleading in some cases , please refer to this link for details

Consider my code:
import os
def readFile(filename):
filehandle = open(filename)
print filehandle.read()
filehandle.close()
fileDir = os.path.dirname(os.path.realpath('__file__'))
print fileDir
#For accessing the file in the same folder
filename = "same.txt"
readFile(filename)
#For accessing the file in a folder contained in the current folder
filename = os.path.join(fileDir, 'Folder1.1/same.txt')
readFile(filename)
#For accessing the file in the parent folder of the current folder
filename = os.path.join(fileDir, '../same.txt')
readFile(filename)
#For accessing the file inside a sibling folder.
filename = os.path.join(fileDir, '../Folder2/same.txt')
filename = os.path.abspath(os.path.realpath(filename))
print filename
readFile(filename)

See sys.path
As initialized upon program startup, the first item of this list, path[0], is the directory containing the script that was used to invoke the Python interpreter.
Use this path as the root folder from which you apply your relative path
>>> import sys
>>> import os.path
>>> sys.path[0]
'C:\\Python25\\Lib\\idlelib'
>>> os.path.relpath(sys.path[0], "path_to_libs") # if you have python 2.6
>>> os.path.join(sys.path[0], "path_to_libs")
'C:\\Python25\\Lib\\idlelib\\path_to_libs'

Instead of using
import os
dirname = os.path.dirname(__file__)
filename = os.path.join(dirname, 'relative/path/to/file/you/want')
as in the accepted answer, it would be more robust to use:
import inspect
import os
dirname = os.path.dirname(os.path.abspath(inspect.stack()[0][1]))
filename = os.path.join(dirname, 'relative/path/to/file/you/want')
because using __file__ will return the file from which the module was loaded, if it was loaded from a file, so if the file with the script is called from elsewhere, the directory returned will not be correct.
These answers give more detail: https://stackoverflow.com/a/31867043/5542253 and https://stackoverflow.com/a/50502/5542253

From what suggest others and from pathlib documentation, a simple (but not ideal) solution is the following (suppose the file we need to refer to is Test/data/users.csv):
# Current file location: Tests/src/long/module/subdir/some_script.py
from pathlib import Path
# back to Tests/
PROJECT_ROOT = Path(__file__).parents[4]
# then down to Test/data/users.csv
CSV_USERS_PATH = PROJECT_ROOT / 'data' / 'users.csv'
with CSV_USERS_PATH.open() as users:
print(users.read())
This works but looks a bit odd because if you move some_script.py around, the path to the root of our project may change (and we would therefore need to change the parents[4] part).
I think I found a better solution that, based on the same idea.
We will use a file paths.py to store where the root of the project is, this file will remain at the same location compared to the root directory.
Tests
├── data
│ └── users.csv
└── src
├── long
│ └── module
│ └── subdir
│ └── some_script.py
├── main.py
└── paths.py
Where paths.py's only responsability is to provide PROJECT_ROOT:
from pathlib import Path
PROJECT_ROOT = Path(__file__).parents[1]
All scripts can now use paths.PROJECT_ROOT to express absolute paths from the root of the project. For example in src/long/module/subdir/some_script.py we could have:
from paths import PROJECT_ROOT
CSV_USERS_PATH = PROJECT_ROOT / 'data' / 'users.csv'
def hello():
with CSV_USERS_PATH.open() as f:
print(f.read())
And everything goes as expected:
~/Tests/src/$ python main.py
/Users/cglacet/Tests/data/users.csv
hello, user
~/Tests/$ python src/main.py
/Users/cglacet/Tests/data/users.csv
hello, user
The main.py script simply is:
from long.module.subdir import some_script
some_script.hello()

summary of the most important commands
>>> import os
>>> os.path.join('/home/user/tmp', 'subfolder')
'/home/user/tmp/subfolder'
>>> os.path.normpath('/home/user/tmp/../test/..')
'/home/user'
>>> os.path.relpath('/home/user/tmp', '/home/user')
'tmp'
>>> os.path.isabs('/home/user/tmp')
True
>>> os.path.isabs('/tmp')
True
>>> os.path.isabs('tmp')
False
>>> os.path.isabs('./../tmp')
False
>>> os.path.realpath('/home/user/tmp/../test/..') # follows symbolic links
'/home/user'
A detailed description is found in the docs.
These are linux paths. Windows should work analogous.

