Brace expansion in python glob

问题:

I have python 2.7 and am trying to issue:

glob('{faint,bright*}/{science,calib}/chip?/')

I obtain no matches, however from the shell echo {faint,bright*}/{science,calib}/chip? gives:

faint/science/chip1 faint/science/chip2 faint/calib/chip1 faint/calib/chip2 bright1/science/chip1 bright1/science/chip2 bright1w/science/chip1 bright1w/science/chip2 bright2/science/chip1 bright2/science/chip2 bright2w/science/chip1 bright2w/science/chip2 bright1/calib/chip1 bright1/calib/chip2 bright1w/calib/chip1 bright1w/calib/chip2 bright2/calib/chip1 bright2/calib/chip2 bright2w/calib/chip1 bright2w/calib/chip2

What is wrong with my expression?

回答1:

Since {} aren't part glob() in Python, what you probably want is something like

import os
import re

...

match_dir = re.compile('(faint|bright.*)/(science|calib)(/chip)?')
for dirpath, dirnames, filenames = in os.walk("/your/top/dir")
    if match_dir.search(dirpath):
        do_whatever_with_files(dirpath, files)
        # OR
        do_whatever_with_subdirs(dirpath, dirnames)

回答2:

{..} is known as brace expansion, and is a separate step applied before globbing takes place.

It's not part of globs, and not supported by the python glob function.

回答3:

Try https://pypi.python.org/pypi/braceexpand

pip install braceexpand

Demo:

>>> from braceexpand import braceexpand

# Integer range
>>> list(braceexpand('item{1..3}'))
['item1', 'item2', 'item3']

# Nested patterns
>>> list(braceexpand('python{2.{5..7},3.{2,3}}'))
['python2.5', 'python2.6', 'python2.7', 'python3.2', 'python3.3']

回答4:

As that other guy pointed out, Python doesn't support brace expansion directly. But since brace expansion is done before the wildcards are evaluated, you could do that yourself, e.g.,

result = glob('{faint,bright*}/{science,calib}/chip?/')

becomes

result = [
    f 
    for b in ['faint', 'bright*'] 
    for s in ['science', 'calib'] 
    for f in glob('{b}/{s}/chip?/'.format(b=b, s=s))
]