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Re: Sorting strings


On Wed, 23 Nov 2011 12:12:38 -0000, Themis Matsoukas <tmatsoukas 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
>

You could try:

lst = {"a1", "a12", "a2", "a20"};

nums =
  ToExpression@StringTrim[{"a1", "a12", "a2", "a20"}, LetterCharacter]

{1, 12, 2, 20}

Part[lst, Ordering[nums]]

{"a1", "a2", "a12", "a20"}



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