Dear all I want to find a distance between two points in three dimensional space and an angle between two vectors from [0,0,0] to specified points. I searched archives and found some solution using dist but I am not sure how to use it if I have several sets of such points.
Here is some example #Four points y <- c(1,0,0) z <- c(1,1,0) x <- 2*z v <- 2*x # two sets mata<-rbind(y,x) > mata [,1] [,2] [,3] y 1 0 0 x 2 2 0 matb<-rbind(z,v) > matb [,1] [,2] [,3] z 1 1 0 v 4 4 0 # I want a distances and angles > dist(rbind(y,z)) [1] 1 > dist(rbind(y/sum(y),z/sum(z))) [1] 0.7071068 > dist(rbind(x,v)) [1] 2.828427 > dist(rbind(x/sum(x),v/sum(v))) [1] 0 # they are actually here but they are a little bit hidden > dist(rbind(mata,matb)) y x z x 2.236068 z 1.000000 1.414214 v 5.000000 2.828427 4.242641 > dist(rbind(mata/rowSums(mata),matb/rowSums(matb))) y x z x 0.7071068 z 0.7071068 0 v 0.7071068 0 0 Before I start programming a for loop (something like that) for (i in 1:length(mata)) result<-dist(rbind(mata[i,],matb[i,])) I would like to ask some more experienced if there is a way how to get a vector of distances and angles directly? Something like some.experienced.use.of.dist(mata,matb) resulting in matrix or dataframe or 2 vectors or whatever distance angle 1 1, .7071068 2 2.828427, 0 will be greatly appreciated. Thanks Petr Pikal Petr Pikal [EMAIL PROTECTED] ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help