How to Use Python os.path.join
You may have gotten caught up in a path labyrinth when you’re working with files in Python.
To work with files, you need to specify the directory in which a file appears. This is easier than it sounds. If you don’t specify the right path, your program will not work.
In this guide, we’re going to talk about os.path.join. This is a method that combines components of a file path into a complete path. We’ll walk through two examples to help you get started with this method.
What is in a File Path?
A file path refers to a sequence of file and folder names that take you to a certain place on your computer’s operating system (OS).
Let’s take the following path as an example:
This path takes us to a folder called “tutorials”. If we wanted to access a particular file or directory in this folder, we could point to it using its file name:
You can write these file paths manually in Python. Doing so can be impractical. That’s where os.path.join comes in.
What is os.path.join?
os.path.join combines pathnames into one complete path. This means that you can merge multiple parts of a path into one, instead of hard-coding every path name manually.
To use this function, you need to import the os library into your code:
Now that you’ve imported an os library, you are ready to go! The os.path.join function accepts a list of paths that you want to merge into one:
path = os.path.join("/Users/James/tutorials", "index.html") print(path)
This code returns: /Users/James/tutorials/index.html. The os.path.join method continues from the absolute path component we have specified (“/Users/James/tutorials”) and the joining adds index.html to the end of the existing path.
Handily, the os.path.join method inserts forward slashes (which are called “directory separators”) when they are needed. This makes it a more convenient way of combining file path names than manually concatenating them.
Let’s write a program that calculates the path of a file called “index.html” in the folder “tutorials/web/” which is inside our current working directory.
We’ll start by importing the os library:
Next, we are going to get our current working directory so that we can add our file path name to it:
cwd = os.getcwd()
This returns our current working directory, which is /Users/James/tutorials. The “tutorials” folder is inside our user’s home directory. We can use this information to add “tutorials/web” to the end of our working directory:
web_tutorials = os.path.join(cwd, "tutorials/web") print(web_tutorials)
This code returns: /Users/James/tutorials/web. Our code has combined our pathname components into one. A forward slash (“/”) has been added between our path names.
Using os.path.join to List Files
Let’s use the os.path.join method to return the full file paths of all the files in a folder. We’re going to list all the files in the “Desktop” folder.
We’ll start by importing the os library and defining the directory that we want to search:
import os cwd = os.getcwd() desktop = os.path.join(cwd, "Desktop")
This code generates the file path for the Desktop folder relative to our current working directory. Next, we can use os.listdir() to retrieve a list of all the files in this folder:
files = os.listdir(desktop)
This method returns a list of the names of all files that appear in the Desktop folder. It does not include the paths of the files. Now that we have this list of files, we can print them all to the console. We’re going to print the full file path for each file using os.path.join and a for loop:
for f in files: print(os.path.join(desktop, f))
This code loops through all the files in the Desktop folder. It merges the name of each file with the path name of the Desktop folder. Our code returns:
/Users/James/Desktop/.DS_Store /Users/James/Desktop/Notes.md /Users/James/Desktop/To-dos.md
There are three files on my desktop: .DS_Store, Notes.md, and To-dos.md. We used
os.path.join() to generate the full paths of each file.
The os.path.join method combines components in a pathname to create a full path name.
This method makes it easy to combine two or more components of a pathname. Os.path.join automatically inserts forward slashes (“/”) into the pathname when needed.
Now you’re ready to start using the os.path.join method like an expert Python developer!