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MathGroup Archive 1999

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Re: Finding lengths of identical sequences in lists

  • To: mathgroup at smc.vnet.net
  • Subject: [mg20259] Re: Finding lengths of identical sequences in lists
  • From: "Allan Hayes" <hay at haystack.demon.co.uk>
  • Date: Sun, 10 Oct 1999 00:04:09 -0400
  • References: <7tkvi6$3v9@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Joel,

Length /@ Split[{3, 2, 2, 3, 3, 3, 1} ]

    {1, 2, 3, 1}

Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565


Joel Cannon <jcannon at jcannon.washjeff.edu> wrote in message
news:7tkvi6$3v9 at smc.vnet.net...
> I am looking for a more elegant solution to the following. I have a
> list (a list of positions at consecutive times).  I wish to create a
> new list of the length of each sequence of consecutive identical
> members (including those of length 1).
>
> For example, for the list {3,2,2,3,3,3,1} I would create the list
> {1,2,3,1} because the first 3 appears once, followed by two 2's,
> etc. The lists I was working with contained a list of numbers
> (e.g. {{x1,y1},{x2,y2},...} rather than simple numbers. I accomplished
> this using a while loop, but I suspect there are better ways to do
> this using pattern matching or other approaches.
>
> Thanks much.
>
>
> --------------------------------------------------------------------------
----
> Joel W. Cannon                   |   (724)223-6146
> Dept. of Physics                 |
> Washington and Jefferson College |
> Washington, PA 15301             |
>
>
>
>
>



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