Time for an 2014 update…

Task/Langtons-ant/AutoIt/langtons-ant.autoit

@@ -0,0 +1,76 @@
+Global $iCountMax = 100000
+Global $aFields[100][100][2]
+Global $iDelayStep = 10  ; stop between steps in msec
+
+Global $aDirection[4][4] = [ _ ; [ direction 0-3 ][ left change x, y, right change x, y ]
+[-1,  0, +1,  0], _   ; == direction 0
+[ 0, -1,  0, +1], _   ; == direction 1
+[+1,  0, -1,  0], _   ; == direction 2
+[ 0, +1,  0, -1]]     ; == direction 3
+
+Global $hGui = GUICreate("Langton's ant", 100*8, 100*8)
+GUISetBkColor(0xFFFFFF)
+
+For $i = 0 To 99
+	For $j = 0 To 99
+		$aFields[$i][$j][0] = GUICtrlCreateLabel('', $j*8, $i*8)
+		GUICtrlSetColor(-1, 0xFF0000)
+		$aFields[$i][$j][1] = 0
+	Next
+Next
+
+GUISetState()
+
+GUICtrlSetData($aFields[49][49][0], '#')
+
+Do
+	Sleep($iDelayStep)
+Until Not _SetAnt()
+
+Do
+Until GUIGetMsg() = -3
+
+
+Func _SetAnt()
+	Local Static $iRowLast = 49, $iColLast = 49, $iCount = 0
+	Local Static $aCol[2] = [0xFFFFFF,0x000000], $iDirection = 0
+	Local $iRow, $iCol, $fRight = False
+	If $iCount = $iCountMax Then Return 0
+
+	; == get current color
+	Local $iLastColor = $aFields[$iRowLast][$iColLast][1]
+
+	; == go to left/right
+	If $iLastColor = 0 Then $fRight = True
+
+	; == set the ant to the next field
+	Local $indexX = 0, $indexY = 1
+	If $fRight Then
+		$indexX = 2
+		$indexY = 3
+	EndIf
+	$iRow = $iRowLast + ($aDirection[$iDirection][$indexX])
+	$iCol = $iColLast + ($aDirection[$iDirection][$indexY])
+	If $iRow < 0 Or $iRow > 99 Or $iCol < 0 Or $iCol > 99 Then Return 0
+	GUICtrlSetData($aFields[$iRowLast][$iColLast][0], '')
+	GUICtrlSetData($aFields[$iRow][$iCol][0], '#')
+
+	; == direction for next step
+	If $fRight Then
+		$iDirection += 1
+		If $iDirection = 4 Then $iDirection = 0
+	Else
+		$iDirection -= 1
+		If $iDirection = -1 Then $iDirection = 3
+	EndIf
+
+	; == change the color of the current field
+	GUICtrlSetBkColor($aFields[$iRowLast][$iColLast][0], $aCol[(Not $iLastColor)*1])
+	$aFields[$iRowLast][$iColLast][1] = (Not $iLastColor)*1
+
+	$iRowLast = $iRow
+	$iColLast = $iCol
+	$iCount += 1
+	WinSetTitle($hGui, '', "Langton's ant      [ step: " & StringFormat('%06d', $iCount) & " ]")
+	Return 1
+EndFunc  ;==>_SetAnt

Task/Langtons-ant/Perl/langtons-ant.pl

@@ -21,7 +21,7 @@ my $dir = int rand @dirs;
 my $move;
 for ($move = 0; $x >= 0 && $x < $size && $y >= 0 && $y < $size; $move++) {
   # toggle cell's value (white->black or black->white)
-  if ($plane[$x][$y] = 1 - $plane[$x][$y]) {
+  if ($plane[$x][$y] = 1 - ($plane[$x][$y] ||= 0)) {
         # if it's now true (black), then it was white, so turn right
         $dir = ($dir - 1) % @dirs;
   } else {

Task/Langtons-ant/Processing/langtons-ant

@@ -1,6 +1,6 @@
 /*
  * we use the following conventions:
- * directions 0: up, 1: right, 2: down: 3: left
+ * directions 0: up, 1: left, 2: down: 3: right
  *
  * pixel white: true, black: false
  *
@@ -36,7 +36,7 @@ int count=0;
 void draw() {
   for(int i=0;i<STEP;i++) {
     count++;
-    boolean pix=get(x,y)!=-1;
+    boolean pix=get(x,y)!=-1; //white =-1
     setBool(x,y,pix);
 
     turn(pix);
@@ -59,13 +59,13 @@ void move() {
       y--;
       break;
     case 1:
-      x++;
+      x--;
       break;
     case 2:
       y++;
       break;
     case 3:
-      x--;
+      x++;
       break;
   }
 }

Task/Langtons-ant/R/langtons-ant.r

@@ -0,0 +1,20 @@
+langton.ant = function(n = 100) {
+	map = matrix(data = 0, nrow = n, ncol = n)
+	p = floor(c(n/2, n/2))
+	d = sample(1:4, 1)
+	i = 1
+	while(p[1] > 0 & p[1] <= n & p[2] > 0 & p[2] <= n) {
+		if(map[p[1], p[2]] == 1) {
+			map[p[1], p[2]] = 0
+			p = p + switch(d, c(0, 1), c(-1, 0), c(0, -1), c(1, 0))
+			d = ifelse(d == 4, 1, d + 1)
+		} else {
+			map[p[1], p[2]] = 1
+			p = p + switch(d, c(0, -1), c(1, 0), c(0, 1), c(-1, 0))
+			d = ifelse(d == 1, 4, d - 1)
+		}
+	}
+	return(map)
+}
+
+image(langton.ant(), xaxt = "n", yaxt = "n", bty = "n")