Which is more Pythonic? (was: Detecting Binary content in files)

bieffe62 at gmail.com bieffe62 at gmail.com
Wed Apr 1 18:31:44 CEST 2009


On Apr 1, 5:10 pm, John Posner <jjpos... at snet.net> wrote:
> Dennis Lee Bieber presented a code snippet with two consecutive statements
> that made me think, "I'd code this differently". So just for fun ... is
> Dennis's original statement or my "_alt" statement more idiomatically
> Pythonic? Are there even more Pythonic alternative codings?
>
>    mrkrs = [b for b in block
>      if b > 127
>        or b in [ "\r", "\n", "\t" ]       ]
>
>    mrkrs_alt1 = filter(lambda b: b > 127 or b in [ "\r", "\n", "\t" ],
> block)
>    mrkrs_alt2 = filter(lambda b: b > 127 or b in list("\r\n\t"), block)
>

Never tested my 'pythonicity', but I would do:

def test(b) : b > 127 or b in r"\r\n\t"
mrkrs = filter( test, block )

Note: before starting to study haskell, I would probably have used the
list comprehension. Still can't stand anonimous functions though.



> (Note: Dennis's statement converts a string into a list; mine does not.)
>
> ---
>
>    binary = (float(len(mrkrs)) / len(block)) > 0.30
>
>    binary_alt = 1.0 * len(mrkrs) / len(block) > 0.30
>

I believe now one should do (at least on new code):

from __future__ import division # not needed for python 3.0
binary = ( len( mrks) / len (blocks) ) > 3.0

In the past, I often used the * 1.0 trick, but nevertheless believe
that it is better
using explicit cast.

> -John
>


Ciao
-----
FB



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