Open file in a relative location in Python

Suppose my python code is executed a directory called main and the application needs to access main/2091/data.txt.

how should I use open(location)? what should the parameter location be?

I found that below simple code will work.. does it have any disadvantages?

file = "\2091\sample.txt"
path = os.getcwd()+file
fp = open(path, 'r+');

With this type of thing you need to be careful what your actual working directory is. For example, you may not run the script from the directory the file is in. In this case, you can't just use a relative path by itself.

If you are sure the file you want is in a subdirectory beneath where the script is actually located, you can use __file__ to help you out here. __file__ is the full path to where the script you are running is located.

So you can fiddle with something like this:

import os
script_dir = os.path.dirname(__file__) #<-- absolute dir the script is in
rel_path = "2091/data.txt"
abs_file_path = os.path.join(script_dir, rel_path)

This code works fine:

import os


def readFile(filename):
    filehandle = open(filename)
    print filehandle.read()
    filehandle.close()



fileDir = os.path.dirname(os.path.realpath('__file__'))
print fileDir

#For accessing the file in the same folder
filename = "same.txt"
readFile(filename)

#For accessing the file in a folder contained in the current folder
filename = os.path.join(fileDir, 'Folder1.1/same.txt')
readFile(filename)

#For accessing the file in the parent folder of the current folder
filename = os.path.join(fileDir, '../same.txt')
readFile(filename)

#For accessing the file inside a sibling folder.
filename = os.path.join(fileDir, '../Folder2/same.txt')
filename = os.path.abspath(os.path.realpath(filename))
print filename
readFile(filename)

I created an account just so I could clarify a discrepancy I think I found in Russ's original response.

For reference, his original answer was:

import os
script_dir = os.path.dirname(__file__)
rel_path = "2091/data.txt"
abs_file_path = os.path.join(script_dir, rel_path)

This is a great answer because it is trying to dynamically creates an absolute system path to the desired file.

Cory Mawhorter noticed that __file__ is a relative path (it is as well on my system) and suggested using os.path.abspath(__file__). os.path.abspath, however, returns the absolute path of your current script (i.e. /path/to/dir/foobar.py)

To use this method (and how I eventually got it working) you have to remove the script name from the end of the path:

import os
script_path = os.path.abspath(__file__) # i.e. /path/to/dir/foobar.py
script_dir = os.path.split(script_path)[0] #i.e. /path/to/dir/
rel_path = "2091/data.txt"
abs_file_path = os.path.join(script_dir, rel_path)

The resulting abs_file_path (in this example) becomes: /path/to/dir/2091/data.txt

It depends on what operating system you're using. If you want a solution that is compatible with both Windows and *nix something like:

from os import path

file_path = path.relpath("2091/data.txt")
with open(file_path) as f:
    <do stuff>

should work fine.

The path module is able to format a path for whatever operating system it's running on. Also, python handles relative paths just fine, so long as you have correct permissions.

Edit:

As mentioned by kindall in the comments, python can convert between unix-style and windows-style paths anyway, so even simpler code will work:

with open("2091/data/txt") as f:
    <do stuff>

That being said, the path module still has some useful functions.

I spend a lot time to discover why my code could not find my file running Python 3 on the Windows system. So I added . before / and everything worked fine:

import os

script_dir = os.path.dirname(__file__)
file_path = os.path.join(script_dir, './output03.txt')
print(file_path)
fptr = open(file_path, 'w')

Try this:

from pathlib import Path

data_folder = Path("/relative/path")
file_to_open = data_folder / "file.pdf"

f = open(file_to_open)

print(f.read())

Python 3.4 introduced a new standard library for dealing with files and paths called pathlib. It works for me!

Code:

import os
script_path = os.path.abspath(__file__) 
path_list = script_path.split(os.sep)
script_directory = path_list[0:len(path_list)-1]
rel_path = "main/2091/data.txt"
path = "/".join(script_directory) + "/" + rel_path

Explanation:

Import library:

import os

Use __file__ to attain the current script's path:

script_path = os.path.abspath(__file__)

Separates the script path into multiple items:

path_list = script_path.split(os.sep)

Remove the last item in the list (the actual script file):

script_directory = path_list[0:len(path_list)-1]

Add the relative file's path:

rel_path = "main/2091/data.txt

Join the list items, and addition the relative path's file:

path = "/".join(script_directory) + "/" + rel_path

Now you are set to do whatever you want with the file, such as, for example:

file = open(path)

import os
def file_path(relative_path):
    dir = os.path.dirname(os.path.abspath(__file__))
    split_path = relative_path.split("/")
    new_path = os.path.join(dir, *split_path)
    return new_path
    
with open(file_path("2091/data.txt"), "w") as f:
    f.write("Powerful you have become.")

Python just passes the filename you give it to the operating system, which opens it. If your operating system supports relative paths like main/2091/data.txt (hint: it does), then that will work fine.

You may find that the easiest way to answer a question like this is to try it and see what happens.

Not sure if this work everywhere.

I'm using ipython in ubuntu.

If you want to read file in current folder's sub-directory:

/current-folder/sub-directory/data.csv

your script is in current-folder simply try this:

import pandas as pd
path = './sub-directory/data.csv'
pd.read_csv(path)

If the file is in your parent folder, eg. follower.txt, you can simply use open('../follower.txt', 'r').read()

When I was a beginner I found these descriptions a bit intimidating. As at first I would try For Windows

f= open('C:\Users\chidu\Desktop\Skipper New\Special_Note.txt','w+')
print(f) 

and this would raise an syntax error. I used get confused alot. Then after some surfing across google. found why the error occurred. Writing this for beginners

It's because for path to be read in Unicode you simple add a \ when starting file path

f= open('C:\\Users\chidu\Desktop\Skipper New\Special_Note.txt','w+')
print(f)

And now it works just add \ before starting the directory.

Get the path of the parent folder, then os.join your relative files to the end.

# get parent folder with `os.path`
import os.path
BASE_DIR = os.path.dirname(os.path.abspath(__file__))
file = "config.yaml"
final_path = os.path.join(BASE_DIR, file)

# get parent folder with `pathlib`'s Path
from pathlib import Path
BASE_DIR = Path(__file__).absolute().parent
file = "config.yaml"
final_path = BASE_DIR / file

In Python 3.4 (PEP 428) the pathlib was introduced, allowing you to work with files in an object oriented fashion:

from pathlib import Path

working_directory = Path(os.getcwd())
path = working_directory / "2091" / "sample.txt"
with path.open('r+') as fp:
    # do magic

The with keyword will also ensure that your resources get closed properly, even if you get something goes wrong (like an unhandled Exception, sigint or similar)