# -*- coding: Windows-1251 -*-
'''
Relative path from one directory to another without explicit string functions (unix only)
Function deal with Unix paths (root: "/"), Windows systems are not supported (root: "C:\").
'''
__author__ = 'Denis Barmenkov <denis.barmenkov@gmail.com>'
__source__ = 'http://code.activestate.com/recipes/577356'
import os
if os.name == 'nt':
raise ValueError, 'dos/windows paths unsupported in this version'
def relative_path(base, target):
def split_path(path):
res = list()
while 1:
path, basename = os.path.split(path)
if path == os.sep and basename == '':
# root reached
break
res.insert(0, basename)
if path == '':
break
return res
# check for absolute paths
if not base.startswith(os.sep):
raise ValueError, 'base must be absolute: %s' % base
if not target.startswith(os.sep):
raise ValueError, 'target must be absolute: %s' % target
base_parts = split_path(base)
target_parts = split_path(target)
while len(base_parts) > 0 and \
len(target_parts) > 0 and \
base_parts[0] == target_parts[0]:
base_parts.pop(0)
target_parts.pop(0)
rel_parts = ['..'] * len(base_parts)
rel_parts.extend(target_parts)
return os.path.join(*rel_parts)
if __name__ == '__main__':
base = os.sep + os.path.join('a', 'b', 'c', 'd')
target = os.sep + os.path.join('a', 'b', 'c1', 'd2')
print 'base :', base
print 'target:', target
print 'relative base->target:', relative_path(base, target)
Diff to Previous Revision
--- revision 3 2010-08-13 07:07:57
+++ revision 4 2011-04-11 13:02:32
@@ -18,9 +18,7 @@
res = list()
while 1:
path, basename = os.path.split(path)
- if basename == '':
- continue
- if path == os.sep:
+ if path == os.sep and basename == '':
# root reached
break
res.insert(0, basename)
