os.path.join – Joining Paths in Python

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Python os.path.join() Method Example

The OS module in Python implements some valuable functions on pathnames. The os.path sub-module is always suitable for the operating system.

What is a file path in Python?

The file path consists of a sequence of file and folder names. This sequence of names walks you to a specific place on your computer’s operating system (OS).

path = "/Users/krunal/Desktop/code/"

The above path takes us to the code folder or directory.

To get the path dynamically without hardcoding, use the os.path.join() method. The idea of os.path.join() is to make your program cross-platform. Let’s see this method in detail.

What is os.path.join?

The os.path.join is a built-in Python function that joins one or more path components. The os.path.join() function concatenates several path components with precisely one directory separator (‘/’) following each non-empty part minus the last path component. If the last path segment to be joined is empty, then a directory separator (‘/’) is placed at the end.

How to Use os.path.join?

To use the os.path.join() method in Python, import the os.path sub-module, and use that sub-module’s join() method.

Syntax

os.path.join(path, *paths)

Parameters

path: A path-like object representing a file system path.

*path: A path-like object representing a file system path. It represents the path components to be joined.

Return Value

The os.path.join() method returns a string that represents the concatenated path components.

Why os.path.join() function is important?

The os.path.join() method is important because it helps us create valid paths on any operating system. If you’ve worked with file systems in Python, you must have used the os.path sub-module.

How to join paths in Python?

To join the path in Python, use the os.path.join() function. The os.path.join() method is frequently used with os methods like os.walk() to create a final path for a file or folder. The os.path.join() inserts any required forward slashes into the file pathname.

Write the following code that demonstrates the path.join() method.

import os

path = "/Users/krunal/Desktop/code/"

print(os.path.join(path, "pyt", "database", "app.py"))

Output

/Users/krunal/Desktop/code/pyt/database/app.py

As you can see from the output that the os.path.join() function combines path names into one complete path. That means you can join multiple path segments into one instead of manually hard-coding every pathname.

To get a current working directory in Python, use the following file pathname.

import os

cwd = os.getcwd()

print(cwd)

Output

/Users/krunal/Desktop/code/pyt/database

The os.path.expanduser() method will expand the pathname that uses ~ to represent the current user’s home directory.

This works on any platform where users have a home directory, including Linux, MacOS, and Windows. The returned path does not have a trailing slash but the os.path.join() method doesn’t care.

Let’s not use the hardcoded path; let’s use the Python functions to print the complete path up to the desired filename.

import os

cwd = os.getcwd()

app = os.path.join(cwd, "app.py")

print(app)

Output

/Users/krunal/Desktop/code/pyt/database/app.py

The cwd variable saves the file path for the database folder relative to our current working directory, and then we join it with the app.py filename.

How to join two paths in Python?

To join two paths in Python, use the os.path.join() method. The os.path.join() function concatenates two path components with a directory separator (‘/’).

The os.path.join() function intelligently joins two path components. If any component is an absolute path, all previous components are hurled away and joining continues from the absolute path component.

os.path.join: os is not defined

Python “NameError: name ‘os’ is not defined” occurs when we use the os module without importing it into our program. To solve the ‘os not defined error in Python’, import the os module before using it.

os.path.join not working

The os.path.join function won’t work if a component is an absolute path because all previous components are thrown away and joining continues from the absolute path component.

The path strings shouldn’t start with a slash. If they start with a slash, they are believed to be an “absolute path”, and everything before them is dumped. Therefore, doo does not use forward slashes at the beginning of path components except when referring to the root directory.

os.path.join(base_dir ‘templates’)

If you are working with Django, in your settings.py file, the terminal shows the following error.

File “/home/pipo/Desktop/mysite/mysite/settings.py”, line 116, in <module> [os.path.join(BASE_DIR, ‘templates’)]

NameError: name ‘os’ is not defined

To solve NameError: name ‘os’ is not defined in Django, add the import os line at the beginning of the settings.py file.

What is os.path.abspath(os.path.join(os.path.dirname(__file__), os.path.pardir))

The os.path.abspath(os.path.join(os.path.dirname(__file__), os.path.pardir)) is a clever function or approach to refer to paths regardless of the script location. There arethree3 methods andtwo2 constants present:

  1. os.path.abspath: The abspath() function returns the absolute path of a path.
  2. os.path.join: The join() function joins the path strings.
  3. os.path.dirname: The dirname() function returns the directory of a file
  4. __file__ : The __file__ constant refers to the script’s file name
  5. os.pardir: The pardir returns the representation of a parent directory in the OS.

Conclusion

The os.path.join() method merges components in a pathname to create a full pathname. It automatically adds forward slashes (“/”) into the pathname when needed.

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