Hi first of all you should understand functions os.path.abspath(path) and os.path.relpath(path)
In short os.path.abspath(path) makes a relative path to absolute path. And if the path provided is itself a absolute path then the function returns the same path.
similarly os.path.relpath(path) makes a absolute path to relative path. And if the path provided is itself a relative path then the function returns the same path.
Below example can let you understand the above concept properly:
suppose i have a file input_file_list.txt which contains list of input files to be processed by my python script.
D:\conc\input1.dic
D:\conc\input2.dic
D:\Copyioconc\input_file_list.txt
If you see above folder structure, input_file_list.txt is present in Copyofconc folder and the files to be processed by the python script are present in conc folder
But the content of the file input_file_list.txt is as shown below:
..\conc\input1.dic
..\conc\input2.dic
And my python script is present in D: drive.
And the relative path provided in the input_file_list.txt file are relative to the path of input_file_list.txt file.
So when python script shall executed the current working directory (use os.getcwd() to get the path)
As my relative path is relative to input_file_list.txt, that is "D:\Copyofconc", i have to change the current working directory to "D:\Copyofconc".
So i have to use os.chdir('D:\Copyofconc'), so the current working directory shall be "D:\Copyofconc".
Now to get the files input1.dic and input2.dic, i will read the lines "..\conc\input1.dic" then shall use the command
input1_path= os.path.abspath('..\conc\input1.dic') (to change relative path to absolute path. Here as current working directory is "D:\Copyofconc", the file ".\conc\input1.dic" shall be accessed relative to "D:\Copyofconc")
so input1_path shall be "D:\conc\input1.dic"

This code will return the absolute path to the main script.
import os
def whereAmI():
return os.path.dirname(os.path.realpath(__import__("__main__").__file__))
This will work even in a module.

An alternative which works for me:
this_dir = os.path.dirname(__file__)
filename = os.path.realpath("{0}/relative/file.path".format(this_dir))

Example
Here's an example, tested in Python '3.9.5`:
your current directory: 'c:\project1\code\'
and you want to access the following folder: 'c:\project1\dataset\train\'.
Then you can access the folder using the following address: '../dataset/train/'
References
If you want some more information about path in Python, read this:
PEP - 355
PEP - 519

What worked for me is using sys.path.insert. Then I specified the directory I needed to go. For example I just needed to go up one directory.
import sys
sys.path.insert(0, '../')

I think to work with all systems use "ntpath" instead of "os.path". Today, it works well with Windows, Linux and Mac OSX.
import ntpath
import os
dirname = ntpath.dirname(__file__)
filename = os.path.join(dirname, 'relative/path/to/file/you/want')

A simple solution would be
import os
os.chdir(os.path.dirname(__file__))

From C:\Users\xyz\myFolder to C:\Users\xyz\testdata :
import os
working_dir = os.path.abspath(os.path.dirname(os.path.dirname(__file__)))
# C:\Users\xyz\myFolder
print(working_dir)
updated_working_dir = os.path.join(os.path.realpath(working_dir + '/../'), 'testdata')
# C:\Users\xyz\testdata
print(updated_working_dir)
Output
C:\Users\xyz\myFolder
C:\Users\xyz\testdata

Here is my sumup:
First, define the tool function named relpath, which convert a relative path to current file into a relative path to cwd
import os
relpath = lambda p: os.path.normpath(os.path.join(os.path.dirname(__file__), p))
Then we use it to wrap paths which is relative to current file
path1 = relpath('../src/main.py')
And you can also call sys.path.append() to import file relative to current file position
sys.path.append(relpath('..')) # so that you can import from upper dir
The full example code : https://gist.github.com/luochen1990/9b1ffa30f5c4a721dab5991e040e3eb1

Say the current archive named "Helper" and the upper directory named "Workshop", and the template files are in \Workshop\Templates, then the relative path in Python is "..\Templates".

