[R] gdist and gower distance

[Alessio Boattini]

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