diff -u -r1.8 -r1.9
--- CellReadout.hh	6 Sep 2013 02:17:48 -0000	1.8
+++ CellReadout.hh	6 Sep 2013 03:29:23 -0000	1.9
@@ -1,4 +1,4 @@

-// $Header: /cvs/lcd/lcdd/include/lcdd/detectors/CellReadout.hh,v 1.8 2013/09/06 02:17:48 jeremy Exp $

+// $Header: /cvs/lcd/lcdd/include/lcdd/detectors/CellReadout.hh,v 1.9 2013/09/06 03:29:23 jeremy Exp $

 
 #ifndef LCDD_DETECTORS_CELLREADOUT_HH
 #define LCDD_DETECTORS_CELLREADOUT_HH 1

@@ -18,7 +18,6 @@

 public:
 
     /** A 2D position, which will usually be XY in the local coordinate system. */

-    //typedef std::pair<double, double> Position2D;

     struct Position2D
     {
         double x;

@@ -31,9 +30,6 @@

     /** A list of a cell's neighbor IDs. */
     typedef std::vector<CellId> Neighbors;
 

-    /** A list of the field names for this readout. */
-    //typedef std::vector<std::string> FieldNames;
-

 public:
 
     /**

@@ -66,17 +62,6 @@

      * @return The list of Neighbors for the given CellId.
      */
     virtual Neighbors neighbors(CellId id) = 0;

-
-    /**
-     * Get the list of field names.
-     * @return The list of field names defined by the readout.
-     */
-    //const FieldNames& fieldNames();
-
-//protected:
-
-    /** The list of field names. */
-    //FieldNames _fieldNames;

 };
 
 #endif

diff -u -r1.7 -r1.8
--- CellReadout2D.hh	6 Sep 2013 02:17:48 -0000	1.7
+++ CellReadout2D.hh	6 Sep 2013 03:29:23 -0000	1.8
@@ -1,4 +1,4 @@

-// $Header: /cvs/lcd/lcdd/include/lcdd/detectors/CellReadout2D.hh,v 1.7 2013/09/06 02:17:48 jeremy Exp $

+// $Header: /cvs/lcd/lcdd/include/lcdd/detectors/CellReadout2D.hh,v 1.8 2013/09/06 03:29:23 jeremy Exp $

 
 #ifndef LCDD_DETECTORS_CELLREADOUT2D_HH
 #define LCDD_DETECTORS_CELLREADOUT2D_HH 1

@@ -54,6 +54,8 @@

 
     /**
      * ----------------------------------------------------------

+     * Functionality specific to this implementation.
+     * ----------------------------------------------------------

      */
 
     /**

@@ -142,6 +144,20 @@

      */
     double getDimensionY();
 

+    /**
+     * Check if a CellId is valid.
+     * @param[in] The CellId to check.
+     * @return True if valid; false if not.
+     */
+    bool isValidCell(CellId cell);
+
+    /**
+     * Check if a Position2D is valid.
+     * @param[in] The position to check.
+     * @return True if valid; false if not.
+     */
+    bool isValidPosition(Position2D position);
+

 private:
 
     double _cellSizeX;

diff -u -r1.3 -r1.4
--- CellReadout2D.cc	6 Sep 2013 02:17:48 -0000	1.3
+++ CellReadout2D.cc	6 Sep 2013 03:29:23 -0000	1.4
@@ -1,4 +1,4 @@

-// $Header: /cvs/lcd/lcdd/src/lcdd/detectors/CellReadout2D.cc,v 1.3 2013/09/06 02:17:48 jeremy Exp $

+// $Header: /cvs/lcd/lcdd/src/lcdd/detectors/CellReadout2D.cc,v 1.4 2013/09/06 03:29:23 jeremy Exp $

 
 // LCDD
 #include "lcdd/detectors/CellReadout2D.hh"

@@ -9,12 +9,8 @@

 #include <stdexcept>
 
 CellReadout2D::CellReadout2D(double cellSizeX, double cellSizeY)

+    : _cellSizeX(cellSizeX), _cellSizeY(cellSizeY), _dimensionX(0.), _dimensionY(0.)

 {

-    _cellSizeX = cellSizeX;
-    _cellSizeY = cellSizeY;
-
-    //_fieldNames.push_back("ix");
-    //_fieldNames.push_back("iy");

 }
 
 CellReadout2D::~CellReadout2D()

@@ -34,80 +30,28 @@

     return createCell(getXIndex(position.x), getYIndex(position.y));
 }
 

-/**
- * Create a list of neighbor cells from a cell ID.
- */

 CellReadout::Neighbors CellReadout2D::neighbors(CellId cellId)
 {
     Neighbors neighbors;

+    CellId cell;

