Oserror: [Errno 20]

[Scott David Daniels]

Peter Hansen wrote:
> k r fry wrote:
>> Hi, I am new to this list and also programming with python.
>> I have an error: oserror [errno 20] not a directory "katiescint.py"
>> The piece of code causing the problem is:
>> [code]
>>
>> for subdir in os.listdir(DATADIR):              #loop through list of 
>> strings
>>
>>      file=FITS.Read(DATADIR+'/'+subdir+'/flux.fits')     #opens 
>> flux.fits file and reads
> 
> os.listdir() returns a list of all files and directories inside the 
> directory specified (DATADIR), so you can't assume that "subdir" is 
> always going to be a directory.  Use os.path.isdir() to confirm that it 
> is and ignore those items for which that function returns False.

I'd guess you might want to go with something like:

     for root, dirs, files in os.walk(DATADIR):
         if 'flux.fits' in files:
             file = FITS.Read(os.path.join(root, 'flux.fits'))

read up on:
     os.path.join
and
     os.walk

The previous code will do lots of recursive walking in a deeply nested
directory structure.  If you only want to look at single-level subdirs,
you could either do:

     root, dirs, files = iter(os.walk(DATADIR)).next()
     for subdir in dirs:
         file = FITS.Read(os.path.join(root, subdir, 'flux.fits'))

or:
     for root, dirs, files in os.walk(DATADIR):
         if 'flux.fits' in files:
             file = FITS.Read(os.path.join(root, 'flux.fits'))
         if root != DATADIR:
             del dirs[:]  # Stop recursing after the first descent)

depending on whether you know 'flux.fits' should be there or
you only want to work on subdirs where it is in the directory.

-Scott David Daniels
scott.daniels at acm.org