add: plot_matrix

tensorPredictors/R/plot_matrix.R

@@ -0,0 +1,27 @@
+#' Plots a matrix an image
+#'
+#' @param A a matrix to be plotted
+#' @param main overall title for the plot
+#' @param interpolate a logical vector (or scalar) indicating whether to apply
+#'  linear interpolation to the image when drawing.
+#' @param ... further arguments passed to \code{\link{rasterImage}}
+#'
+#' @export
+plot.matrix <- function(A, main = NULL, interpolate = FALSE, ...) {
+
+    # Scale values of `A` to [0, 1] with min mapped to 1 and max to 0.
+    A <- (max(A) - A) / diff(range(A))
+
+    # plot raster image
+    plot(c(0, ncol(A)), c(0, nrow(A)), type = "n", bty = "n", col = "red",
+        xlab = "", ylab = "", xaxt = "n", yaxt = "n", main = main)
+
+    # Add X-axis giving index
+    ind <- seq(1, ncol(A), by = 1)
+    axis(1, at = ind - 0.5, labels = ind, lwd = 0, lwd.ticks = 1)
+    # Add Y-axis
+    ind <- seq(1, nrow(A))
+    axis(2, at = ind - 0.5, labels = rev(ind), lwd = 0, lwd.ticks = 1, las = 1)
+
+    rasterImage(A, 0, 0, ncol(A), nrow(A), interpolate = interpolate, ...)
+}