R/corw.R

In neuroconductor-devel/ANTsR: ANTs in R: Quantification Tools for Biomedical Images

#' produces a correlation matrix via weighted correlation.
#'
#' Uses weighted regression to compute pairwise correlation matrix on input
#' matrix - by columns.
#'
#'
#' @param mat input matrix
#' @param weights input weights, size of nrow of matrix
#' @return matrix is output
#' @author Avants BB
#' @examples
#'
#' mat <- matrix( rnorm(100), nrow=10 )
#' wcmat<-corw( mat , weights = abs( nrorm( nrow(mat) ) ) )
#'
#' @export corw
corw <- function(mat, weights) {
  if (missing(mat) | missing(weights)) {
    print(args(corw))
    return(1)
  }
  cormat <- matrix(rep(NA, ncol(mat) * ncol(mat)), ncol = ncol(mat))
  for (x in 1:ncol(mat)) {
    for (y in 1:ncol(mat)) {
      if ( x != y )
      {
      cormat[x, y] <- sqrt(summary(lm(mat[, x] ~ mat[, y]), weights = weights/sum(weights))$r.squared)
      }
    }
  }
  return(cormat)
}