SaltyCrane Blog

Notes on Python, Django, and web development on Ubuntu Linux

os.path.relpath() source code for Python 2.5

Date: March 31, 2010 | Tags: files_directories, python | 1 Comment

Today I needed to use the os.path.relpath() function. However this function was introduced in Python 2.6 and I am using Python 2.5 for my project. Luckily, James Gardner has written a version that works with Python 2.5 (on Posix systems (which mine is (Linux))). His relpath function is part of his BareNecessities package. You can view the documentation here.

Here is James Gardner's relpath function:

from posixpath import curdir, sep, pardir, join

def relpath(path, start=curdir):
    """Return a relative version of a path"""
    if not path:
        raise ValueError("no path specified")
    start_list = posixpath.abspath(start).split(sep)
    path_list = posixpath.abspath(path).split(sep)
    # Work out how much of the filepath is shared by start and path.
    i = len(posixpath.commonprefix([start_list, path_list]))
    rel_list = [pardir] * (len(start_list)-i) + path_list[i:]
    if not rel_list:
        return curdir
    return join(*rel_list)

How to remove ^M characters from a file with Python — posted 2011-10-03
Options for listing the files in a directory with Python — posted 2010-04-19
Monitoring a filesystem with Python and Pyinotify — posted 2010-04-09
A hack to copy files between two remote hosts using Python — posted 2010-02-08
Iterating over lines in multiple Linux log files using Python — posted 2010-01-23

1 Comment — Comments feed for this post

#1 Pamela McA'Nulty commented on 2011-11-09:

Fixed to deal with missing posixpath functions, works in 2.4 too pam

from posixpath import curdir, sep, pardir, join, abspath, commonprefix

def relpath(path, start=curdir):
    """Return a relative version of a path"""
    if not path:
        raise ValueError("no path specified")
    start_list = abspath(start).split(sep)
    path_list = abspath(path).split(sep)
    # Work out how much of the filepath is shared by start and path.
    i = len(commonprefix([start_list, path_list]))
    rel_list = [pardir] * (len(start_list)-i) + path_list[i:]
    if not rel_list:
        return curdir
    return join(*rel_list)

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