parray: Representation of and operations on multidimensional tables

In gRbase: A package for graphical modelling in R

Description

General representation of multidimensional tables (by parray objects).

Usage

parray(varNames, levels, values = 1, normalize = "none", smooth = 0)
as.parray(values, normalize="none", smooth=0)
data2parray(data, varNames=NULL, normalize="none", smooth=0)

Arguments

varNames	Names of variables defining table; can be a right hand sided formula.
levels	Either 1) a vector with number of levels of the factors in varNames or 2) a list with specification of the levels of the factors in varNames. See 'examples' below.
values	Values to go into the parray
normalize	Either "none", "first" or "all". Should result be normalized, see 'Details' below.
smooth	Should values be smoothed, see 'Details' below.
data	A dataframe, a table, an xtabs (a cross classified contingency table) a matrix (with dimnames) or a vector (with dimnames).

Details

A parray 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 all other variables than the first, 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.parray can be used for coercing an array or an xtabs to a parray object.

Value

An object of class parray.

Author(s)

S<f8>ren H<f8>jsgaard, [e-mail]

See Also

tableOp, tableMargin

Examples

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

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

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


## Create 1-dimensional vector with dim and dimnames
x1 <- 1:5
as.parray(x1)
x2 <- parray("x", levels=length(x1), values=x1)
dim(x2)
dimnames(x2)

## Matrix
x1 <- matrix(1:6, nrow=2)
as.parray(x1)
parray(~a:b, levels=dim(x1), values=x1)

## Extract parrays from data
## 1) a dataframe
data(cad1) 
data2parray(cad1, ~Sex:AngPec:AMI)
data2parray(cad1, c("Sex","AngPec","AMI"))
data2parray(cad1, c(1,2,3))
## 2) a table
data2parray(UCBAdmissions,c(1,2), normalize="first")

gRbase documentation built on May 2, 2019, 4:51 p.m.