This a simple way to add a relative path to the system path set . For example, for frequent case when the target directory is one level above (thus, '/../') the working directory:
import os
import sys
workingDir = os.getcwd()
targetDir = os.path.join(os.path.relpath(workingDir + '/../'),'target_directory')
sys.path.insert(0,targetDir)
This solution was tested for:
Python 3.9.6 | packaged by conda-forge | (default, Jul 11 2021,
03:37:25) [MSC v.1916 64 bit (AMD64)]

I'm not sure if this applies to some of the older versions, but I believe Python 3.3 has native relative path support.
For example the following code should create a text file in the same folder as the python script:
open("text_file_name.txt", "w+t")
(note that there shouldn't be a forward or backslash at the beginning if it's a relative path)

Output zip file to a specific directory, other than the directory of the script

I am trying to zip contents of the src folder and save the zip file in the dst folder:
import shutil
src = '/home/bart/python_projects/testenv/sampler_proj/sampler/media/audio/slices/'
dst = '/home/bart/python_projects/testenv/sampler_proj/sampler/media/audio/zipped/'
shutil.make_archive('samples', 'zip', base_dir=src, root_dir=dst)
However, the samples.zip file is not being saved to the dst folder, but to the folder in which my script resides, that is /home/bart/python_projects/testenv/sampler_proj/sampler/media/audio/.
How can I fix it?
I have looked at some other SO threads and the shutil docs, but the definitions of root_dir and base_dir are quite confusing.

According to the docs:
shutil.make_archive(base_name, format[, root_dir[, base_dir[, verbose[, dry_run[, owner[, group[, logger]]]]]]])
Create an archive file (such as zip or tar) and return its name.
base_name is the name of the file to create, including the path, minus any format-specific extension. format is the archive format: one of “zip” (if the zlib module is available), “tar”, “gztar” (if the zlib module is available), “bztar” (if the bz2 module is available), or “xztar” (if the lzma module is available).
(enphasis in bold is mine).
The first argument should include the full destination path, if you do not want the file to be in your current directory.
So you are assigning a wrong directory to root_dir I guess. According to the docs, root_dir should be:
root_dir is a directory that will be the root directory of the archive; for example, we typically chdir into root_dir before creating the archive.
Try to do:
src = '/home/bart/python_projects/testenv/sampler_proj/sampler/media/audio/slices/'
dst = '/home/bart/python_projects/testenv/sampler_proj/sampler/media/audio/zipped/'
pth = os.path.join(dst, 'samples')
shutil.make_archive(pth, 'zip', root_dir=src, base_dir=src)
In most cases, root_dir and base_dir are the same directory, the one that you want to archive. It make a sense to provide both of them for more complex cases, which does not seem your case. For example, if you want to go into a directory, and then create separate archives of subdirectories through recursion.

How to set current working directory in python in a automatic way

How can I set the current path of my python file "myproject.py" to the file itself?
I do not want something like this:
path = "the path of myproject.py"
In mathematica I can set:
SetDirectory[NotebookDirectory[]]
The advantage with the code in Mathematica is that if I change the path of my Mathematica file, for example if I give it to someone else or I put it in another folder, I do not need to do anything extra. Each time Mathematica automatically set the directory to the current folder.
I want something similar to this in Python.

The right solution is not to change the current working directory, but to get the full path to the directory containing your script or module then use os.path.join to build your files path:
import os
ROOT_PATH = os.path.dirname(os.path.abspath(__file__))
# then:
myfile_path = os.path.join(ROOT_PATH, "myfile.txt")
This is safer than messing with current working directory (hint : what would happen if another module changes the current working directory after you did but before you access your files ?)

