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Groups > comp.lang.python > #66831

Re: Remove comma from tuples in python.

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On 2014-02-21 09:29, Alister wrote:
> >    >>> seriesxlist1 = ((0.0,), (0.01,), (0.02,))
> >    >>> x2 = [x*x for (x,) in seriesxlist1]  
> > 
> > I tend to omit those parentheses and use just the comma:
> >   
> >    >>> x2 = [x*x for x, in seriesxlist1]  
> 
> I had not though of using unpacking in this way & would have written
> 
> x2= [x[0]**2 for x in serisexlist1]
> 
> I am not sure which is easier to read in this instance (single
> element tupple) but unpacking would definitely be the way to go if
> the tupple had multiple values.

With the single-value tuple, I tend to find the parens make it more
readable, so I'd go with

  [x*x for (x,) in lst]

whereas if they were multi-value tuples, I tend to omit the parens:

  [x*y for x,y in lst]

though, tangentially, Python throws a SyntaxError if you try and pass
a generator to a function without extra outer parens because it
makes parsing them ambiguous otherwise:

  >>>  x = sum(a+b for a, b in lst, 10)
  File "<stdin>", line 1
SyntaxError: Generator expression must be parenthesized if not sole
argument
  >>> x = sum((a+b) for a,b in lst), 10)
  [no error]

-tkc

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Remove comma from tuples in python. Jaydeep Patil <patil.jay2009@gmail.com> - 2014-02-20 22:49 -0800
  Re: Remove comma from tuples in python. Mircescu Andrei <mircescu.andrei@gmail.com> - 2014-02-20 23:02 -0800
    Re: Remove comma from tuples in python. Stephane Wirtel <stephane@wirtel.be> - 2014-02-21 08:11 +0100
    Re: Remove comma from tuples in python. Bernd Nawothnig <Bernd.Nawothnig@t-online.de> - 2014-02-21 08:20 +0100
  Re: Remove comma from tuples in python. Gary Herron <gary.herron@islandtraining.com> - 2014-02-21 00:27 -0800
    Re: Remove comma from tuples in python. Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2014-02-21 11:13 +0200
      Re: Remove comma from tuples in python. Alister <alister.ware@ntlworld.com> - 2014-02-21 09:29 +0000
        Re: Remove comma from tuples in python. Tim Chase <python.list@tim.thechases.com> - 2014-02-21 08:00 -0600
        Re: Remove comma from tuples in python. Peter Otten <__peter__@web.de> - 2014-02-21 15:14 +0100
          Re: Remove comma from tuples in python. Roy Smith <roy@panix.com> - 2014-02-21 09:32 -0500
            Re: Remove comma from tuples in python. Travis Griggs <travisgriggs@gmail.com> - 2014-02-21 09:48 -0800
            Re: Remove comma from tuples in python. Tim Chase <python.list@tim.thechases.com> - 2014-02-21 12:07 -0600
            Re: Remove comma from tuples in python. Cameron Simpson <cs@zip.com.au> - 2014-02-24 12:19 +1100
  Re: Remove comma from tuples in python. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-02-21 14:02 +0000

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