Hi Vasia,
okay I understand now :)
So it works fine if I want to collect the sum of values.
But what if I need to reset the DoubleSumAggregator back to 0 in order to then
set it to a new value to save the absolute maximum?
Please have a look at the code above.
Any idea why it is not working?
public static class VertexDistanceUpdater extends VertexUpdateFunction<Integer,
Double, Double> {
DoubleSumAggregator aggregator = new DoubleSumAggregator();
public void preSuperstep() {
// retrieve the Aggregator
aggregator = getIterationAggregator("sumAggregator");
}
public void updateVertex(Vertex<Integer, Double> vertex,
MessageIterator<Double> inMessages) {
double sum = 0;
for (double msg : inMessages) {
sum = sum + (msg);
}
if((Math.abs(sum) > Math.abs(aggregator.getAggregate().getValue()))){
aggregator.reset();
aggregator.aggregate(sum);
}
setNewVertexValue(sum);
}
}
> Am 13.05.2016 um 09:25 schrieb Vasiliki Kalavri <vasilikikala...@gmail.com>:
>
> Hi Lydia,
>
> an iteration aggregator combines all aggregates globally once per superstep
> and makes them available in the *next* superstep.
> Within each scatter-gather iteration, one MessagingFunction (scatter phase)
> and one VertexUpdateFunction (gather phase) are executed. Thus, if you set an
> aggregate value within one of those, the value will be available in the next
> superstep. You can retrieve it calling the getPreviousIterationAggregate()
> method.
> Let me know if that clears things up!
>
> -Vasia.
>
> On 13 May 2016 at 08:57, Lydia Ickler <ickle...@googlemail.com
> <mailto:ickle...@googlemail.com>> wrote:
> Hi Vasia,
>
> yes, but only independently within each Function or not?
>
> If I set the aggregator in VertexUpdateFunction then the newly set value is
> not visible in the MessageFunction.
> Or am I doing something wrong? I would like to have a shared aggregator to
> normalize vertices.
>
>
>> Am 13.05.2016 um 08:04 schrieb Vasiliki Kalavri <vasilikikala...@gmail.com
>> <mailto:vasilikikala...@gmail.com>>:
>>
>> Hi Lydia,
>>
>> registered aggregators through the ScatterGatherConfiguration are accessible
>> both in the VertexUpdateFunction and in the MessageFunction.
>>
>> Cheers,
>> -Vasia.
>>
>> On 12 May 2016 at 20:08, Lydia Ickler <ickle...@googlemail.com
>> <mailto:ickle...@googlemail.com>> wrote:
>> Hi,
>>
>> I have a question regarding the Aggregators of a Scatter-Gather Iteration.
>> Is it possible to have a global aggregator that is accessible in
>> VertexUpdateFunction() and MessagingFunction() at the same time?
>>
>> Thanks in advance,
>> Lydia
>>
>
>
