View difference between Paste ID: xa5cgLwF and rBmYn6R1

-simpleDeltas =: (1 0),(0 _1),(_1 0),,:(0 1)
+NB. true for rows in x which index true value in y
-eightdirDeltas =: (_1 1),(_1 _1),(1 _1),(1 1),simpleDeltas
+validIn =: (<"1@(|~ #) { ]) *. (|~ #) -:"1 [
 
-indexOutOfBounds =: (0 > ]) +./@:, <: NB. x={vect}shapeOfArray, y={vect}index; z=bit
+filter =: 1 : '#~ u' NB. removes all elements of y where u(y[i]) is false
 
-atIndex =: ({~ <@:|.)"_ 1 NB. equivalent of x[y2][...][y0] in C-style language
+
 manhattanDeltas=: 3 :'(,-)=i.#$y' NB. unit vectors oriented on coordinate axes
-filter =: 1 : '((0~:u)"_1 y) # y' NB. removes all elements of y where u(y[i]) = 0
+
 NB. x = [[bit]]  valid squares
 NB. y = [num]    index
 NB. z = [[num]]  neighbors
-shuffle =: (#?#) { ]
+gridNeighbors =: 1 : 0
     [: validIn&m filter (manhattanDeltas m) +"1 ]
 )
 
 NB. m = [[bit]]        valid squares
-gridNeighbors =: 4 : 0
+
-	neighbors =. simpleDeltas +"1 y
+
-	neighbors =. (-.@(($x)&indexOutOfBounds)) filter neighbors NB. remove those leaving the grid
+
-	neighbors =. x&atIndex filter neighbors NB. remove those entering a wall
+    > <@,"_ 1 m gridNeighbors@{:@>
 )
 
-NB. Path<T> =: [{boxed num}distance, {boxed [T]}path]
+
 NB. u = (Path<Node>)->[Path<Node>]  extendPath
 NB. v = (Node,Node)->num            heuristicDist
 NB. y = Node                        start
 NB. z = Path<Node>                  shortest path
 aStar =: 2 : 0
-	newDist  =. 1 + > {. y
+
-	path     =. > {: y
+
-	lastPos  =. {: path
+	frontier =. ,<,:y
-	newPoses =. m gridNeighbors lastPos
+
-	newPaths =. path ,"_ 1 newPoses
+
-	(newDist ; <)"_1 newPaths
+
 		last        =. {: > currentPath
 		if. last e. closed do. continue.            end.
 		if. last -: x      do. >currentPath return. end.
 		closed   =. closed, last
 		frontier =. frontier, u currentPath
 		NB. SORT FRONTIER
 		scores   =. (# +  x v {:)&> frontier
 		frontier =. frontier /: scores
 	end.
 	exception_message=:'No path found.' throw.
-	frontier =. ,: 0;<,:y
+
 
 exampleG =: '#' = ];._2]0 :0
 ....##..##
-		last        =. {: > {: currentPath
+.##.##..##
-		if. last e. closed do. continue.           end.
+#..#####..
-		if. last -: x      do. currentPath return. end.
+#.#...##..
 .##...###.
-		frontier =. frontier, (u currentPath)
+.##.####.#
 ..#..##.#.
-		scores   =. (>@{. + (x v {:@:>@:{:))"_1 frontier
+###.##..##
 #.#####..#
 ...####..#
 )
 
 exampleSolution =: 0 8 (((|:exampleG) gridExtendPath) aStar manhattanDistance) 5 0
-exampleG =: 10 10 $ (0 0 0 0 1 1 0 0 1 1 0 1 1 0 1 1 0 0 1 1 1 0 0 1 1 1 1 1 0 0 1 0 1 0 0 0 1 1 0 0 0 1 1 0 0 0 1 1 1 0 0 1 1 0 1 1 1 1 0 1 0 0 1 0 0 1 1 0 1 0 1 1 1 0 1 1 0 0 1 1 1 0 1 1 1 1 1 0 0 1 0 0 0 1 1 1 1 0 0 1)
+
-exampleSolution =: 0 8 ((exampleG gridExtendPath) aStar manhattanDistance) 5 0
+NB. to inspect this solution, use:
    '*' (<"1 exampleSolution)} '.#' {~ |:exampleG
 
 NB. or
 
    '*' (<@|."1 exampleSolution)} '.#' {~ exampleG