Generally adjacency matrix is undirected(symmetric) on social network, so you can get eigenvectors from SVD computed result.
A = UDV^t The first column of U is the biggest eigenvector corresponding to the first value of D. xj @ Tokyo On Sat, Aug 9, 2014 at 4:08 AM, Li Pu <l...@twitter.com.invalid> wrote: > @Miles, eigen-decomposition with asymmetric matrix doesn't always give > real-value solutions, and it doesn't have the nice properties that > symmetric matrix holds. Usually you want to symmetrize your asymmetric > matrix in some way, e.g. see > http://machinelearning.wustl.edu/mlpapers/paper_files/icml2005_ZhouHS05.pdf > but as Sean mentioned, you can always compute the largest eigenpair with > power method or some variations like pagerank, which is already implemented > in graphx. > > > On Fri, Aug 8, 2014 at 2:50 AM, Sean Owen <so...@cloudera.com> wrote: > >> The SVD does not in general give you eigenvalues of its input. >> >> Are you just trying to access the U and V matrices? they are also >> returned in the API. But they are not the eigenvectors of M, as you >> note. >> >> I don't think MLlib has anything to help with the general eigenvector >> problem. >> Maybe you can implement a sort of power iteration algorithm using >> GraphX to find the largest eigenvector? >> >> On Fri, Aug 8, 2014 at 4:07 AM, Chunnan Yao <yaochun...@gmail.com> wrote: >> > Hi there, what you've suggested are all meaningful. But to make myself >> > clearer, my essential problems are: >> > 1. My matrix is asymmetric, and it is a probabilistic adjacency matrix, >> > whose entries(a_ij) represents the likelihood that user j will >> broadcast the >> > information generated by user i. Apparently, a_ij and a_ji is different, >> > caus I love you doesn't necessarily mean you love me(What a sad >> story~). All >> > entries are real. >> > 2. I know I can get eigenvalues through SVD. My problem is I can't get >> the >> > corresponding eigenvectors, which requires solving equations, and I also >> > need eigenvectors in my calculation.In my simulation of this paper, I >> only >> > need the biggest eigenvalues and corresponding eigenvectors. >> > The paper posted by Shivaram Venkataraman is also concerned about >> symmetric >> > matrix. Could any one help me out? >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: user-unsubscr...@spark.apache.org >> For additional commands, e-mail: user-h...@spark.apache.org >> >> > > > -- > Li > @vrilleup >
