Nesting Instinct

11 Responses to "Nesting Instinct"

• 
  pythonista

  March 12th, 2009, 7:55 p.m.

  You could have string values (for example) with parenthesis in them. These values would be changed.

• 
  Steve Holden

  March 12th, 2009, 7:58 p.m.

  A further reason is that you have no idea what the repr of the object looks like, since you don't even examine its type …

  One must hope nobody starts devising malicious objects with exploitive repr()s.

  Cute idea, though.

• 
  Euan Goddard

  March 12th, 2009, 8:51 p.m.

  I can't believe you had the audacity to post that! Very amusing though. Let me know when you can properly do it in 2 lines

• 
  WIll McGugan

  March 12th, 2009, 9:19 p.m.

  How about this, Euan…

  def flatten(tpl):
      return sum(map(flatten, tpl), ()) if type(tpl) is tuple else (tpl,)
      
  t= (1, (1, 2, (1, 2, 3), 3))
  print flatten(t)
  

  
  

  Not quite as concise as the the other flatten, but less of a crime against Python!

• 
  jdm

  March 12th, 2009, 9:40 p.m.

  2euan: is this “properly”?

  def flatten(tpl):
   return reduce(lambda x,y: x+flatten(y),tpl,()) if type(tpl) is tuple else (tpl,)
  

  
  
• 
  Roberto

  March 12th, 2009, 9:49 p.m.

  A safe variant of your solution, assuming the values are integers:

  def flatten(tpl):

  return tuple( map(int, repr(tpl).replace('(', ‘').replace(’)', ‘').split(’, ')) )

• 
  Roberto

  March 12th, 2009, 9:50 p.m.

  Posting again, sorry:

  def flatten(tpl):
          return tuple( map(int, repr(tpl).replace('(', '').replace(')', '').split(', ')) )
  

  
  
• 
  jdm

  March 12th, 2009, 9:52 p.m.

  oops, didn't see Will's, which is cleaner.

• 
  Paddy3118

  March 13th, 2009, 5:22 a.m.

  Since I've been glancing at the Y combinator [paddy3118.blogspot.com]

  >>> t= (1, (1, 2, (1, 2, 3), 3))
  >>> _smash = lambda f: lambda t: sum(map(f, t), ()) if type(t) is tuple else (t,)
  >>> Y = lambda f: (lambda x: x(x))(lambda y: f(lambda z: y(y)(z)))
  >>> # From two non recursive functions:
  >>> smash = Y(_smash)
  >>> smash(t)
  (1, 1, 2, 1, 2, 3, 3)
  >>> 
  

  
  

  Remember: Don't do this at home folks :-)

  - Paddy.

• 
  apoirier

  March 13th, 2009, 8:34 a.m.

  One liner variation, working with any iterable:

  flatten = lambda t: sum(map(flatten, t), ()) if hasattr(t, ‘__iter__’) else (t,)

• 
  Eno

  March 19th, 2009, 6:23 p.m.

  from itertools import chain
  
  flatten = lambda x :chain(*(flatten(v) if type(v) is tuple else (v,) for v in x))
  
  t = (1, (1, 2, (1, 2, 3), 3))
  print list(flatten(t))
  

  
  

  I recommend a visit to http://www.challenge-you.com [challenge-you.com] if you enjoy those kind of challenges.