I want to set the directory in which the python file is, as working directory
There are two step:
Find out path to the python file
Set its parent directory as the working directory
The 2nd is simple:
import os
os.chdir(module_dir) # set working directory
The 1st might be complex if you want to support a general case (python file that is run as a script directly, python file that is imported in another module, python file that is symlinked, etc). Here's one possible solution:
import inspect
import os
module_path = inspect.getfile(inspect.currentframe())
module_dir = os.path.realpath(os.path.dirname(module_path))

Use the os.getcwd() function from the built in os module also there's os.getcwdu() which returns a unicode object of the current working directory
Example usage:
import os
path = os.getcwd()
print path
#C:\Users\KDawG\Desktop\Python

Creating a relative symlink in python without using os.chdir()

Say I have a path to a file:
/path/to/some/directory/file.ext
In python, I'd like to create a symlink in the same directory as the file, that
points to the file. I'd like to end up with this:
/path/to/some/directory/symlink -> file.ext
I can do this fairly easily using os.chdir() to cd into the directory and
create the symlinks. But os.chdir() is not thread safe, so I'd like to avoid
using it. Assuming that the current working directory of the process is not
the directory with the file (os.getcwd() != '/path/to/some/directory'),
what's the best way to do this?
I guess I could create a busted link in whatever directory I'm in, then
move it to the directory with the file:
import os, shutil
os.symlink('file.ext', 'symlink')
shutil.move('symlink', '/path/to/some/directory/.')
Is there a better way to do this?
Note, I don't want to end up with is this:
/path/to/some/directory/symlink -> /path/to/some/directory/file.ext

You can also use os.path.relpath() so that you can use symlinks with relative paths. Say your script is in a directory foo/ and this directory has subdirectories src/ and dst/, and you want to create relative symlinks in dst/ to point to the files in src/. To do so, you can do:
import os
from glob import glob
for src_path in glob('src/*'):
os.symlink(
os.path.relpath(
src_path,
'dst/'
),
os.path.join('dst', os.path.basename(src_path))
)
Listing the contents of dst/ then shows:
1.txt -> ../src/1.txt
2.txt -> ../src/2.txt
Relative symlinks are useful for if you want to create a tarball of the whole foo directory tree, as I don't believe tar updates symlinks to point to the relative path inside of the generated tarball.

You could just set the second argument to the destination, like:
import os
os.symlink('file.ext', '/path/to/some/directory/symlink')

python function to create a relative symlink:
def relative_symlink(src, dst):
dir = os.path.dirname(dst)
Src = os.path.relpath(src, dir)
Dst = os.path.join(dir, os.path.basename(src))
return os.symlink(Src, Dst)

Nowadays, this can be accomplished using pathlib
from pathlib import Path
target = Path('../target.txt')
my_symlink = Path('symlink.txt')
my_symlink.symlink_to(target)
where target is a relative Path or str.

Relative paths in Python [duplicate]

This question already has answers here:
How do you properly determine the current script directory?
(16 answers)
Closed 6 months ago.
I'm building a simple helper script for work that will copy a couple of template files in our code base to the current directory. I don't, however, have the absolute path to the directory where the templates are stored. I do have a relative path from the script but when I call the script it treats that as a path relative to the current working directory. Is there a way to specify that this relative url is from the location of the script instead?

