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From: Maria Stylianou <marsty5@gmail.com>
Date: Thu, 30 May 2013 12:53:33 +0200
Message-ID: 
 <CAOJWUPYWKTkt203MMB3T4y7Dn8JuL2MqkspM-7xfxXT4+3iOWQ@mail.gmail.com>
Subject: SimplePageRankComputation - The Reader behaves not as expected
To: user@giraph.apache.org
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Hey guys,

I was playing with PageRank these days, and had some weird results.
I wanted to use the Input Format Reader and Output Format Writer given
inside SimplePageRankComputation, so I gave my input file and called the
specific code in the command line.

Some of the vertices got value > 1. So I had a look in the logs, and
noticed that it is generating its own vertices and my input file is never
used.
The Vertex class inside the SimplePageRankVertexReader has the following
lines:
LongWritable vertexId = new LongWritable(
          (inputSplit.getSplitIndex() * totalRecords) + recordsRead);
      DoubleWritable vertexValue = new DoubleWritable(vertexId.get() * 10d);
      long targetVertexId =
          (vertexId.get() + 1) %
          (inputSplit.getNumSplits() * totalRecords);
      float edgeValue = vertexId.get() * 100f;

And in the Task Logs, it prints

2013-05-30 11:28:20,808 INFO
org.apache.giraph.examples.SimplePageRankVertex$SimplePageRankVertexReader:
next: Return vertexId=0, vertexValue=0.0, targetVertexId=1,
edgeValue=0.0
2013-05-30 11:28:20,809 INFO
org.apache.giraph.examples.SimplePageRankVertex$SimplePageRankVertexReader:
next: Return vertexId=1, vertexValue=10.0, targetVertexId=2,
edgeValue=100.0
2013-05-30 11:28:20,809 INFO
org.apache.giraph.examples.SimplePageRankVertex$SimplePageRankVertexReader:
next: Return vertexId=2, vertexValue=20.0, targetVertexId=3,
edgeValue=200.0
2013-05-30 11:28:20,809 INFO
org.apache.giraph.examples.SimplePageRankVertex$SimplePageRankVertexReader:
next: Return vertexId=3, vertexValue=30.0, targetVertexId=4,
edgeValue=300.0
2013-05-30 11:28:20,809 INFO
org.apache.giraph.examples.SimplePageRankVertex$SimplePageRankVertexReader:
next: Return vertexId=4, vertexValue=40.0, targetVertexId=5,
edgeValue=400.0
2013-05-30 11:28:20,809 INFO
org.apache.giraph.examples.SimplePageRankVertex$SimplePageRankVertexReader:
next: Return vertexId=5, vertexValue=50.0, targetVertexId=6,
edgeValue=500.0
2013-05-30 11:28:20,809 INFO
org.apache.giraph.examples.SimplePageRankVertex$SimplePageRankVertexReader:
next: Return vertexId=6, vertexValue=60.0, targetVertexId=7,
edgeValue=600.0
2013-05-30 11:28:20,810 INFO
org.apache.giraph.examples.SimplePageRankVertex$SimplePageRankVertexReader:
next: Return vertexId=7, vertexValue=70.0, targetVertexId=8,
edgeValue=700.0
2013-05-30 11:28:20,810 INFO
org.apache.giraph.examples.SimplePageRankVertex$SimplePageRankVertexReader:
next: Return vertexId=8, vertexValue=80.0, targetVertexId=9,
edgeValue=800.0
2013-05-30 11:28:20,810 INFO
org.apache.giraph.examples.SimplePageRankVertex$SimplePageRankVertexReader:
next: Return vertexId=9, vertexValue=90.0, targetVertexId=0,
edgeValue=900.0


Could someone explain why is this happening?
Thanks!
-- 
Maria Stylianou
Intern at Telefonica, Barcelona, Spain
Master Student of European Master in Distributed
Computing<http://www.kth.se/en/studies/programmes/master/em/emdc>
marsty5.wordpress.com

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Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr">Hey guys,<div><br></div><div>I was playing with PageRank t=
hese days, and had some weird results.=A0</div><div>I wanted to use the Inp=
ut Format Reader and Output Format Writer given inside SimplePageRankComput=
ation, so I gave my input file and called the specific code in the command =
line. =A0<br clear=3D"all">

<div><br></div><div style>Some of the vertices got value &gt; 1. So I had a=
 look in the logs, and noticed that it is generating its own vertices and m=
y input file is never used.</div><div style>The Vertex class inside the=A0S=
implePageRankVertexReader has the following lines:</div>

