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Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement?

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From srinivas devaki <mr.eightnoteight@gmail.com>
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Subject Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement?
Date Thu, 12 May 2016 13:53:55 +0530
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On May 9, 2016 5:31 AM, "Tim Chase" <python.list@tim.thechases.com> wrote:
>
> then that's a bad code-smell (you get quadratic behavior as the
> strings are constantly resized), usually better replaced with
>

I just want to point out that in Python s += str in loop is not giving
quadratic behavior. I don't know why but it runs fast. I'm very much
interested to know why it is so?

In [3]: %%timeit
   ...: s = ''
   ...: for x in xrange(10**6):
   ...:     s += str(x)
   ...:
1 loop, best of 3: 383 ms per loop

In [4]: %%timeit
s = ''
for x in xrange(10**6):
    s = s + str(x)
   ...:
1 loop, best of 3: 383 ms per loop

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Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? DFS <nospam@dfs.com> - 2016-05-08 19:10 -0400
  Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Tim Chase <python.list@tim.thechases.com> - 2016-05-08 18:37 -0500
  Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Joel Goldstick <joel.goldstick@gmail.com> - 2016-05-08 20:02 -0400
  String concatenation (was: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement?) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-05-09 02:44 +0200
    Re: String concatenation (was: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement?) Chris Angelico <rosuav@gmail.com> - 2016-05-09 12:16 +1000
      Re: String concatenation Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-05-09 23:21 +0200
        Re: String concatenation Steven D'Aprano <steve@pearwood.info> - 2016-05-10 12:32 +1000
          Re: String concatenation Chris Angelico <rosuav@gmail.com> - 2016-05-10 12:42 +1000
            Re: String concatenation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-05-12 17:43 +1000
        Re: String concatenation Rustom Mody <rustompmody@gmail.com> - 2016-05-09 20:45 -0700
          Re: String concatenation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-05-10 16:46 +1000
            Re: String concatenation Paul Rubin <no.email@nospam.invalid> - 2016-05-10 00:13 -0700
              Re: String concatenation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-05-10 17:54 +1000
                Re: String concatenation David Palao <dpalao.python@gmail.com> - 2016-05-10 10:15 +0200
                Re: String concatenation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-05-12 17:27 +1000
    Re: String concatenation (was: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement?) srinivas devaki <mr.eightnoteight@gmail.com> - 2016-05-09 09:01 +0530
    Re: String concatenation (was: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement?) srinivas devaki <mr.eightnoteight@gmail.com> - 2016-05-09 09:13 +0530
    Re: String concatenation (was: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement?) Michael Selik <michael.selik@gmail.com> - 2016-05-09 18:29 +0000
    Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? DFS <nospam@dfs.com> - 2016-05-10 19:53 -0400
      Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-05-11 02:16 +0200
        Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? DFS <nospam@dfs.com> - 2016-05-10 20:33 -0400
        Moderation [was Re: ...What's wrong with this concatenation statement?] Steven D'Aprano <steve@pearwood.info> - 2016-05-11 11:17 +1000
        Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Chris Angelico <rosuav@gmail.com> - 2016-05-11 11:43 +1000
          Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-05-11 21:12 +0200
        Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Ned Batchelder <ned@nedbatchelder.com> - 2016-05-11 12:39 -0700
          Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Chris Angelico <rosuav@gmail.com> - 2016-05-12 09:07 +1000
          Re: % formatting vs .format() (was: What's wrong with this concatenation statement?) Tim Chase <python.list@tim.thechases.com> - 2016-05-11 18:31 -0500
    Re: String concatenation (was: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement?) sohcahtoa82@gmail.com - 2016-05-10 17:38 -0700
      Re: String concatenation Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-05-11 21:14 +0200
        Re: String concatenation sohcahtoa82@gmail.com - 2016-05-11 14:30 -0700
          Re: String concatenation Ned Batchelder <ned@nedbatchelder.com> - 2016-05-11 14:50 -0700
          Re: String concatenation DFS <nospam@dfs.com> - 2016-05-11 18:25 -0400
  Re: What's wrong with this concatenation statement? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-05-09 17:53 +1000
    Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? DFS <nospam@dfs.com> - 2016-05-10 12:16 -0400
      Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Rustom Mody <rustompmody@gmail.com> - 2016-05-10 09:41 -0700
      Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Stephen Hansen <me+python@ixokai.io> - 2016-05-10 09:42 -0700
        Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? DFS <nospam@dfs.com> - 2016-05-10 18:37 -0400
      Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Steven D'Aprano <steve@pearwood.info> - 2016-05-11 02:44 +1000
      Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Ian Kelly <ian.g.kelly@gmail.com> - 2016-05-10 12:15 -0600
        Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? DFS <nospam@dfs.com> - 2016-05-10 17:21 -0400
          Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Chris Angelico <rosuav@gmail.com> - 2016-05-11 07:27 +1000
            Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? DFS <nospam@dfs.com> - 2016-05-10 19:40 -0400
              Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Paul Rubin <no.email@nospam.invalid> - 2016-05-10 19:14 -0700
              Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? alister <alister.ware@ntlworld.com> - 2016-05-12 09:12 +0000
                Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Chris Angelico <rosuav@gmail.com> - 2016-05-12 19:23 +1000
                Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? DFS <nospam@dfs.com> - 2016-05-12 08:24 -0400
                Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Michael Torrie <torriem@gmail.com> - 2016-05-12 08:39 -0600
                Why online forums have bad behaviour (was: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement?) Ben Finney <ben+python@benfinney.id.au> - 2016-05-13 05:36 +1000
                Re: Why online forums have bad behaviour (was: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement?) Jason Friedman <jsf80238@gmail.com> - 2016-05-12 21:05 -0600
          Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Ethan Furman <ethan@stoneleaf.us> - 2016-05-10 15:12 -0700
            Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? DFS <nospam@dfs.com> - 2016-05-10 19:29 -0400
              Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-05-12 13:39 +0000
                Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Chris Angelico <rosuav@gmail.com> - 2016-05-12 23:50 +1000
          Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Ethan Furman <ethan@stoneleaf.us> - 2016-05-10 16:16 -0700
            Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? DFS <nospam@dfs.com> - 2016-05-10 19:41 -0400
  Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? srinivas devaki <mr.eightnoteight@gmail.com> - 2016-05-12 13:53 +0530
    Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Ned Batchelder <ned@nedbatchelder.com> - 2016-05-12 02:36 -0700
      Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Steven D'Aprano <steve@pearwood.info> - 2016-05-13 01:06 +1000
  Re: Steve D'Aprano, you're the "master". What's wrong with this concatenation statement? Chris Angelico <rosuav@gmail.com> - 2016-05-12 18:40 +1000

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