Merge pull request #4 from possibly/master

Small patch, better README, areNeighbors()

Author: tillarnold

README.md

@@ -61,17 +61,54 @@ Example, distance = 2:
 
 The function will return an array containing the values for the fields marked with an '*'. Notice that distance will change what cells count as neighbors.
 
+### areNeighbours(x1, y1, x2, y2, [, distance])
+Returns true if the given coordinates are neighbors, false otherwise.
+
+The distance between each coordinate must be within `distance` or one unit away from each other for the
+given coordinates to be considered neighbors.
+
+For example, distance not set:
+
+```
+   0  1  2 
+0 [A][ ][ ]
+1 [ ][B][ ]
+2 [ ][ ][ ]
+3 [ ][ ][ ]
+```
+
+The first given coordinate (0,0) is marked with an `A`, the second (1,1), a `B`.
+A and B are neighbors.
+
+If A and B were instead placed at (0,0) and (2,2) respectively, like this:
+
+```
+   0  1  2 
+0 [A][ ][ ]
+1 [ ][ ][ ]
+2 [ ][ ][B]
+3 [ ][ ][ ]
+```
+
+A and B are no longer neighbors.
+
+Example, distance = 2:
+
+```
+   0  1  2 
+0 [A][ ][ ]
+1 [ ][ ][ ]
+2 [ ][ ][B]
+3 [ ][ ][ ]
+```
+
+A (0,0) and B (2,2) are neighbors.
+
 ### forEach(fn, [, thisArg])
 Executes a provided function once per array element.
 
 `fn` is the function to execute for each element, taking three arguments: 
-
-  currentValue
-    The current element being processed in the array.
-  index
-    The object index, {x: x, y: y}, of the current element being processed in the 2d array.
-  array
-    The Fixed2DArray that forEach is being applied to. 
-
-  thisArg 
-    Optional. Value to use as this when executing callback.
+  * `currentValue`: The current element being processed in the array.
+  * `index`: The object index, {x: x, y: y}, of the current element being processed in the 2d array.
+  * `array`: The Fixed2DArray that forEach is being applied to. 
+  * `thisArg`: Optional. Value to use as this when executing callback.

lib/fixed-2d-array.js

@@ -53,7 +53,7 @@ Fixed2DArray.prototype.getRow = function getRow(rowNumber){
  *
  * @param colNumber {number} number of the column where top left is (0,0).
  */
-Fixed2DArray.prototype.getColumn = function getRow(colNumber){
+Fixed2DArray.prototype.getColumn = function getColumn(colNumber){
   try{
     this.validateCoords(colNumber,0);
   } catch(err){
@@ -175,4 +175,63 @@ Fixed2DArray.prototype.getNeighbours = function getNeighbours(x, y, distance){
   return returnArray;
 };
 
+/**
+ * Returns true if the given coordinates are neighbors, false otherwise.
+ *
+ * The distance between each coordinate must be within `distance` or one unit away from 
+ * each other for the given coordinates to be considered neighbors.
+ *
+ * For example, distance not set:
+ *
+ *    0  1  2 
+ * 0 [A][ ][ ]
+ * 1 [ ][B][ ]
+ * 2 [ ][ ][ ]
+ * 3 [ ][ ][ ]
+ *
+ * The first given coordinate (0,0) is marked with an `A`, the second (1,1), a `B`.
+ * A and B are neighbors.
+ *
+ * If A and B were instead placed at (0,0) and (2,2) respectively, like this:
+ *
+ *    0  1  2 
+ * 0 [A][ ][ ]
+ * 1 [ ][ ][ ]
+ * 2 [ ][ ][B]
+ * 3 [ ][ ][ ]
+ *
+ * A and B are no longer neighbors.
+ *
+ * Example, distance = 2:
+ *
+ *    0  1  2 
+ * 0 [A][ ][ ]
+ * 1 [ ][ ][ ]
+ * 2 [ ][ ][B]
+ * 3 [ ][ ][ ]
+ *
+ * A (0,0) and B (2,2) are neighbors.
+ * 
+ * @param x1 {number} first x coordinate.
+ * @param y1 {number} first y coordinate.
+ * @param x2 {number} second x coordinate.
+ * @param y2 {number} second y coordinate.
+ * @param distance {number} Optional. Maximum distance for coordinates to be considered neighbors.
+ */
+Fixed2DArray.prototype.areNeighbours = function areNeighbours(x1, y1, x2, y2, distance){
+  this.validateCoords(x1,y1);
+  this.validateCoords(x2,y2);
+
+  if(typeof distance === 'undefined'){ distance = 1; } 
+  if(distance<=0){
+    return false;
+  }
+
+  if ( (Math.abs(x1 - x2) <= distance) && (Math.abs(y1 - y2) <= distance) ){
+    return true;
+  }else{
+    return false;
+  }
+};
+
 module.exports = Fixed2DArray;

test/test.js

@@ -69,3 +69,14 @@ test('get correct number of neighbours',function (t) {
   t.equal(fa.getNeighbours(2,2,-2).length,0);
 });
 
+test('areNeighbors',function (t) {
+  t.plan(6);
+  var fa = new fixedArray(10,10);
+  t.true(fa.areNeighbours(0,0,1,1));
+  t.false(fa.areNeighbours(0,0,2,2));
+  t.true(fa.areNeighbours(0,0,2,2,2));
+  t.throws(function(){fa.areNeighbours(-1,-1,0,0);});
+  t.throws(function(){fa.areNeighbours(0,0,-1,1);});
+  t.equal(fa.areNeighbours(0,0,1,1,0),false);
+});
+