Simple way to impute missing values in matrix

impute.matrix.R

impute.matrix <- function (matrix) {
	missing <- which(is.na(matrix) | !is.finite(matrix), arr.ind=TRUE)
	if (length(missing)!=0){
		for (j in 1:nrow(missing)){
				mean <- mean(matrix[missing[j,1],][is.finite(matrix[missing[j,1],])], na.rm=TRUE)
				matrix[missing[j,1],missing[j,2]] <- mean
			}
	}
  	matrix
}