gRbase (version 1.3.9)

ptable: Representation of and operations on multidimensional tables

Description

General representation of multidimensional tables (by ptable objects).

Usage

ptable(varNames, levels, values = 1, normalize = c("none", "first", "all"), smooth = 0)
as.ptable  <- function(values, normalize=c("none","first","all"), smooth=0)
tableMarginPrim(t1, margin, normalize=FALSE)

## S3 method for class 'ptable':
varNames(x)
## S3 method for class 'ptable':
nLevels(x)
## S3 method for class 'ptable':
valueLabels(x)

Arguments

varNames

Names of variables defining table

levels

Either vector with number of levels of the factors in varNames or list vith specification of the levels of the factors in varNames. See 'examples' below.

values

Table values

x

Objects of class "ptable"

t1

Objects of class "ptable"

margin

Set of nodes to marginalize onto

normalize

Should result be normalized, see 'Details' below.

smooth

Should values be smoothed, see 'Details' below.

Value

• An object of class ptable.

Details

A ptable object represents a table defined by a set of variables and their levels, together with the values of the table. E.g. f(a,b,c) can be a table with a,b,c representing levels of binary variable If normalize="first" then for each configuration of the parents, "pa", the probabilities are normalized to sum to one. Thus f(a,b,c) becomes a conditional probability table of the form p(a|b,c). If normalize="all" then the sum over all entries of f(a,b,c) is one. If smooth is positive then smooth is added to values before normalization takes place. as.ptable can be used for coercing a an array to a ptable object.

Examples

t1 <- ptable(c("gender","answer"),list(c('male','female'),c('yes','no')), values=1:4)
t1 <- ptable(~gender+answer,list(c('male','female'),c('yes','no')), values=1:4)
t1 <- ptable(~gender+answer,c(2,2), values=1:4)

t2 <- ptable(c("answer","category"), list(c('yes','no'),c(1,2)), values=1:4+10)
t3 <- ptable(c("category","foo"), c(2,2), values=1:4+100)





varNames(t1)
nLevels(t1)
valueLabels(t1)