Re: Pattern Matching in Lists

*To*: mathgroup at smc.vnet.net*Subject*: [mg35565] Re: Pattern Matching in Lists*From*: Selwyn Hollis <slhollis at earthlink.net>*Date*: Fri, 19 Jul 2002 06:08:26 -0400 (EDT)*References*: <ah5qce$59o$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Here's a simple solution. Say you have a list of 0s and 1s named bits. Compute bits + 2*RotateRight[bits] and drop the first entry. Then count the number of 2s in the result. counter10[bits_]:= Count[Drop[bits+2RotateRight[bits],1],2] -- Selwyn Hollis slhollis at earthlink.net http://www.math.armstrong.edu/faculty/hollis 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! > >