day9: better ascii map for debug

day9/day9.jl

@@ -1,6 +1,7 @@
 #!/usr/bin/env julia
 
 using Test
+using Images
 
 struct Move
   direction :: Char
@@ -70,16 +71,45 @@ function get_visited(moves; nknots::Int=2)
   return visited
 end
 
-function visited_map(visited)
+function int_map(visited)
   (min_x, max_x) = extrema([t[1] for t in visited])
   (min_y, max_y) = extrema([t[2] for t in visited])
   nrows = max_y - min_y + 1
   ncols = max_x - min_x + 1
-  vmap = zeros(Int, nrows, ncols)
+  imap = zeros(Int, nrows, ncols)
   for (x, y) in visited
-    vmap[nrows - (y - min_y), (x - min_x + 1)] = 1
+    imap[nrows - (y - min_y), (x - min_x + 1)] = 1
   end
-  return vmap
+  imap[nrows + min_y, 1 - min_x] = -1
+  return imap
+end
+
+function ascii_map(visited)
+  map_char(n) = (n == -1 ? 's'
+                 : (n == 1 ? "#"[1] : '.'))
+  srows = mapreduce(map_char, *, int_map(visited), dims=2; init="")
+  return join(srows, "\n")
+end
+
+function scale_pixels(img, scale::Int)
+  (nrows, ncols) = size(img)
+  new_img = Matrix{RGB}(undef, nrows * scale, ncols * scale)
+  for i in 1:nrows
+    for j in 1:ncols
+      i2 = (i - 1) * scale + 1
+      j2 = (j - 1) * scale + 1
+      new_img[i2:i2+scale-1, j2:j2+scale-1] .= img[i, j]
+    end
+  end
+  return new_img
+end
+
+function image_map(visited; scale::Int=10)
+  imap = int_map(visited)
+  map_color(n) = (n == -1 ? RGB(0, 0.8, 0)
+                  : (n == 1 ? RGB(0.2, 0.2, 0.0) : RGB(0, 0, 0)))
+  cmap = map(map_color, int_map(visited))
+  return scale_pixels(cmap, scale)
 end
 
 function test()
@@ -104,15 +134,14 @@ function main()
     visited = get_visited(moves)
     println("visited: ", visited)
     println("count  : ", length(visited))
-    display(visited_map(visited))
-    println()
+    println(ascii_map(visited))
+    save("visited.png", image_map(visited))
 
     visited10 = get_visited(moves, nknots=10)
     println("visited10: ", visited10)
     println("count10  : ", length(visited10))
-    display(visited_map(visited10))
-    println()
-
+    println(ascii_map(visited10))
+    save("visited10.png", image_map(visited10))
   end
 end