In the file that has the script, you want to do something like this:
import os
dirname = os.path.dirname(__file__)
filename = os.path.join(dirname, 'relative/path/to/file/you/want')
This will give you the absolute path to the file you're looking for. Note that if you're using setuptools, you should probably use its package resources API instead.
UPDATE: I'm responding to a comment here so I can paste a code sample. :-)
Am I correct in thinking that __file__ is not always available (e.g. when you run the file directly rather than importing it)?
I'm assuming you mean the __main__ script when you mention running the file directly. If so, that doesn't appear to be the case on my system (python 2.5.1 on OS X 10.5.7):
#foo.py
import os
print os.getcwd()
print __file__
#in the interactive interpreter
>>> import foo
/Users/jason
foo.py
#and finally, at the shell:
~ % python foo.py
/Users/jason
foo.py
However, I do know that there are some quirks with __file__ on C extensions. For example, I can do this on my Mac:
>>> import collections #note that collections is a C extension in Python 2.5
>>> collections.__file__
'/System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/lib-
dynload/collections.so'
However, this raises an exception on my Windows machine.

It's 2018 now, and Python has already evolved to the __future__ long time ago. So how about using the amazing pathlib coming with Python 3.4 to accomplish the task instead of struggling with os, os.path, glob , shutil, etc.
So we have 3 paths here (possibly duplicated):
mod_path: which is the path of the simple helper script
src_path: which contains a couple of template files waiting to be copied.
cwd: current directory, the destination of those template files.
and the problem is: we don't have the full path of src_path, only know its relative path to the mod_path.
Now let's solve this with the amazing pathlib:
# Hope you don't be imprisoned by legacy Python code :)
from pathlib import Path
# `cwd`: current directory is straightforward
cwd = Path.cwd()
# `mod_path`: According to the accepted answer and combine with future power
# if we are in the `helper_script.py`
mod_path = Path(__file__).parent
# OR if we are `import helper_script`
mod_path = Path(helper_script.__file__).parent
# `src_path`: with the future power, it's just so straightforward
relative_path_1 = 'same/parent/with/helper/script/'
relative_path_2 = '../../or/any/level/up/'
src_path_1 = (mod_path / relative_path_1).resolve()
src_path_2 = (mod_path / relative_path_2).resolve()
In the future, it's just that simple.
Moreover, we can select and check and copy/move those template files with pathlib:
if src_path != cwd:
# When we have different types of files in the `src_path`
for template_path in src_path.glob('*.ini'):
fname = template_path.name
target = cwd / fname
if not target.exists():
# This is the COPY action
with target.open(mode='wb') as fd:
fd.write(template_path.read_bytes())
# If we want MOVE action, we could use:
# template_path.replace(target)

you need os.path.realpath (sample below adds the parent directory to your path)
import sys,os
sys.path.append(os.path.realpath('..'))

As mentioned in the accepted answer
import os
dir = os.path.dirname(__file__)
filename = os.path.join(dir, '/relative/path/to/file/you/want')
I just want to add that
the latter string can't begin with the backslash , infact no string
should include a backslash
It should be something like
import os
dir = os.path.dirname(__file__)
filename = os.path.join(dir, 'relative','path','to','file','you','want')
The accepted answer can be misleading in some cases , please refer to this link for details

Consider my code:
import os
def readFile(filename):
filehandle = open(filename)
print filehandle.read()
filehandle.close()
fileDir = os.path.dirname(os.path.realpath('__file__'))
print fileDir
#For accessing the file in the same folder
filename = "same.txt"
readFile(filename)
#For accessing the file in a folder contained in the current folder
filename = os.path.join(fileDir, 'Folder1.1/same.txt')
readFile(filename)
#For accessing the file in the parent folder of the current folder
filename = os.path.join(fileDir, '../same.txt')
readFile(filename)
#For accessing the file inside a sibling folder.
filename = os.path.join(fileDir, '../Folder2/same.txt')
filename = os.path.abspath(os.path.realpath(filename))
print filename
readFile(filename)

See sys.path
As initialized upon program startup, the first item of this list, path[0], is the directory containing the script that was used to invoke the Python interpreter.
Use this path as the root folder from which you apply your relative path
>>> import sys
>>> import os.path
>>> sys.path[0]
'C:\\Python25\\Lib\\idlelib'
>>> os.path.relpath(sys.path[0], "path_to_libs") # if you have python 2.6
>>> os.path.join(sys.path[0], "path_to_libs")
'C:\\Python25\\Lib\\idlelib\\path_to_libs'

