Python – Relative Paths Using “path.relpath”

In my previous tutorial related to Relative Paths in Python, I explained how to exploit some of the path methods to retrieve the relative path? In this tutorial, I will explain how to use the “path.relpath” with a very interesting example. So let’s begin…

Here’s my folder structure

C:
|----SampleDir
|    |----Dir A
|         |----Sub Dir A
|              |----Source A
|                   |----RelativePathSample.py
|
|----SampleDir
|    |----Dir B
|         |----Sub Dir B
|              |----Target B
|                   |----TargetModule.py

So here’s the problem I want to solve

“RelativePathSample.py needs to import a class called someClass from TargetModule.py”

Here’s what we know

• The folder structure (a developer should know this before coding though!)
• Path of TargetModule.py
• Name of the class to be imported ie someClass

Now, let’s try to solve the problem.

To solve this problem I am going to use path.relpath (read the official documentation here. In nutshell this method accepts two arguments

1. path of the file of which we want to find the relative path
2. starting directory (This is optional. By default method uses the directory of the current file i.e. os.curdir )

If I want to access a class someClass in the TargetModule.py first we will need to add the directory of the TargetModule.py into Pythonpath.

Don’t laugh!! I know the directory path of the TargetModule.py It’s just that we all are learning to use path.relpath that’s why I am not directly using what I know!

Let’s continue…

Take a look at following code

targetFile = "C:/SampleDir/Dir B/Sub Dir B/Target B/TargetModule.py"
reldirFilePath = os.path.relpath(targetFile) # Relative file path wrt current directory
    reldirPath = os.path.dirname(reldirFilePath) # Directory of relative file path
sys.path.insert(0, reldirPath)

I think it is self-explanatory. I have a given path the targetFile and I want to add the relative path for this file into Pythonpath. Hence I used os.path.relpath which gave the target file path wrt current directory. Now I used os.path.dirname to get the directory path of the file. Then I used sys.path.insert to add this directory into the Pythonpath.

Now here’s my complete code

The someClass which I want to use in my example module.

TargetModule.py

# TargetModule.py
class someClass(object):
    
    someProperty = 0

    def __init__(self,*args):
        self.someProperty = args[0]

    def outputProperty(self):
        print(self.someProperty)

RelativePathSample.py

import sys
import os

targetFile = "C:/SampleDir/Dir B/Sub Dir B/Target B/TargetModule.py"

if os.path.exists(targetFile): # Safety check

    reldirFilePath = os.path.relpath(targetFile) # Relative file path wrt current directory
    print('Relative File Path: '+ reldirFilePath)
    reldirPath = os.path.dirname(reldirFilePath) # Directory of relative file path
    print('Relative Directory Path: '+ reldirPath)

    sys.path.insert(0, reldirPath) # Add relative path to Pythonpath temporarily 

    from TargetModule import someClass # Import a class from Target module

    a = someClass(2) # Example
    a.outputProperty()

Here’s what I got as output

Relative File Path: ..\..\..\Dir B\Sub Dir B\Target B\TargetModule.py
Relative Directory Path: ..\..\..\Dir B\Sub Dir B\Target B
2

Code in Action (Just in case you don’t trust me! 🙂 )

Python path.relPath in action

Do you know?… We have solved our problem!

I hope you liked this tutorial and the way I explained how to find relative path using path.relPath

Feel free to comment. Cheers!