Re: Pattern Matching in Lists

*To*: mathgroup at smc.vnet.net*Subject*: [mg35561] Re: Pattern Matching in Lists*From*: Tom Burton <tomburton at earthlink.net>*Date*: Fri, 19 Jul 2002 06:08:07 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hello, Here is a straightforward way, but in two steps. First, reform the patterns into list elements: w2 = w //. {a___, 1, 0, b___} :> {a, p, b} Where "p" is any symbol that does not appear in w. Then use Count in the usual way: Count[w2, p] Tom Burton On 7/18/02 12:18 AM, in article ah5qce$59o$1 at smc.vnet.net, "Anthony Mendes" <amendes at zeno.ucsd.edu> 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! >