Instead of using
import os
dirname = os.path.dirname(__file__)
filename = os.path.join(dirname, 'relative/path/to/file/you/want')
as in the accepted answer, it would be more robust to use:
import inspect
import os
dirname = os.path.dirname(os.path.abspath(inspect.stack()[0][1]))
filename = os.path.join(dirname, 'relative/path/to/file/you/want')
because using __file__ will return the file from which the module was loaded, if it was loaded from a file, so if the file with the script is called from elsewhere, the directory returned will not be correct.
These answers give more detail: https://stackoverflow.com/a/31867043/5542253 and https://stackoverflow.com/a/50502/5542253

From what suggest others and from pathlib documentation, a simple (but not ideal) solution is the following (suppose the file we need to refer to is Test/data/users.csv):
# Current file location: Tests/src/long/module/subdir/some_script.py
from pathlib import Path
# back to Tests/
PROJECT_ROOT = Path(__file__).parents[4]
# then down to Test/data/users.csv
CSV_USERS_PATH = PROJECT_ROOT / 'data' / 'users.csv'
with CSV_USERS_PATH.open() as users:
print(users.read())
This works but looks a bit odd because if you move some_script.py around, the path to the root of our project may change (and we would therefore need to change the parents[4] part).
I think I found a better solution that, based on the same idea.
We will use a file paths.py to store where the root of the project is, this file will remain at the same location compared to the root directory.
Tests
├── data
│ └── users.csv
└── src
├── long
│ └── module
│ └── subdir
│ └── some_script.py
├── main.py
└── paths.py
Where paths.py's only responsability is to provide PROJECT_ROOT:
from pathlib import Path
PROJECT_ROOT = Path(__file__).parents[1]
All scripts can now use paths.PROJECT_ROOT to express absolute paths from the root of the project. For example in src/long/module/subdir/some_script.py we could have:
from paths import PROJECT_ROOT
CSV_USERS_PATH = PROJECT_ROOT / 'data' / 'users.csv'
def hello():
with CSV_USERS_PATH.open() as f:
print(f.read())
And everything goes as expected:
~/Tests/src/$ python main.py
/Users/cglacet/Tests/data/users.csv
hello, user
~/Tests/$ python src/main.py
/Users/cglacet/Tests/data/users.csv
hello, user
The main.py script simply is:
from long.module.subdir import some_script
some_script.hello()

summary of the most important commands
>>> import os
>>> os.path.join('/home/user/tmp', 'subfolder')
'/home/user/tmp/subfolder'
>>> os.path.normpath('/home/user/tmp/../test/..')
'/home/user'
>>> os.path.relpath('/home/user/tmp', '/home/user')
'tmp'
>>> os.path.isabs('/home/user/tmp')
True
>>> os.path.isabs('/tmp')
True
>>> os.path.isabs('tmp')
False
>>> os.path.isabs('./../tmp')
False
>>> os.path.realpath('/home/user/tmp/../test/..') # follows symbolic links
'/home/user'
A detailed description is found in the docs.
These are linux paths. Windows should work analogous.

