Add a highlight matrix

NAMESPACE

@@ -2,6 +2,7 @@
 
 export(draw_matrix)
 export(gdraw_matrix)
+export(highlight_matrix)
 importFrom(graphics,mtext)
 importFrom(graphics,par)
 importFrom(graphics,plot.new)

R/highlight.R

@@ -0,0 +1,59 @@
+#' Highlight a matrix
+#' 
+#' Generate a matrix with active areas.
+#' 
+#' @param x       A matrix.
+#' @param rows    An interger vector with valid row index locations.
+#' @param columns An integer vector containing valid column indexlocations.
+#' @param points  An m by 2 matrix with points listed in x, y format.
+#'
+#' @return 
+#' A logical matrix with the required rows and/or columns or points set to
+#' `TRUE`. All other values are given as `FALSE`.
+#'
+#' @export
+#' @examples
+#' 
+#' x = matrix(1:12, nrow = 4)
+#' 
+#' # Highlight entries only in the 1st and 3rd rows.
+#' highlight_matrix(x, rows = c(1, 3))
+#' 
+#' # Highlight entries only in the first two rows:
+#' highlight_matrix(x, rows = 1:2)
+#' 
+#' # Highlight entries in the last row
+#' highlight_matrix(x, rows = nrow(x))
+#' 
+#' # Highlight entries in the first column
+#' highlight_matrix(x, columns = 1)
+#' 
+#' # Highlight entries in the first column or first row.
+#' highlight_matrix(x, rows = 1, columns = 1)
+highlight_matrix <- function(x, rows = NULL, columns = NULL, points = NULL) {
+
+  # Create a logical matrix with the same dimensions as 'x'
+  logical_matrix <- matrix(FALSE, nrow = nrow(x), ncol = ncol(x))
+
+  # Nothing to mark.
+  if (is.null(rows) && is.null(columns) && is.null(points)) {
+    return(logical_matrix)
+  }
+
+  if(!is.null(points)){
+    stopifnot("points must contain only two columns." = ncol(points) == 2)
+    logical_matrix[points] <- TRUE
+  }
+
+  # Enable rows
+  if(!is.null(rows)){
+    logical_matrix[rows, ] <- TRUE
+  }
+
+  # Enable columns
+  if(!is.null(columns)){
+    logical_matrix[, columns] <- TRUE
+  }
+
+  logical_matrix
+}