Generating subsets of a permuted wordlist in Python

I have a list of words and I need to generate all possible permutations of these, with one caveat.

I currently use the following code:

from itertools import permutations

wordlist = ["word1", "word2", "word3"]

for perm in permutations(wordlist):
    print "".join(perm)

which gives the ou开发者_如何学Gotput:

word1word2word3
word1word3word2
...
word3word2word1

However I also need it to print subsets these words, such as:

word1    
word1word2
word2word1
...

But I haven't the slightest idea how to do this. Where do I begin? What should I read?

Edited:

from itertools import permutations

xlist = ["word1", "word2", "word3"]

for n in range(1, len(xlist)+1):
    for perm in permutations(xlist, n):
        print "".join(perm)

Edit: output:

word1
word2
word3
word1word2
word1word3
word2word1
word2word3
word3word1
word3word2
word1word2word3
word1word3word2
word2word1word3
word2word3word1
word3word1word2
word3word2word1

Here is a more complete implementation with file I/O. Thanks Steve, I based myself on your answer. This code, unlike other posts, was written for Python 3.3.4

from itertools import permutations
import os

# GET FILE
script_dir = os.path.dirname(os.path.realpath(__file__))
wordlist_rel_path = "wordlist.txt"
wordlist_abs_file_path = os.path.join(script_dir, wordlist_rel_path)

# READ WORD LIST FROM FILE
word_list = []
print ("\ninput file is:", wordlist_abs_file_path,"\n")
with open(wordlist_abs_file_path) as wordlist:
     for line in wordlist:
         word_list.append(line.rstrip())

# PRINT INPUT LIST
print ("input list contains:")
print(word_list,"\n")

# GENERATE POWERSET
powerset_list = []
print ("output list is:")
for n in range(1, len(word_list)+1):
     for perm in permutations(word_list, n):
         powerset_list.append( "".join(perm) )
print(powerset_list)

# WRITE LIST TO FILE
powerset_rel_path = "powerset.txt"
powerset_abs_file_path = os.path.join(script_dir, powerset_rel_path)
powerset_abs_file = open(powerset_abs_file_path, 'w')
for item in powerset_list:
     powerset_abs_file.write("%s\n" % item)
powerset_abs_file.close()