<div style><div><font face=3D"verdana, sans-serif">LongWritable vertexId =
=3D new LongWritable(</font></div><div><font face=3D"verdana, sans-serif">=
=A0 =A0 =A0 =A0 =A0 (inputSplit.getSplitIndex() * totalRecords) + recordsRe=
ad);</font></div>

<div><font face=3D"verdana, sans-serif">=A0 =A0 =A0 DoubleWritable vertexVa=
lue =3D new DoubleWritable(vertexId.get() * 10d);</font></div><div><font fa=
ce=3D"verdana, sans-serif">=A0 =A0 =A0 long targetVertexId =3D</font></div>=
<div><font face=3D"verdana, sans-serif">=A0 =A0 =A0 =A0 =A0 (vertexId.get()=
 + 1) %</font></div>

<div><font face=3D"verdana, sans-serif">=A0 =A0 =A0 =A0 =A0 (inputSplit.get=
NumSplits() * totalRecords);</font></div><div><font face=3D"verdana, sans-s=
erif">=A0 =A0 =A0 float edgeValue =3D vertexId.get() * 100f;</font></div></=
div><div style><br>

</div><div style>And in the Task Logs, it prints</div><div style><pre style=
=3D"color:rgb(0,0,0)"><font face=3D"courier new, monospace">2013-05-30 11:2=
8:20,808 INFO org.apache.giraph.examples.SimplePageRankVertex$SimplePageRan=
kVertexReader: next: Return vertexId=3D0, vertexValue=3D0.0, targetVertexId=
=3D1, edgeValue=3D0.0
2013-05-30 11:28:20,809 INFO org.apache.giraph.examples.SimplePageRankVerte=
x$SimplePageRankVertexReader: next: Return vertexId=3D1, vertexValue=3D10.0=
, targetVertexId=3D2, edgeValue=3D100.0
2013-05-30 11:28:20,809 INFO org.apache.giraph.examples.SimplePageRankVerte=
x$SimplePageRankVertexReader: next: Return vertexId=3D2, vertexValue=3D20.0=
, targetVertexId=3D3, edgeValue=3D200.0
2013-05-30 11:28:20,809 INFO org.apache.giraph.examples.SimplePageRankVerte=
x$SimplePageRankVertexReader: next: Return vertexId=3D3, vertexValue=3D30.0=
, targetVertexId=3D4, edgeValue=3D300.0
2013-05-30 11:28:20,809 INFO org.apache.giraph.examples.SimplePageRankVerte=
x$SimplePageRankVertexReader: next: Return vertexId=3D4, vertexValue=3D40.0=
, targetVertexId=3D5, edgeValue=3D400.0
2013-05-30 11:28:20,809 INFO org.apache.giraph.examples.SimplePageRankVerte=
x$SimplePageRankVertexReader: next: Return vertexId=3D5, vertexValue=3D50.0=
, targetVertexId=3D6, edgeValue=3D500.0
2013-05-30 11:28:20,809 INFO org.apache.giraph.examples.SimplePageRankVerte=
x$SimplePageRankVertexReader: next: Return vertexId=3D6, vertexValue=3D60.0=
, targetVertexId=3D7, edgeValue=3D600.0
2013-05-30 11:28:20,810 INFO org.apache.giraph.examples.SimplePageRankVerte=
x$SimplePageRankVertexReader: next: Return vertexId=3D7, vertexValue=3D70.0=
, targetVertexId=3D8, edgeValue=3D700.0
2013-05-30 11:28:20,810 INFO org.apache.giraph.examples.SimplePageRankVerte=
x$SimplePageRankVertexReader: next: Return vertexId=3D8, vertexValue=3D80.0=
, targetVertexId=3D9, edgeValue=3D800.0
2013-05-30 11:28:20,810 INFO org.apache.giraph.examples.SimplePageRankVerte=
x$SimplePageRankVertexReader: next: Return vertexId=3D9, vertexValue=3D90.0=
, targetVertexId=3D0, edgeValue=3D900.0</font></pre></div><div><br></div><d=
iv style>

Could someone explain why is this happening? =A0</div><div style>Thanks!</d=
iv>-- <br><div dir=3D"ltr">Maria Stylianou<div>Intern at Telefonica, Barcel=
ona, Spain</div><div>Master Student of <a href=3D"http://www.kth.se/en/stud=
ies/programmes/master/em/emdc" target=3D"_blank">European Master in Distrib=
uted Computing</a><div>

<a href=3D"http://marsty5.wordpress.com" target=3D"_blank">marsty5.wordpres=
s.com</a></div><div><br></div></div></div>
</div></div>

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