Python relative path in package

Simple trick to work with relative paths in Python

The goal of this article is to calculate a path to a file in a folder in your project. The reason we calculate this path is that you refer to the correct location no matter where the code is installed. This is the case when you share your code with a coworker or deploy your code on a webserver e.g.

You can’t hardcode the (expected) location of the file because C:/users/mike/myproject/config/.env doesn’t exist on your machine or on the server we’re deploying to. Ideally we’d like to specify the path relative to the root folder of our project.

In this article we’ll check out a simple Python trick that allows us to refer to files relative to our project folder in a very easy way. Let’s code!

TL/DR; Check out ‘The Trick” below!

Use cases

Two quick example on where this trick comes in handy:

• Loading an environment file from e.g. /config/.env
• We have an API that receives files; the files should always be stored in data/received_audio_files for example.

Preparation

In this article we’ll set up our project structure like this:

relative_path 
- data 
-- mydata.json 
- processes
-- load_data.py

All of our code is contained in a folder called relative_path . This is the root of our projects, meaning it holds all of our code. As you can see we have two folder: the data folder that contains our target json file, and our processes folder that contains load_data.py ; the code will load the mydata.json .

Loading the data

In this part we’ll start with the most obvious way of loading mydata.json and see its flaws. Then we’ll slowly improve, ending with a method that will load it relatively. Then we’ll compile this knowledge in a simple trick that will help us in all of our future projects.

1. Absolute path

The most straight-forward method is just using an absolute path in our code.

import json
f = open(r’C:\projects\relative_path\data\mydata.json’)…

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Relative Path in Python

1. File Path in Python
2. Absolute Path
3. Relative Path

In this tutorial, we will discuss the relative path in Python.

File Path in Python

A file path specifies the location of a file in the computer. For example, C:\PythonProjects\Tutorials\Paths is the path of a file paths.py in my windows machine. Here, C:\ is the root directory, and PythonProjects , Tutorials and Paths are subdirectories. paths.py is a python script inside Paths directory inside Tutorials directory inside PythonProjects directory inside the root directory C:\ . There are two types of file paths in Python, i.e., absolute and relative paths.

Difference Between Windows, Mac, and Linux

In Windows machines, \ is used as a separator between directory names whereas, in both Linux and Mac machines, / is used as a separator. For example,

#file path in Windows rootdirectory\\subdirectory\\subsubdirectory\\filename.extension #file path in Mac and Linux rootdirectory/subdirectory/subsubdirectory/filename.extension 

In windows, there are two backslashes because each backslash needs to be escaped using another backslash. This can be managed by using os.path.join() method. This method handles the separators according to the operating system. For example,

import os pathname = os.path.join("root", "directory1", "directory2") print(pathname) 

#On Windows root\directory1\directory2 #On Mac and Linux root/directory1/directory2 

This tutorial would contain \ as the separator to give the examples in Windows. We will use the following file hierarchy and set C:\PythonProjects\Tutorials\Paths to be the current working directory.

Current Working Directory

The current working directory or cwd in short is the directory from which the program is being executed. You can get the current working directory of the particular file by os.getcwd() method.

C:\PythonProjects\Tutorials\Paths 

The current working directory can also be changed at runtime using the os.chdir() method).

import os print("Old cwd = " + os.getcwd()) os.chdir("C:\\PythonProjects\\Tutorials") print("New cwd = " + os.getcwd()) 

Old cwd = C:\PythonProjects\Tutorials\Paths New cwd = C:\PythonProjects\Tutorials 

Absolute Path

An absolute path of a file is the complete path from the root directory to that particular file. For example, C:\PythonProjects\Tutorials\Paths\paths.py is the absolute path of paths.py file.

We can get the absolute path of the current file as shown below.

import os absolutepath = os.path.abspath(__file__) print(absolutepath) 

C:\PythonProjects\Tutorials\Paths\paths.py 

Navigate to Strings Directory Using Absolute Path in Python

Navigating to a folder using the absolute path in Python is pretty easy. The only headache is that you have to know the exact names of all the directories from the root directory.

import os print("Old cwd = " + os.getcwd()) os.chdir("C:\\PythonProjects\\Tutorials\\Strings") print("New cwd = " + os.getcwd()) 

Relative Path

The absolute path is helpful, but it can become complex very soon. So, to minimize this complexity, a relative path is used. Relative path means the path of a certain file relative to the current working directory.

For example, if the current working directory is C:\PythonProjects\Tutorials , the path.py file’s relative path would be \Paths\paths.py which is shorter and easier to use than the absolute path C:\PythonProjects\Tutorials\Paths\paths.py .

The absolute path of a file remains the same everywhere, but the relative path changes depending upon the current working directory. This phenomenon is demonstrated in the following coding example.

Navigate to Strings Directory Using Relative Path in Python

If we need to access files in the Strings folder, we have to either use the complete absolute path C:\PythonProjects\Tutorials\Strings\string.py or we can do as mentioned in the following code.

import os import sys  absolutepath = os.path.abspath(__file__) print(absolutepath)  fileDirectory = os.path.dirname(absolutepath) print(fileDirectory) #Path of parent directory parentDirectory = os.path.dirname(fileDirectory) print(parentDirectory) #Navigate to Strings directory newPath = os.path.join(parentDirectory, 'Strings') print(newPath) 

C:\PythonProjects\Tutorials\Paths\paths.py C:\PythonProjects\Tutorials\Paths C:\PythonProjects\Tutorials C:\PythonProjects\Tutorials\Strings 

Maisam is a highly skilled and motivated Data Scientist. He has over 4 years of experience with Python programming language. He loves solving complex problems and sharing his results on the internet.

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