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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