In [108]: os.mkdir('newdir') # make new dir
In [140]: p = os.path.abspath('newdir')

In [141]: p
Out[141]: '/media/sagarkar10/sdrive/programing/python/SciPy/scipy-notebook/newdir'

## here 'newdir' is also a directory with a file inside

In [143]: os.path.dirname(p)
Out[143]: '/media/sagarkar10/sdrive/programing/python/SciPy/scipy-notebook'

## but os.path.dirname() dont show it under directory it treats as if its a file and till the last '/' is the directory
and also 

In [145]: os.path.basename(p)
Out[145]: 'newdir'

## basename shows it