Hi first of all you should understand functions os.path.abspath(path) and os.path.relpath(path)
In short os.path.abspath(path) makes a relative path to absolute path. And if the path provided is itself a absolute path then the function returns the same path.
similarly os.path.relpath(path) makes a absolute path to relative path. And if the path provided is itself a relative path then the function returns the same path.
Below example can let you understand the above concept properly:
suppose i have a file input_file_list.txt which contains list of input files to be processed by my python script.
D:\conc\input1.dic
D:\conc\input2.dic
D:\Copyioconc\input_file_list.txt
If you see above folder structure, input_file_list.txt is present in Copyofconc folder and the files to be processed by the python script are present in conc folder
But the content of the file input_file_list.txt is as shown below:
..\conc\input1.dic
..\conc\input2.dic
And my python script is present in D: drive.
And the relative path provided in the input_file_list.txt file are relative to the path of input_file_list.txt file.
So when python script shall executed the current working directory (use os.getcwd() to get the path)
As my relative path is relative to input_file_list.txt, that is "D:\Copyofconc", i have to change the current working directory to "D:\Copyofconc".
So i have to use os.chdir('D:\Copyofconc'), so the current working directory shall be "D:\Copyofconc".
Now to get the files input1.dic and input2.dic, i will read the lines "..\conc\input1.dic" then shall use the command
input1_path= os.path.abspath('..\conc\input1.dic') (to change relative path to absolute path. Here as current working directory is "D:\Copyofconc", the file ".\conc\input1.dic" shall be accessed relative to "D:\Copyofconc")
so input1_path shall be "D:\conc\input1.dic"

This code will return the absolute path to the main script.
import os
def whereAmI():
return os.path.dirname(os.path.realpath(__import__("__main__").__file__))
This will work even in a module.

An alternative which works for me:
this_dir = os.path.dirname(__file__)
filename = os.path.realpath("{0}/relative/file.path".format(this_dir))

Example
Here's an example, tested in Python '3.9.5`:
your current directory: 'c:\project1\code\'
and you want to access the following folder: 'c:\project1\dataset\train\'.
Then you can access the folder using the following address: '../dataset/train/'
References
If you want some more information about path in Python, read this:
PEP - 355
PEP - 519

What worked for me is using sys.path.insert. Then I specified the directory I needed to go. For example I just needed to go up one directory.
import sys
sys.path.insert(0, '../')

I think to work with all systems use "ntpath" instead of "os.path". Today, it works well with Windows, Linux and Mac OSX.
import ntpath
import os
dirname = ntpath.dirname(__file__)
filename = os.path.join(dirname, 'relative/path/to/file/you/want')

A simple solution would be
import os
os.chdir(os.path.dirname(__file__))

From C:\Users\xyz\myFolder to C:\Users\xyz\testdata :
import os
working_dir = os.path.abspath(os.path.dirname(os.path.dirname(__file__)))
# C:\Users\xyz\myFolder
print(working_dir)
updated_working_dir = os.path.join(os.path.realpath(working_dir + '/../'), 'testdata')
# C:\Users\xyz\testdata
print(updated_working_dir)
Output
C:\Users\xyz\myFolder
C:\Users\xyz\testdata

Here is my sumup:
First, define the tool function named relpath, which convert a relative path to current file into a relative path to cwd
import os
relpath = lambda p: os.path.normpath(os.path.join(os.path.dirname(__file__), p))
Then we use it to wrap paths which is relative to current file
path1 = relpath('../src/main.py')
And you can also call sys.path.append() to import file relative to current file position
sys.path.append(relpath('..')) # so that you can import from upper dir
The full example code : https://gist.github.com/luochen1990/9b1ffa30f5c4a721dab5991e040e3eb1

Say the current archive named "Helper" and the upper directory named "Workshop", and the template files are in \Workshop\Templates, then the relative path in Python is "..\Templates".

This a simple way to add a relative path to the system path set . For example, for frequent case when the target directory is one level above (thus, '/../') the working directory:
import os
import sys
workingDir = os.getcwd()
targetDir = os.path.join(os.path.relpath(workingDir + '/../'),'target_directory')
sys.path.insert(0,targetDir)
This solution was tested for:
Python 3.9.6 | packaged by conda-forge | (default, Jul 11 2021,
03:37:25) [MSC v.1916 64 bit (AMD64)]

I'm not sure if this applies to some of the older versions, but I believe Python 3.3 has native relative path support.
For example the following code should create a text file in the same folder as the python script:
open("text_file_name.txt", "w+t")
(note that there shouldn't be a forward or backslash at the beginning if it's a relative path)