Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #29496

Re: sum works in sequences (Python 3)

Show all headers | View raw

On 2012-09-19, Franck Ditter <franck@ditter.org> wrote:
> Hello,
> I wonder why sum does not work on the string sequence in Python 3 :
>
>>>> sum((8,5,9,3))
> 25
>>>> sum([5,8,3,9,2])
> 27
>>>> sum('rtarze')
> TypeError: unsupported operand type(s) for +: 'int' and 'str'
>
> I naively thought that sum('abc') would expand to 'a'+'b'+'c'
> And the error message is somewhat cryptic...

You got that error message because the default value for the
second 'start' argument is 0. The function tried to add 'r' to 0.
That said:

>>> sum('rtarze', '')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: sum() can't sum strings [use ''.join(seq) instead]

-- 
Neil Cerutti

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

sum works in sequences (Python 3) Franck Ditter <franck@ditter.org> - 2012-09-19 16:41 +0200
  Re: sum works in sequences (Python 3) Joel Goldstick <joel.goldstick@gmail.com> - 2012-09-19 10:57 -0400
  Re: sum works in sequences (Python 3) Neil Cerutti <neilc@norwich.edu> - 2012-09-19 14:57 +0000
  Re: sum works in sequences (Python 3) Ian Kelly <ian.g.kelly@gmail.com> - 2012-09-19 09:03 -0600
    Re: sum works in sequences (Python 3) Neil Cerutti <neilc@norwich.edu> - 2012-09-19 15:06 +0000
      Re: sum works in sequences (Python 3) Ian Kelly <ian.g.kelly@gmail.com> - 2012-09-19 09:24 -0600
      Re: sum works in sequences (Python 3) Steve Howell <showell30@yahoo.com> - 2012-09-19 08:37 -0700
        Re: sum works in sequences (Python 3) Ian Kelly <ian.g.kelly@gmail.com> - 2012-09-19 12:33 -0600
          Re: sum works in sequences (Python 3) Steve Howell <showell30@yahoo.com> - 2012-09-19 11:43 -0700
    Re: sum works in sequences (Python 3) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-09-19 16:14 +0000
  Re: sum works in sequences (Python 3) Alister <alister.ware@ntlworld.com> - 2012-09-19 15:07 +0000
    Re: sum works in sequences (Python 3) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-09-19 16:18 +0000
    Re: sum works in sequences (Python 3) Terry Reedy <tjreedy@udel.edu> - 2012-09-19 14:49 -0400
    Re: sum works in sequences (Python 3) Hans Mulder <hansmu@xs4all.nl> - 2012-09-20 00:25 +0200

csiph-web