Thanks for your report! Please feel free to file JIRA issue - https://issues.apache.org/jira/browse/HAMA
On Fri, Jun 24, 2011 at 9:51 AM, Yunkai Zhang <[email protected]> wrote: > 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
