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June 2015

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Subject:
From:
Sean Luke <[log in to unmask]>
Reply To:
MASON Multiagent Simulation Toolkit <[log in to unmask]>
Date:
Mon, 15 Jun 2015 15:59:50 -0400
Content-Type:
text/plain
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text/plain (66 lines)
MASON actually has a MutableDouble.

java/mason/sim/util/MutableDouble.java

You could use that. Also, don't use for(Object object : objects) -- it translates to building an Iterator, and at least as of Java 7 Iterators are still quite slow.

I'd do this:

       final public void SparseGrid2DMultiply(SparseGrid2D theGrid, double multiplier) {
               Bag objects = theGrid.getAllObjects();
int len = objects.size();
for(int i = 0; i < len; i++)
{
MutableDouble d = (MutableDouble)(objects.get(i));
d.val *= multiplier;
}
}


On Jun 15, 2015, at 1:02 PM, Sadat Chowdhury <[log in to unmask]> wrote:

> I still have a lot of files to change, and have not actually run/tested with this new method ó maybe it would throw the ConcurrentModificationException, I donít know yet.
>
> I am going to look into MutableDouble ó 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 ó 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 ó I am at a point where I have a lot of DoubleGrid2Dís 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.

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