Hi Claudio, So I checked out TextAggregatorWriter and was, initially, still a bit confused on how to use it to write to a text file. That's when I noticed that, in org.apache.giraph.utils.ConfigurationUtils, there is an option "aw", which corresponds to an AggregatorWriterClass. I tried this out when running the SimplePageRankComputation program using my data as input by specifying this as an option:
-aw org.apache.giraph.aggregators.TextAggregatorWriter. Here's the full command: hadoop jar /home/hduser/Documents/combined.jar org.apache.giraph.GiraphRunner org.apache.giraph.examples.SimplePageRankComputation -eif StackExchangeParsee.StackExchangeLongFloatTextEdgeInput -vif StackExchangeParsee.StackExchangeLongDoubleTextVertexValueInput -eip /in/gaming_edges.txt -vip /in/gaming_vertices.txt -of org.apache.giraph.io.formats.IdWithValueTextOutputFormat -aw org.apache.giraph.aggregators.TextAggregatorWriter -op /outPR -w 2 -mc org.apache.giraph.examples.SimplePageRankComputation\$SimplePageRankMasterCompute According to TextAggregatorWriter, it, by default, writes to a file called "aggregatorValues". I checked my HDFS, and did not see that particular file. That's when I noticed that there is a configuration "giraph.textAggregatorWriter.frequency", and that by default the frequency is set to "NEVER", which means that nothing is ever created/written to a file for the aggregators. The other two frequencies are "AT_THE_END" and "ALWAYS", which strangely both correspond to the same integer: -1. Could someone explain why this is so? Ignoring the above uncertainty, I surmised that the property "giraph.textAggregatorWriter.frequency" was to be added to my giraph-site.xml. I wanted the "AT_THE_END" frequency, which corresponds to the value of -1. Here's the contents of my giraph-site.xml file: <configuration> <property> <name>giraph.textAggregatorWriter.frequency</name> <value>-1</value> </property> </configuration> I ran the SimplePageRankComputation program again (using the verbose "hadoop jar" command above), and still, I couldn't find "aggregatorValues" on my HDFS. Could someone help me out, or at the very least rectify any misconceptions and uncertainties that I have? On Wed, Jul 24, 2013 at 12:25 PM, Claudio Martella <claudio.marte...@gmail.com> wrote: > Hi Kyle, > > you can check out the AggregatorWriter interface which allows you to do > that. As a matter of fact there is already a class that implements what you > need (org.apache.giraph.aggregators.TextAggregatorWriter). > > Hope it helps. > > > On Wed, Jul 24, 2013 at 5:19 PM, Kyle Orlando <kyle.r.orla...@gmail.com> > wrote: >> >> Hello, >> >> I am new to Giraph and was just wondering how one could retrieve and >> display the certain global values/statistics that the aggregators keep >> track of. What classes and methods would I use, and would this be >> done in a class that extends VertexOutputFormat, or would it be done >> elsewhere? >> >> As an example, in the provided SimplePageRankComputation in >> org.apache.giraph.examples, there are three aggregators: sum, min, and >> max. I would like to display all of their final values (after the >> final superstep) in some way, such as writing them to a text file. >> >> -- >> Kyle Orlando >> Computer Engineering Major >> University of Maryland > > > > > -- > Claudio Martella > claudio.marte...@gmail.com -- Kyle Orlando Computer Engineering Major University of Maryland