brock@montreat:~$ python3
Python 3.6.7 (default, Oct 22 2018, 11:32:17) 
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> import stat
>>> dir_name = '/var/tmp/csci431'
>>> file_list = os.listdir(dir_name)
>>> file_list
['dir2', 'dir3', 'here', 'random1', 'passwd', 'nothing', 'dir1', 'random2', 'a']
>>> full_file_list = [os.path.join(dir_name, x) for x in file_list]
>>> full_file_list
['/var/tmp/csci431/dir2', '/var/tmp/csci431/dir3', '/var/tmp/csci431/here', '/var/tmp/csci431/random1', '/var/tmp/csci431/passwd', '/var/tmp/csci431/nothing', '/var/tmp/csci431/dir1', '/var/tmp/csci431/random2', '/var/tmp/csci431/a']
>>> a_file = full_file_list[3]
>>> print(a_file)
/var/tmp/csci431/random1
>>> a_dir = full_file_list[0]
>>> print(a_dir)
/var/tmp/csci431/dir2
>>> os.stat(a_file)
os.stat_result(st_mode=33188, st_ino=6687272, st_dev=2066, st_nlink=1, st_uid=10000, st_gid=100, st_size=1000000, st_atime=1550242725, st_mtime=1550242725, st_ctime=1550242725)
>>> os.stat(a_dir)
os.stat_result(st_mode=16841, st_ino=6687110, st_dev=2066, st_nlink=2, st_uid=1000, st_gid=100, st_size=4096, st_atime=1550242886, st_mtime=1550242886, st_ctime=1550243438)
>>> os.stat(a_file).st_size
1000000
>>> os.stat(a_file).st_mode
33188
>>> oct(os.stat(a_file).st_mode)
'0o100644'
>>> oct(os.stat(a_dir).st_mode)
'0o40711'
>>> os.stat(a_dir).st_mode
16841
>>> stat.S_ISDIR(os.stat(a_dir).st_mode)
True
>>> stat.S_ISREG(os.stat(a_dir).st_mode)
False
>>> full_reg_list = [os.path.join(dir_name, x) for x in full_file_list

... ...          if stat.S_ISREG(os.stat(x).st_mode)]
>>> full_reg_list = [os.path.join(dir_name, x)
...            for x in full_file_list
...            if stat.S_ISREG(os.stat(x).st_mode)]
>>> full_reg_list
['/var/tmp/csci431/random1', '/var/tmp/csci431/passwd', '/var/tmp/csci431/random2']
>>> full_dir_list = [os.path.join(dir_name, x)
...            for x in full_file_list
...            if stat.S_ISDIR(os.stat(x).st_mode)]
>>> full_dir_list
['/var/tmp/csci431/dir2', '/var/tmp/csci431/dir3', '/var/tmp/csci431/here', '/var/tmp/csci431/nothing', '/var/tmp/csci431/dir1', '/var/tmp/csci431/a']
>>> os.access(full_dir_list[0], os.X_OK)
True
>>> os.access(full_dir_list[1], os.X_OK)
False
>>> os.access(full_dir_list[2], os.X_OK)
True
>>> full_dir_list = [f for f in full_dir_list
...                          if os.access(f, os.X_OK)]
>>> full_dir_list
['/var/tmp/csci431/dir2', '/var/tmp/csci431/here', '/var/tmp/csci431/nothing', '/var/tmp/csci431/dir1', '/var/tmp/csci431/a']
>>> full_dir_list
['/var/tmp/csci431/dir2', '/var/tmp/csci431/dir3', '/var/tmp/csci431/here', '/var/tmp/csci431/nothing', '/var/tmp/csci431/dir1', '/var/tmp/csci431/a']

>>> full_file_list
['/var/tmp/csci431/dir2', '/var/tmp/csci431/dir3', '/var/tmp/csci431/here', '/var/tmp/csci431/random1', '/var/tmp/csci431/passwd', '/var/tmp/csci431/nothing', '/var/tmp/csci431/dir1', '/var/tmp/csci431/random2', '/var/tmp/csci431/a']
>>> 
>>> full_reg_list
['/var/tmp/csci431/random1', '/var/tmp/csci431/passwd', '/var/tmp/csci431/random2']