Re: number of switches

*To*: mathgroup at smc.vnet.net*Subject*: [mg47513] Re: [mg47479] number of switches*From*: János <janos.lobb at yale.edu>*Date*: Thu, 15 Apr 2004 03:39:15 -0400 (EDT)*References*: <200404141116.HAA27212@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On Apr 14, 2004, at 7:16 AM, fake 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)? > > My newbie approaches: lst = {1, 0, 1, 0, 1} Length[Cases[ Partition[lst, 2, 1], {1, 0}]] + Length[Cases[Partition[ lst, 2, 1], {0, 1}]] 4 or Length[Partition[lst, 2, 1]] - Length[Position[Partition[lst, 2, 1], {a_, a_} ]] 4 I am sure there is an easier way without a Plus or Minus, but I am not good at pattern matching. János ------------------------------------------------- clear perl code is better than unclear awk code; but NOTHING comes close to unclear perl code http://www.faqs.org/faqs/computer-lang/awk/faq/

**References**:**number of switches***From:*"fake" <fake@fake.it>