api-tabDist function

Marginalize and condition in multidimensional array.

Marginalize and condition in a multidimensional array which is assumed to represent a discrete multivariate distribution.

tabDist(tab, marg = NULL, cond = NULL, normalize = TRUE)

Arguments

• tab: Multidimensional array with dimnames.
• marg: A specification of the desired margin; a character vector, a numeric vector or a right hand sided formula.
• cond: A specification of what is conditioned on. Can take two forms: Form one is a a character vector, a numeric vector or a right hand sided formula. Form two is as a simple slice of the array, which is a list of the form var1=value1, var2=value2 etc.
• normalize: Should the result be normalized to sum to 1.

Returns

A multidimensional array.

Examples

hec <- HairEyeColor

is.named.array( hec )
## We need dimnames, and names on the dimnames

## Marginalize:
tabDist(hec, marg= ~Hair + Eye)
tabDist(hec, marg= ~Hair:Eye)
tabDist(hec, marg= c("Hair", "Eye"))
tabDist(hec, marg= 1:2)

tabDist(hec, marg= ~Hair + Eye, normalize=FALSE)

## Condition
tabDist(hec, cond= ~Sex + Hair)
tabDist(hec, cond= ~Sex:Hair)
tabDist(hec, cond= c("Sex", "Hair"))
tabDist(hec, cond= c(3,1))

tabDist(hec, cond= list(Hair="Black"))
tabDist(hec, cond= list(Hair=1))

## Not run:

## This will fail
tabDist(hec, cond= list(Hair=c("Black", "Brown")))
tabDist(hec, cond= list(Hair=1:2))
## End(Not run)

## But this will do the trick
a <- tabSlice(hec, slice=list(Hair=c("Black", "Brown")))
tabDist(a, cond=~Hair)

## Combined
tabDist(hec, marg=~Hair+Eye, cond=~Sex)
tabDist(hec, marg=~Hair+Eye, cond="Sex")

tabDist(hec, marg=~Hair+Eye, cond=list(Sex="Male"))
tabDist(hec, marg=~Hair+Eye, cond=list(Sex="Male"), normalize=FALSE)

tabDist(hec, cond=list(Sex="Male"))
tabDist(hec, cond=list(Sex="Male"), normalize=FALSE)

Author(s)

Søren Højsgaard, sorenh@math.aau.dk