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Re: Pattern Matching in Lists

  • To: mathgroup at smc.vnet.net
  • Subject: [mg35558] Re: [mg35547] Pattern Matching in Lists
  • From: Adriano Pascoletti <pascolet at dimi.uniud.it>
  • Date: Fri, 19 Jul 2002 06:08:00 -0400 (EDT)
  • References: <200207180706.DAA05322@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

At 3:06 -0400 18-07-2002, Anthony Mendes wrote:
>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!

Anthony,

a possible solution is

In[16]:=
w={1,1,1,0,0,1,0,1,0,0,1,0,0};
Count[Partition[w,2,1],{1,0}]

Out[17]=
4

with matches at

In[18]:=
Position[Partition[w,2,1],{1,0}]

Out[18]=
{{3},{6},{8},{11}}

Adriano Pascoletti


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