Yeah he is right, we should modify this. I always wondered where this 0.15 came from. Thank you very much :)
2011/6/24 Edward J. Yoon <[email protected]> > Just FYI, > > As mentioned below, hard-coded default value for alpha (0.15) should > be replaced. > > ---------- Forwarded message ---------- > From: Yunkai Zhang <[email protected]> > Date: Fri, Jun 24, 2011 at 9:51 AM > Subject: A bug in the PageRank example > To: [email protected] > > > Hi, > > I am playing with the pagerank example from trunk and found there is a bug > in the code. > If I assign any value other than 0.85 to the damping factor, the results > won't sum to 1. > > For example: Set damping factor to *0.5* > > 11/06/23 17:28:05 INFO graph.PageRankBase: -------------------- RESULTS > -------------------- > 11/06/23 17:28:06 INFO graph.PageRankBase: stackoverflow.com | > 0.052213531500120945 > 11/06/23 17:28:06 INFO graph.PageRankBase: nasa.gov | 0.04235399497763073 > 11/06/23 17:28:06 INFO graph.PageRankBase: facebook.com | > 0.030321424044325564 > 11/06/23 17:28:06 INFO graph.PageRankBase: yahoo.com | 0.05650175656380897 > 11/06/23 17:28:07 INFO graph.PageRankBase: youtube.com | > 0.025716796492259456 > 11/06/23 17:28:07 INFO graph.PageRankBase: google.com | > 0.07350857237752877 > 11/06/23 17:28:07 INFO graph.PageRankBase: twitter.com | > 0.030321424044325564 > > The sum is 0.3ish. > > Therefore, I read the code. I think a possible reason is that the value of > * > ALPHA* is hard-coded. (Formula: P(i) = ALPHA + 0.85 * sum, ALPHA = 0.15 / > NumVertices() ) > In PageRank.java, line 167: ALPHA = *0.15* / (double) numOfVertices; > > I think 0.15 should be replaced by (1 - DAMPING_FACTOR). > > > > Thanks! > > > > Best, > Benny > > > > -- > Best Regards, Edward J. Yoon > @eddieyoon > -- Thomas Jungblut Berlin mobile: 0170-3081070 business: [email protected] private: [email protected]
