Character Replace Anagrams

import re

### References
#
# Functions
# ----------------------------------------------------------
# * contains() : http://stackoverflow.com/questions/14411633
# * to_dict()  : http://stackoverflow.com/questions/209840/
# * replace()  : http://stackoverflow.com/questions/6116978/
#
# Dictionary
# ----------------------------------------------------------
# * linux.txt  : http://www.cs.duke.edu/~ola/ap/linuxwords

read_dict=lambda f:[x.strip() for x in open(f,'r')]
write_dict=lambda f,l:open(f,'w').write('\n'.join(l))
split=lambda l,d:[x.strip() for x in l.split(d)]
split_list=lambda a:(a[:len(a)/2],a[len(a)/2:])
are_anagrams=lambda one,two:sorted(one.lower())==sorted(two.lower())
contains=lambda s,v:len([e in s for e in v if e in s])>0
to_dict=lambda _from,_to:dict(zip(_from,_to))

def replacement_map(ch_from, ch_to, bidirectional=False):
    if (bidirectional):
        return dict(to_dict(ch_from, ch_to).items() \
            + to_dict(ch_to, ch_from).items())
    else:
        return to_dict(ch_from, ch_to)

def combos(a,b):
    c,s = a+b,min(len(a),len(b))
    return [''.join([c[int(s*((i/(2**(s-j-1)))%2)+j)] for j in range(s)]) for i in range(2**(s))]

def opposites(a,b):
    lists = split_list(combos(a,b))
    return zip(lists[0], lists[1][::-1])

def replace(s,f,t,bi=True):
    rep = dict((re.escape(k), v) for k, v in replacement_map(f,t,bi).iteritems())
    pattern = re.compile("|".join(rep.keys()))
    return pattern.sub(lambda m: rep[re.escape(m.group(0))], s)

def replace_with(word, a, b):
    for key, val in opposites(a, b):
        if contains(word, key):
            return replace(word, key, val)
    return word

def find_anagrams(word):
    chars,is_valid = sorted(word.lower()),lambda a,b:a==sorted(b.lower())
    return filter(lambda i:is_valid(chars,i), read_dict('dictionaries/linux.txt'))

if __name__ == '__main__':
    _word,_from,_to = 'throws', 'sw', 'ne'
    #print contains(_word, _to)
    #print replace(_word, _to, _from, False)
    #print replacement_map(_to, _from, True)
    #print combos(_to, _from)
    #print opposites(_to, _from)

    print find_anagrams(replace_with(_word, _from, _to)) # ['hornet', 'throne']