Re: [functional approach should give] an even faster way to normalize

*To*: mathgroup at smc.vnet.net*Subject*: [mg85666] Re: [functional approach should give] an even faster way to normalize*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Tue, 19 Feb 2008 01:48:48 -0500 (EST)*References*: <fp9945$199$1@smc.vnet.net>

Hi, what is with Map[ If[Min[#]>=0 && Max[#]<=1,#,{0,0,0}] &, sum, {2} ] it is still more compact. Regards Jens congruentialuminaire at yahoo.com wrote: > Hello UG: > > I have a 512x512 array of 3-tuples. I want to make any tuple with a > value outside of 0 <--> 1, become {0.,0.,0.}. > > The first version has this loop: > > For[i = 1, i <= graphSize, i++, > For[j = 1, j <= graphSize, j++, > If[((sum[[i, j, 1]] < 0) || (sum[[i, j, 1]] > 1) || > (sum[[i, j, 2]] < 0) || (sum[[i, j, 2]] > 1) || > (sum[[i, j, 3]] < 0) || (sum[[i, j, 3]] > 1)), > sum[[i, j]] = {0., 0., 0.} > ] > ] > ]; > > After scratching my head for a while I came up with this (equivalent) > Map statement. > > sum = Map[ > If[#[[1]] < 0 || #[[1]] > 1 || #[[2]] < 0 || #[[2]] > 1 || #[[3]] < > 0 || #[[3]] > 1, {0., 0., 0.}, #] &, sum, {2}]; > > It is faster but only by about 15%. > > It is unreasonable to believe some other construction can accomplish > this with a bigger payoff? > > Thanks in advance. > > Regards..Roger W. >