python - os.walk 目录名中的空列表是什么？

Question

使用 python 3.5 时 os.walk()并查看 dirname 输出，我得到了很多空列表(返回 [ ] )。我不知道为什么。

import os
tdir = '/home/pontiac/testdir'

gen0 = os.walk(tdir)
print(next(gen0)[1])
print(next(gen0)[1])

gen1 = os.walk(tdir)

for ea in gen1:
    print(ea[1])

输出:

['t2', 't1']

[]

['t2', 't1']

[]

[]

Answer 1

引自 Python Documentation :

os.walk(top, topdown=True, onerror=None, followlinks=False)
Generate the file names in a directory tree by walking the tree either top-down or bottom-up. For each directory in the tree rooted at directory top (including top itself), it yields a 3-tuple (dirpath, dirnames, filenames).

dirpath is a string, the path to the directory. dirnames is a list of the names of the subdirectories in dirpath (excluding '.' and '..'). filenames is a list of the names of the non-directory files in dirpath. Note that the names in the lists contain no path components. To get a full path (which begins with top) to a file or directory in dirpath, do os.path.join(dirpath, name).

自 testdir只有两个空目录 t1和 t2 ，所以你会得到:

>>> import os
>>> t = '/home/pontiac/testdir'
>>> for root, dirs, files in os.walk(t):
    print root, dirs, files


/home/testdir ['t1', 't2'] []
# ^rootdir     ^dirs list  ^files in rootdir 
/home/testdir/t1 [] []
/home/testdir/t2 [] []