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Re: Fun python 3.2 one-liner

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  Re: Fun python 3.2 one-liner harrismh777 <harrismh777@charter.net> - 2011-03-29 14:00 -0500
    Re: Fun python 3.2 one-liner gb <gb@cabiate.it> - 2011-04-04 22:09 +0200
      Re: Fun python 3.2 one-liner Chris Angelico <rosuav@gmail.com> - 2011-04-05 07:46 +1000
        Re: Fun python 3.2 one-liner Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2011-04-05 10:16 +1200
          Re: Fun python 3.2 one-liner Chris Angelico <rosuav@gmail.com> - 2011-04-05 08:45 +1000
          Re: Fun python 3.2 one-liner Emile van Sebille <emile@fenx.com> - 2011-04-04 15:46 -0700
        Re: Fun python 3.2 one-liner Giacomo Boffi <giacomo.boffi@polimi.it> - 2011-04-05 07:36 +0200

#2171 — Re: Fun python 3.2 one-liner

Raymond Hettinger wrote:
> almost-normally-yours,
>
> Raymond

thanks ... interesting

Seriously, these little one liners teach me more about the python 
language in less time than *all* of the books I'm trying to digest right 
now.  The toughest part of learning python is learning about what's 
available so as not to reinvent the proverbial wheel...

thanks again... fun.

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#2591

harrismh777 <harrismh777@charter.net> writes:

> Seriously, these little one liners teach me more about the python
> language in less time than [...]

def f(x,n,w): return x if n==1 else\
    (lambda x0=f(x[::2],n/2,w[::2]),\
            x1=f(x[1::2],n/2,w[::2]): reduce(lambda a,b: a+b ,\
                                      zip(*[(x0[k]+w[k]*x1[k],\
                                             x0[k]-w[k]*x1[k])\
                                             for k in range(n/2)])))()

it was a joke of sort played on it.comp.lang.python

[thanks to marco (zip(*...))  and antonio (lambda with default
arguments)]

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#2602

On Tue, Apr 5, 2011 at 6:09 AM, gb <gb@cabiate.it> wrote:
> harrismh777 <harrismh777@charter.net> writes:
>
>> Seriously, these little one liners teach me more about the python
>> language in less time than [...]
>
> def f(x,n,w): return x if n==1 else\
>    (lambda x0=f(x[::2],n/2,w[::2]),\
>            x1=f(x[1::2],n/2,w[::2]): reduce(lambda a,b: a+b ,\
>                                      zip(*[(x0[k]+w[k]*x1[k],\
>                                             x0[k]-w[k]*x1[k])\
>                                             for k in range(n/2)])))()
>
> it was a joke of sort played on it.comp.lang.python

(Remind me how it is that Python code is more readable than line noise
or Perl code?)

What sort of parameters does this take? So far all I can figure out is
that n is an integer and x and w are sliceables, but I'm not sure
whether x and w should be strings or arrays.

ChrisA

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#2609

Chris Angelico wrote:

> (Remind me how it is that Python code is more readable than line noise
> or Perl code?)

Crazy thought: I wonder if Perl programmers have "multi
line Perl" competitions where they laugh their heads off
at how readable the code is, and how nobody in their
right mind would ever write Perl code that way?-)

-- 
Greg

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#2612

On Tue, Apr 5, 2011 at 8:16 AM, Gregory Ewing
<greg.ewing@canterbury.ac.nz> wrote:
> Chris Angelico wrote:
>
> Crazy thought: I wonder if Perl programmers have "multi
> line Perl" competitions where they laugh their heads off
> at how readable the code is, and how nobody in their
> right mind would ever write Perl code that way?-)

Ha!! Okay, now I have to explain to my fellow bus passengers what it
is that I just cracked up laughing at...

You know what? I don't think I can.

I do like readable code, but quite a few of my favorite language
features are the ones commonly (ab)used to make unreadable code. C's
?: operator, Pike's interpretation of || for defaults, Python's lambda
functions... all great ways to shorten your code, but so easily used
for evil.

I think I like things that can be used for evil.

ChrisA

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#2613

On 4/4/2011 3:16 PM Gregory Ewing said...
> Chris Angelico wrote:
>
>> (Remind me how it is that Python code is more readable than line noise
>> or Perl code?)
>
> Crazy thought: I wonder if Perl programmers have "multi
> line Perl" competitions where they laugh their heads off
> at how readable the code is, and how nobody in their
> right mind would ever write Perl code that way?-)
>

I don't know if I should be laughing or nodding in agreement... :)

Emile

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#2629

Chris Angelico <rosuav@gmail.com> writes:

>> def f(x,n,w): return x if n==1 else\
>>    (lambda x0=f(x[::2],n/2,w[::2]),\
>>            x1=f(x[1::2],n/2,w[::2]): reduce(lambda a,b: a+b ,\
>>                                      zip(*[(x0[k]+w[k]*x1[k],\
>>                                             x0[k]-w[k]*x1[k])\
>>                                             for k in range(n/2)])))()

> What sort of parameters does this take? So far all I can figure out
> is that n is an integer and x and w are sliceables, but I'm not sure
> whether x and w should be strings or arrays.

def direct_fft(x,n):
  return f(x,n,[exp(-2*pi*1j*k/n) for k in range(n/2)]) 
def inverse_fft(x,n):
  return [x/n for x in f(x,n,[exp(+2*pi*1j*k/n) for k in range(n/2)])] 
-- 
le mie sacrosante questioni di principio
          VS     gli sciocchi puntigli di quel cretino del mio vicino

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