Data commit

Task/Bitmap-Flood-fill/R/bitmap-flood-fill-1.r

@@ -0,0 +1,23 @@
+library(png)
+img <- readPNG("Unfilledcirc.png")
+M <- img[ , , 1]
+M <- ifelse(M < 0.5, 0, 1)
+image(M, col = c(1, 0))
+
+# https://en.wikipedia.org/wiki/Flood_fill
+floodfill <- function(row, col, tcol, rcol) {
+  if (tcol == rcol) return()
+  if (M[row, col] != tcol) return()
+  M[row, col] <<- rcol
+  floodfill(row - 1, col    , tcol, rcol) # south
+  floodfill(row + 1, col    , tcol, rcol) # north
+  floodfill(row    , col - 1, tcol, rcol) # west
+  floodfill(row    , col + 1, tcol, rcol) # east
+  return("filling completed")
+}
+
+options(expressions = 10000)
+startrow <- 100; startcol <- 100
+floodfill(startrow, startcol, 0, 2)
+
+image(M, col = c(1, 0, 2))

Task/Bitmap-Flood-fill/R/bitmap-flood-fill-2.r

@@ -0,0 +1,37 @@
+library(png)
+img <- readPNG("Unfilledcirc.png")
+M <- img[ , , 1]
+M <- ifelse(M < 0.5, 0, 1)
+M <- rbind(M, 0)
+M <- cbind(M, 0)
+image(M, col = c(1, 0))
+
+# https://en.wikipedia.org/wiki/Flood_fill
+floodfill <- function(row, col, tcol, rcol) {
+  if (tcol == rcol) return()
+  if (M[row, col] != tcol) return()
+  Q <- matrix(c(row, col), 1, 2)
+  while (dim(Q)[1] > 0) {
+    n <- Q[1, , drop = FALSE]
+    west  <- cbind(n[1]    , n[2] - 1)
+    east  <- cbind(n[1]    , n[2] + 1)
+    north <- cbind(n[1] + 1, n[2]    )
+    south <- cbind(n[1] - 1, n[2]    )
+    Q <- Q[-1, , drop = FALSE]
+    if (M[n] == tcol) {
+      M[n] <<- rcol
+      if (M[west] == tcol)  Q <- rbind(Q, west)
+      if (M[east] == tcol)  Q <- rbind(Q, east)
+      if (M[north] == tcol) Q <- rbind(Q, north)
+      if (M[south] == tcol) Q <- rbind(Q, south)
+    }
+  }
+  return("filling completed")
+}
+
+startrow <- 100; startcol <- 100
+floodfill(startrow, startcol, 0, 2)
+startrow <- 50; startcol <- 50
+floodfill(startrow, startcol, 1, 3)
+
+image(M, col = c(1, 0, 2, 3))