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MathGroup Archive 2002

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Re: Pattern Matching in Lists

  • To: mathgroup at smc.vnet.net
  • Subject: [mg35570] Re: [mg35547] Pattern Matching in Lists
  • From: "Julio Vera" <jvera at adinet.com.uy>
  • Date: Fri, 19 Jul 2002 06:08:42 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Anthony,

Here´s how I´d do it.

Load a package that contains the function Frequencies
In[1]:=
<<Statistics`DataManipulation`

Then apply the function Frequencies to a Partition of w that contains pairs
of it´s elements, each of them starting with each of the elements of w
(except the last one, since it doesn´t have one to follow it).

In[2]:=
Frequencies[Partition[w,2,1]]

Out[2]=
{{3,{0,0}},{4,{0,1}},{4,{1,0}},{2,{1,1}}}

The third element of this list shows w contains 4 elements 1 that are
followed by an element 0 .

Julio


>
> ----- Mensaje original -----
> De: "Anthony Mendes" <amendes at zeno.ucsd.edu>
> Para: <mathgroup at smc.vnet.net>
> Enviado: Jueves 18 de Julio de 2002 04:06 AM
> Asunto: [mg35547] Pattern Matching in Lists
>
>
> > Hello,
> >
> > Suppose w={1,1,1,0,0,1,0,1,0,0,1,0,0}.
> >
> > How can I count the number of occurrences of a 1 in w immediately
> > followed by a 0 in w?
> >
> > I have tried every incarnation of Count[] I can think of; for example,
> >
> > Count[w,{___,1,0,___}]
> >
> > does not seem to work.  In general, how can I count the number of
> > occurrences of a 1 followed by a 0 in a list of 1's and 0's?  Thank you!
> >
> >
> > --
> > Tony
> > _____________________
> > amendes at math.ucsd.edu
> >
> >
>



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