Manipulating paths in python

Question

I am writing a python script 2.5 in Windows whose CurrentDir = C:\users\spring\projects\sw\demo753円\ver1.1011円\rev120\source my file is test.py. From this path I would like to access files in this path: C:\users\spring\projects\sw\demo753円\ver1.1011円\rev120\Common\

I tried using os.path.join but it does not work and I from the docs I understand why. So what could be the best pythonic solution for this?

currentdir = os.getcwd() 
config_file_path = os.path.join(currentdir,"\\..\\Common")

• Adam Rosenfield: Post some code. What's not working?
• Sanjay: Code snippet would be helpful in tracking down the problem.
• ThiefMaster: Why are you using an ancient python version?
• spring: @ThiefMaster My environment has a number of internal tools all based on python 2.5 so can't break it
• ThiefMaster: Sounds like those tools should be tested with 2.6/2.7 (which should be easy since those versions do not introduce many changes which might break things) instead of keeping such an old version.

Answer 1

Your problem can be solved by using os.path.join, but you're not using it properly.

currentdir = os.getcwd() 
config_file_path = os.path.join(currentdir,"\\..\\Common")

"\\..\\Common" is not a relative path, as it starts with \.

You need to join with ..\\Common, which is a relative path.

Please note that os.path.join is not a simple string concatenation function, you don't need to insert the in-between antislashes.

So fixed code would be :

config_file_path = os.path.join(currentdir,"..\\Common")

or, alternatively :

config_file_path = os.path.join(currentdir, "..", "Common")

Answer 2

from os.path import dirname, join
join(dirname(dirname(__file__)), 'Common')

should work.

• ThiefMaster: Importing everyhing into the global scope is pretty messy.
• phihag: @ThiefMaster Just importing two functions hardly counts as "everything", and makes the line look less cryptic. Of course, you can write os.path.join(os.path.dirname(os.path.dirname(__file__)), 'Common')
• ThiefMaster: In a small script you are right, but in a module with a few hundred SLOC someone won't expect join to be from os.path but rather something more generic...
• spring: For my specific problem it may work but what about if I want to access files in C:\users\spring\projects\sw\demo753円\ver1.1 ? I will have to use dirname a number of times.

Answer 3

Try this:

joined = os.path.join('C:\\users\\spring\\projects\\sw\\demo\753円\\ver1.1\011円\\rev120\\source', '..\\Common\\')
# 'C:\\users\\spring\\projects\\sw\\demo\753円\\ver1.1\011円\\rev120\\source\\..\\Common\\'
canonical = os.path.realpath(joined)
# 'C:\\users\\spring\\projects\\sw\\demo\753円\\ver1.1\011円\\rev120\\Common'

• spring: I get my current dir using os.getcwd() which returns 'C:\users\spring\projects\sw\demo753円\ver1.1011円\rev120\source' and when I try to use join I only get C:\common which is not I want
• jd.: @ThiefMaster The comment is a copy-paste from the Python interpreter. join() did not remove the ... I agree though that the path is usable as it is and the call to realpath() is completely unnecessary.
• jd.: @spring What's the output of os.path.join(os.getcwd(), '..\\Common')?
• jd.: I get `C:\users\spring\projects\sw\demo753円\ver1.1011円\rev120\source\..\Common` when I substitute your path for os.getcwd(). I don't know why we are getting different results. I'm running Python 2.7 on Windows.