I still have a lot of files to change, and have not actually run/tested with this new method — maybe it would throw the  ConcurrentModificationException, I don’t know yet.



I am going to look into MutableDouble — it makes more sense as far as accuracy goes. Thanks!





> On Jun 15, 2015, at 12:58 PM, Ernesto Carrella <[log in to unmask]> wrote:

> 

> You could try populating your SparseGrid2D with either an AtomicDouble or a MutableDouble from commons-lang. 

> That way you can modify them without pulling them out of the grid and putting them back in.

> 

> I am quite surprised it doesn't throw a ConcurrentModification exception since you are effectively looping through a list of objects that you are also modifying (with remove() and setLocation()). I suppose MASON passes a safe copy in that bag.

> 

> On Mon, Jun 15, 2015 at 5:23 PM Sadat Chowdhury <[log in to unmask]> wrote:

> Hi All,

> 

> When I increased the 2D world size of my system, there was a significant slowdown of the simulation. After I investigated using a profiler, it turned out to be due to methods that scan through 2D grids that in my system are defined as DoubleGrid2D.

> 

> I have started converting those DoubleGrid2D into SparseGrid2D — because it fits the description perfectly: the world can be potentially unbounded and most times there will be fewer actual objects in the world.

> 

> While it was relatively easy to convert all the parts that was setting and accessing objects in the grid — I am at a point where I have a lot of DoubleGrid2D’s that used full-scanning functions like .lowerBound() and .multiply(). Supposing I have a SparseGrid2D that has only one Double object per coordinate, what would be the most efficient (fast) way to implement a function similar to multiply() ?

> 

> This is what I have so far, but I am just wondering if it can be done more efficiently (faster)?

> 

>         final public void SparseGrid2DMultiply(SparseGrid2D theGrid,

>                         double multiplier) {

>                 /*

>                  * theGrid is assumed to contain one and only one Double in a given

>                  * coordinate

>                  */

>                 Bag objects = theGrid.getAllObjects();

>                 for (Object object : objects) {

>                         double val = (Double) object;

>                         if (val != 0.0) {

>                                 val = val * multiplier;

>                                 Int2D location = theGrid.getObjectLocation(object);

>                                 theGrid.remove(object);

>                                 theGrid.setObjectLocation(val, location);

>                         }

>                 }

> 

>         }

> 

> Any thoughts/comments is greatly appreciated,

> Sadat.