[Tutor] Masking operation

Rich Lovely roadierich at googlemail.com
Thu Oct 15 17:58:34 CEST 2009

2009/10/15 Kent Johnson <kent37 at tds.net>:
> On Wed, Oct 14, 2009 at 10:48 PM, Wayne <srilyk at gmail.com> wrote:
>> Using zip is redundant for me, this is what my function looks like now:
>> def crypt(msg, mask):
>>     m = itertools.cycle(mask)
>>     word = ''
>>     for l in msg:
>>         word += chr(ord(l) ^ ord(m.next()))
>>     return word
> With zip() and a generator expression you can write it as
> def crypt(msg, mask):
>  mask = itertools.cycle(mask)
>  chars = zip(msg, mask)
>  return ''.join(chr(ord(l) ^ ord(m)) for l, m in chars)
> which could be reduced to a one-liner if you like.
> Kent

And that's why itertools is probably my favourite module.

For extra jollies, you can define it as a lambda:

crypt = lambda msg, mask: "".join(chr(ord(l)^ord(m)) for l,m in
zip(msg, itertools.cycle(mask)))

But that's maybe going a little over the top, unless we're entering an
obfuscated code contest.

Rich "Roadie Rich" Lovely

There are 10 types of people in the world: those who know binary,
those who do not, and those who are off by one.

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