Re: Finding lengths of identical sequences in lists

• To: mathgroup at smc.vnet.net
• Subject: [mg20270] Re: [mg20240] Finding lengths of identical sequences in lists
• From: Maris Tonso <maris at tpu.ee>
• Date: Sun, 10 Oct 1999 01:27:28 -0400
• References: <199910082230.SAA04776@smc.vnet.net.>
• Sender: owner-wri-mathgroup at wolfram.com

```Hope this helps:

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

Maris Tonso

Joel Cannon wrote:

> 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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