gdist and gower distance
Dear All, I would like to ask clarifications on the gower distnce matrix calculated by the function gdistin the library mvpart. Here is a dummy example:
library(mvpart)
Loading required package: survival Loading required package: splines mvpart package loaded: extends rpart to include multivariate and distance-based partitioning
x=matrix(1:6, byrow=T, ncol=2) x
[,1] [,2] [1,] 1 2 [2,] 3 4 [3,] 5 6
gdist(x, method="euclid")
1 2 2 2.828427 3 5.656854 2.828427 ########################## doing the calculations by hand according to the formula in gdist help page I get the same results. The formula given is: 'euclidean' d[jk] = sqrt(sum (x[ij]-x[ik])^2) #################################
sqrt(8)
[1] 2.828427
gdist(x, method="gower")
1 2 2 0.7071068 3 1.4142136 0.7071068 ####################################### doing the calculations by hand according to the formula in gdist help page cannot reproduce the same results. The formula given is: 'gower' d[jk] = sum (abs(x[ij]-x[ik])/(max(i)-min(i)) ########################################## Could anybody please shed some light? Regards, Alessio Boattini