Why should os.path.join be used for relative paths?

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I have a project which has several directories: Projects, Settings, Resources. What is the best practice for opening files within these directories.

Right now I'm doing:

with open(f'./Projects/{project_name}/project.txt', 'r') as f:
    ...

I've seen a lot of people recommend something like this:

projects_path = os.path.abspath(os.path.dirname(__file__))
project_path = os.path.join(projects_path, f'{project_name}/project.txt')
with open(project_path, 'r') as f:
    ...

What are the benefits of using the second method over the first? What is the best practice?

Really the second snippet should be

os.path.join(projects_path, project_name, ‘projects.txt’)

What’s the benefit? Portability. Your code can more easily run on different operating systems, since windows paths are completely different from *nix paths, but this snippet will still work on both.

This depends on if you need your code to be truly cross-platform.

Also, the absolute path allows your code to work regardless of where it’s installed or where it’s running. The current working directory might not have a "Projects" folder because it’s been executed as a shell script living in some /usr/local/bin folder.

In general, hard-coding any relative paths will yield fragile code, because now you require instructions like "this needs to be installed in (specific directory)." Robust code is always better than fragile code.

Files and File Paths, Any filenames or paths that do not begin with the root folder are assumed to be under The relative paths for folders and files in the working directory C:\bacon For instance, you've already used os.path.join() to build paths in a way that will​  os.path.join(path, *paths)¶ Join one or more path components intelligently. The return value is the concatenation of path and any members of *paths with exactly one directory separator ( os.sep ) following each non-empty part except the last, meaning that the result will only end in a separator if the last part is empty.

The only reason most people would recommend this is if you are accessing a lot of files with the same root folder (i.e. projects_path) so you do not have to type it each time. The latter is the best practice.

11.1. os.path — Common pathname manipulations, Vice versa, using bytes objects cannot represent all file names on Windows (in the standard hence Windows applications should use string objects to access all files. Unlike a unix shell, Python does not do any automatic path expansions. os.path.join("c:", "foo") represents a path relative to the current directory on drive  So, we have to come up with the path for reversestring.py. We will use os.path.join to join the directory path and name of the child directory like os.path.join(<directory1>,<directory2>). Once, we have the path to StringFunctions directory we need to add it into Pythonpath using sys.path.append(). Take a look at the code

os.path.join abstracts you from the differences between operating systems.

Using os.path.* you can run your code without worrying about the OS.

How do I interact with files in Python?, Absolute file paths are notated by a leading forward slash or drive label. If you use a relative file path from the wrong directory, then the path will refer to a we can combine data and people.txt using os.path.join to generate the relative path  os.path.join(path, *paths) Join one or more path components intelligently. The return value is the concatenation of path and any members of *paths with exactly one directory separator (os.sep) following each non-empty part except the last, meaning that the result will only end in a separator if the last part is empty.

Python, in 2020 · Sorting Algorithm Visualization : Merge Sort · Python - Itertools. os.​path.relpath() method in Python is used to get a relative filepath to the given The default value of this parameter is os.curdir which is a constant string used by the operating system to refer to the current directory. if we do not specify the start. Relative paths are relative to current working directory.If you do not your want your path to be, it must be absolute. But there is an often used trick to build an absolute path from current script: use its __file__ special attribute:

Introduction to the Python Pathlib Module, The Pathlib module can deal with absolute as well as relative paths. An absolute In that case, all the subsequent uses of classes within the module should be prefixed with pathlib . For this, os.getcwd and os.path.join functions are used. Note: We can use an absolute path from any location where as if you want to use relative path we should be present in a directory where we are going to specify relative to that present working directory. Examples of relative path and absolute path for the same operation.

Introduction to Using the OS Python Package to Set Up Working , os.path.join takes as many The example below creates a relative path to the can create paths that do not exist on You can use the os  A relative path refers to a location that is relative to a current directory. Relative paths make use of two special symbols, a dot (.) and a double-dot (..), which translate into the current directory and the parent directory. Double dots are used for moving up in the hierarchy. A single dot represents the current directory itself.

Comments
  • Your first method is dependent on the runtime working directory of your python process. The absolute path of ./Projects will change if the python process is run from different locations. The second method (using __file__) is invariant to the starting location of the process
  • No there are definitely more reasons. Not having to worry about duplicate separators for example is very convenient.