I need to develop a simple list manipulation. Although it seems easier to
do it in matrix form, but I need it in list form.

I have a matrix

x <- matrix(c(12.1, 3.44, 0.1, 3, 12, 33.1, 1.1, 23), nrow=2)

for list form example, the conversion is

x.list <- lapply(seq_len(nrow(x)), function(i) x[i,])


### list version
calcnorm=function(a, b){
    diff <- mapply("-", a, b)
    diff2 <- mapply("*", diff, diff)
    sqrt.diff <-sqrt(sum(diff2))
    return(sqrt.diff)
}
calcnorm2=function(a,X){
    lapply(X, calcnorm, a)
}
lapply(x.list, calcnorm, x.list)

[[1]]
[[1]][[1]]
[1] 0

[[1]][[2]]
[1] 31.75257


[[2]]
[[2]][[1]]
[1] 31.75257

[[2]][[2]]
[1] 0


### matrix version
calcnorm.const=function(a,b){
    return(sqrt((a-b)%*%(a-b)))
}
calcnorm2.const=function(a,data){
    apply(data,1,calcnorm.const,a)
}
apply(x,1,calcnorm2.const,x)

         [,1]     [,2]
[1,]  0.00000 31.75257
[2,] 31.75257  0.00000

Ideally, for later purposes, the list form of the output should be
something like

[[1]]
[1,]  0 31.75257
[[2]]
[2,] 31.75257  0

I am getting confused here. Could anyone help me out for the right output
FORM?

ishida

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