Re: number of switches

*To*: mathgroup at smc.vnet.net*Subject*: [mg47507] Re: [mg47479] number of switches*From*: Sseziwa Mukasa <mukasa at jeol.com>*Date*: Thu, 15 Apr 2004 03:39:10 -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)? > I don't know what you consider easy. If you're list is not too long you can do it recursively countswitches[{x_}]:=0 countswitches[l_List]:=If[l[[1]]! =l[[2]],1+countswitches[Rest[l]],countswitches[Rest[l]]] If you're worried about recursing too deeply do it iteratively countswitches[l_List]:=Module[{acc=0},Do[If[l[[i]]! =l[[i+1]],acc++],{i,Length[l]-1}];acc] Regards, Ssezi

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