# R/ind2x2.R In robCompositions: Compositional Data Analysis

#### Documented in ind2x2

#' Independence 2x2 compositional table
#'
#' Estimates the expected frequencies from an 2x2 table under the
#' null hypotheses of independence.
#'
#' @param x a 2x2 table
#' @param margin if multidimensional table (larger than 2-dimensional),
#' then the margin determines on which dimension the independene tables should be estimated.
#' @param pTabMethod \sQuote{classical} that is function \code{prop.table()} from package base or method \dQuote{half} that add 1/2 to each cell
#' to avoid zero problems.
#' @author Kamila Facevicova, Matthias Templ
#' @return The independence table(s) with either relative or absolute frequencies.
#' @references
#' Facevicova, K., Hron, K., Todorov, V., Guo, D., Templ, M. (2014).
#' Logratio approach to statistical analysis of 2x2 compositional tables.
#' \emph{Journal of Applied Statistics}, 41 (5), 944--958.
#' @export
#' @examples
#' data(employment)
#' ind2x2(employment)
ind2x2 <- function(x, margin=3, pTabMethod = c("dirichlet", "half", "classical")){
## Matthias Templ, TU WIEN, 17.01.2013
pTabMethod <- match.arg(pTabMethod)
ind2tab <- function(x){
## Matthias Templ, TU WIEN, 17.01.2013
if(!all.equal(dim(x), c(2,2))) stop("ind2.table is for 2x2 tables.")
xind <- x
xind[1,1] <- x[1,1]*(x[2,1]*x[1,2])^(1/2)
xind[2,1] <- x[2,1]*(x[1,1]*x[2,2])^(1/2)
xind[1,2] <- x[1,2]*(x[1,1]*x[2,2])^(1/2)
xind[2,2] <- x[2,2]*(x[2,1]*x[1,2])^(1/2)
pTab(xind, method = pTabMethod)
}
dn <- dimnames(x)
if(length(dim(x)) == 2){
res <- ind2tab(x)
} else {
res <- apply(x, margin, ind2tab)
res <- array(res, dim=c(2,2,ncol(res)))
}
dimnames(res) <- dn
class(res) <- "ind2x2"
res
}


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robCompositions documentation built on Aug. 25, 2023, 5:13 p.m.