[Tutor] thanks!

[Christopher Spears]

I solved the problem!  As several have pointed out, I
was providing file names not pathways.  Here is the
resulting code:

import os

def get_size(n,directory,files):
    files_of_size = {}; sizes = [];
    biggest_files = [];

    files = map(os.path.join,[directory] *
len(files),files)
    files = filter(lambda x: not os.path.isdir(x)
                   and not os.path.islink(x), files)
#Creates a list of file pathnames.

    for f in files:
       
files_of_size.setdefault(os.path.getsize(f),[]).append(f)
#Creates a dictionary where the keys are the sizes.
    
    sizes = files_of_size.keys()
    sizes.sort(); sizes.reverse();
    for s in sizes:
        biggest_files.append([files_of_size[s],s])
#Sorts keys from largest to smallest and places the
names in a
#new list in that order.

    print "in directory %s:" % directory

    try:
        while n > 0:
            print biggest_files[n-1]
            n = n - 1
    except IndexError,msg:
            print "%d is too high.  Try a smaller
number" %n

#Prints out the n largest files.

Notice I do not use a lot of functional programming. 
I have nothing against functional programming.  I just
do not undertand much of it, which is why I took this
particular approach.  Karl has pointed out several
times that if I used functional programming then my
code would be much more succinct.

Thanks!