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Re: Sorting strings

  • To: mathgroup at smc.vnet.net
  • Subject: [mg123147] Re: Sorting strings
  • From: Ray Koopman <koopman at sfu.ca>
  • Date: Thu, 24 Nov 2011 06:59:16 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <jainvm$eop$1@smc.vnet.net>

On Nov 23, 4:12 am, Themis Matsoukas <tmatsou... at me.com> wrote:
> Sorting this list of strings
>
> {"a1", "a2", "a20", "a12"} // Sort
>
> I get
>
> {"a1", "a12", "a2", "a20"}
>
> but I would like the numerals to be sorted as numbers, i.e., as
>
> {"a1", "a2", "a12",  "a20"}
>
> Is this possible or do I have to rename "a1" into "a01" etc?
>
> Thanks
>
> Themis

Drop the "a", convert to numeric, sort, convert to ascii,
and re-attach the "a".

In[1]:=
"a"<>ToString@#&/@Sort[ToExpression@StringDrop[#,1]&/@
{"a1", "a2", "a20", "a12"}] //InputForm

Out[1]//InputForm=
{"a1", "a2", "a12", "a20"}



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