Saketh wrote:
> Hi everyone:
>
> I'm using "translation" in the sense of string.maketrans here.
>
> I am trying to efficiently compare if two string translations
> "conflict" -- that is, either they differently translate the same
> letter, or they translate two different letters to the same one. Here
> are some examples:
>
> # no conflict - equal
> t1 = Translation('ab', 'cd')
> t2 = Translation('ab', 'cd')
>
> # no conflict - inverses
> t1 = Translation('ab', 'cd')
> t2 = Translation('cd', 'ab')
>
> # conflict - same key, different value
> t1 = Translation('ab', 'cd')
> t2 = Translation('ab', 'ce')
>
> # conflict - different key, same value
> t1 = Translation('ab', 'cd')
> t2 = Translation('xy', 'cd')
>
> This conflict-checking is the bottleneck of my program, and the
> obvious way to implement it -- looping through the translations and
> explicitly checking for the above conditions -- is much slower than
> I'd like.
>
> Is there a more efficient, Pythonic way of checking if two
> translations conflict?
Is the following a correct interpretation of your requirements?
class Translation(object):
def __init__(self, from_, to):
self.from_ = set(from_)
self.to_ = set(to)
self.map = dict(zip(from_, to))
def conflict(t1, t2):
a = t1.from_
b = t2.from_
ma = t1.map
mb = t2.map
if any(ma[x] != mb[x] for x in a & b):
return True
c = set(ma[x] for x in a - b)
d = set(mb[x] for x in b - a)
return c & d
Peter
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