-    /*
-    int ix, iy;
-
-    // top left
-    ix = cellId[0] - 1;
-    if (ix == 0)
-        ix = -1;
-    iy = cellId[1] + 1;
-    if (iy == 0)
-        iy = 1;
-    neighbors.push_back(createCell(ix, iy));
-
-    // top middle
-    ix = cellId[0];
-    iy = cellId[1] + 1;
-    if (iy == 0)
-        iy = 1;
-    neighbors.push_back(createCell(ix, iy));
-
-    // top right
-    ix = cellId[0];
-    if (ix == 0)
-        ix = 1;
-    iy = cellId[1] + 1;
-    if (iy == 0)
-        iy = 1;
-    neighbors.push_back(createCell(ix, iy));
-
-    // middle left
-    ix = cellId[0] - 1;
-    if (ix == 0)
-        ix = -1;
-    iy = cellId[1];
-    neighbors.push_back(createCell(ix, iy));
-
-    // middle right
-    ix = cellId[0] + 1;
-    if (ix == 0)
-        ix = 1;
-    iy = cellId[1];
-    neighbors.push_back(createCell(ix, iy));
-
-    // bottom left
-    ix = cellId[0] - 1;
-    if (ix == 0)
-        ix = -1;
-    iy = cellId[1] - 1;
-    if (iy == 0)
-        iy = -1;
-    neighbors.push_back(createCell(ix - 1, iy - 1));
-
-    // bottom middle
-    ix = cellId[0];
-    iy = cellId[1] - 1;
-    if (iy == 0)
-        iy = -1;
-    neighbors.push_back(createCell(ix, iy - 1));
-
-    // bottom right
-    ix = cellId[0] + 1;
-    if (ix == 0)
-        ix = 1;
-    iy = cellId[1] - 1;
-    if (iy == 0)
-        iy = -1;
-    neighbors.push_back(createCell(ix, iy - 1));
-    */

+    // Loop over delta Y.
+    for (int i = -1; i <= 1; i++) {
+        // Loop over delta X.
+        for (int j = -1; j <= 1; j++) {
+            // Ignore this cell.
+            if (i != 0 || j != 0) {
+                // Create CellId for this neighbor.
+                std::cout << "creating neighbor i, j: " << i << ", " << j << std::endl;
+                cell = createCell(cellId[0] + j, cellId[1] + i);
+                // Check if valid.
+                if (isValidCell(cell)) {
+                    // Add if cell is valid.
+                    neighbors.push_back(cell);
+                }
+            }
+        }
+    }

 
     return neighbors;
 

@@ -184,3 +128,34 @@

     return _dimensionY;
 }
 

+bool CellReadout2D::isValidCell(CellId cell)
+{
+    // DEBUG
+    std::cout << "isValidCell: " << cell[0] << ", " << cell[1] << std::endl;
+
+    if (cell[0] <= 0 || cell[1] <= 0) {
+        std::cout << "field value < 0" << std::endl;
+        return false;
+    }
+    int xmax = std::floor(getDimensionX() / getCellSizeX());
+    std::cout << "xmax: " << xmax << std::endl;
+    if (cell[0] > xmax) {
+        std::cout << cell[0] << " exceeds max allowed X index" << std::endl;
+        return false;
+    }
+    int ymax = std::floor(getDimensionY() / getCellSizeY());
+    std::cout << "ymax: " << ymax << std::endl;
+    if (cell[1] > ymax) {
+        std::cout << cell[1] << " exceeds max allowed Y index" << std::endl;
+        return false;
+    }
+    return true;
+}
+
+bool CellReadout2D::isValidPosition(Position2D position)
+{
+    if (position.x > getDimensionX() || position.x < 0) return false;
+    if (position.y > getDimensionY() || position.y < 0) return false;
+    return true;
+}
+

diff -u -r1.5 -r1.6
--- CellReadout2DSegmentation.cc	6 Sep 2013 02:17:48 -0000	1.5
+++ CellReadout2DSegmentation.cc	6 Sep 2013 03:29:23 -0000	1.6
@@ -1,4 +1,4 @@

-// $Header: /cvs/lcd/lcdd/src/lcdd/detectors/CellReadout2DSegmentation.cc,v 1.5 2013/09/06 02:17:48 jeremy Exp $

+// $Header: /cvs/lcd/lcdd/src/lcdd/detectors/CellReadout2DSegmentation.cc,v 1.6 2013/09/06 03:29:23 jeremy Exp $

 
 // LCDD
 #include "lcdd/detectors/CellReadout2DSegmentation.hh"

@@ -124,6 +124,14 @@

     this->setBin(0, cellPosition.x);
     this->setBin(1, cellPosition.y);
 

+    // DEBUG
+    // print the neighbor CellIds
+    CellReadout::Neighbors neighbors = _readout->neighbors(cell);
+    std::cout << "neighbors: " << std::endl;
+    for (CellReadout::Neighbors::const_iterator it = neighbors.begin(); it != neighbors.end(); it++) {
+        std::cout << "  " << (*it)[0] << ", " << (*it)[1] << std::endl;
+    }
+

     std::cout << std::endl;
 }