Python Cookbook 2Nd Edition Jun 1002005 [Electronic resources] نسخه متنی

Recipe 2.19. Finding Files Given a Search Path and a Pattern

Credit: Bill McNeill, Andrew Kirkpatrick

Problem

Given a search path (i.e., a string of directories with a separator
in between), you need to find all files along the path whose names
match a given pattern.

Solution

Basically, you need to loop over the directories in the given search
path. The loop is best encapsulated in a generator:

import glob, os
def all_files(pattern, search_path, pathsep=os.pathsep):
"" Given a search path, yield all files matching the pattern. ""
for path in search_path.split(pathsep):
for match in glob.glob(os.path.join(path, pattern)):
yield match

Discussion

One nice thing about generators is that you can easily use them to
obtain just the first item, all items, or anything in between. For
example, to print the first file matching '*.pye'
along your environment's PATH:

print all_files('*.pye', os.environ['PATH']).next( )

To print all such files, one per line:

for match in all_files('*.pye', os.environ['PATH']):
print match

To print them all at once, as a list:

print list(all_files('*.pye', os.environ['PATH']))

I have also wrapped around this all_files function a
main script to show all of the files with a given name along my
PATH. Thus I can see not only which one will
execute for that name (the first one), but also which ones are
"shadowed" by that first one:

if _ _name_ _ == '_ _main_ _':
import sys
if len(sys.argv) != 2 or sys.argv[1].startswith('-'):
print 'Use: %s <pattern>' % sys.argv[0]
sys.exit(1)
matches = list(all_files(sys.argv[1], os.environ['PATH']))
print '%d match:' % len(matches)
for match in matches:
print match

See Also

Recipe 2.18 for a simpler
approach to find the first file with a specified name along the path;
Library Reference and Python in a
Nutshell docs for modules os and
glob.