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MathGroup Archive 2004

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Re: number of switches

  • To: mathgroup at smc.vnet.net
  • Subject: [mg47548] Re: number of switches
  • From: Paul Abbott <paul at physics.uwa.edu.au>
  • Date: Thu, 15 Apr 2004 05:02:14 -0400 (EDT)
  • Organization: The University of Western Australia
  • References: <c5j6vd$qqo$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

In article <c5j6vd$qqo$1 at smc.vnet.net>, "fake" <fake at fake.it> wrote:

> Consider the lists {1,1,0,1} and {1,1,0,0},{1,0,1,0,1}.
> The first sequence (1101) switches 2 times (#2digit~#3digit,
> #3digit~#4digit}, the second (1100) 1 time, the third 10101 4 times.
> 
> I have the following problem.
> Consider a list of binary digits. Which is the easiest way to count the
> number of switches of the list (using Mathematica commands)?

Use Split:

  Switches[l_List] := Length[Split[l]] - 1

This works with arbitrary lists of numbers or symbols.

Cheers,
Paul

-- 
Paul Abbott                                   Phone: +61 8 9380 2734
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