how to sort this python code alphabetically

Question

i've tried so hard to sort these code alphabetically but still not working. tis is the error message :

Traceback (most recent call last): File "D:\\Eclipse Workspace\\tugas1\\src\\h.py", line 15, in for word in set(l): TypeError: 'NoneType' object is not iterable

here the code :

from re import compile

l=compile("(\w[\w']*)").findall(open(raw_input('Input file: '),'r').read().lower()).sort()

f=open(raw_input('Output file: '),'w')

for word in set(l):

    print>>f, word, ':', '\t', l.count(word), 'kata'

f.close()

Answer 1

The problem is the .sort() . It sorts the list in place and returns None , so that is the result of the assignment. l is always None. . Do the sort separately, after all the other stuff.

l=compile("(\w[\w']*)").findall(open(raw_input('Input file: '),'r').read().lower())
l.sort()

Just BTW, there is no need to compile a regex if you're just going to use it once. No harm in doing so, though.

Answer 2

.sort() sorts the list in place. It does not return the sorted list. Because it doesn't, it default to return None .

Thus, l = None . You don't want this.

Your code should be:

from re import compile
l = compile("(\w[\w']*)")
with open(raw_input('Input file: '),'r') as myfile:
    content = myfile.read().lower()
    l = l.findall(content)
    l.sort() # Notice how we don't assign it to anything

...

Sparse is better than dense . Don't try to put everything in one line