Merge matrix rows with same name

merge_rows.R

merge_rows <- function(x, method=mean, na.rm=FALSE) 
{
  x <- as.matrix(x[!is.na(rownames(x)), ])
  r <- unique(rownames(x))
  m <- length(r)
  if (dim(x)[1] != m) {
    y <- matrix(nrow=m, ncol=dim(x)[2])
    rownames(y) <- r
    colnames(y) <- colnames(x)
    for (i in 1:m) {
      n <- sum(rownames(x) == r[i])
      if (n > 1) {
        s <- as.matrix(x[rownames(x) == r[i], ])
        y[i, ] <- apply(s, 2, method, na.rm)
      } 
      else {
        y[i, ] <- x[r[i], ]
      }
    }
  }
  else {
    y <- x
  }
  y
}