> while i'd expect from linlog something like an (x,y) coordinate. is > that correct?

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(x,y,z) is also common -- i think of it as extreme dimension reduction -- after which you're free to use your favorite gis tool -- http://postgis.refractions.net/ -- you can also pull in tools from statistical mechanics/thermodynamics Without complicating the algo for efficiency -- the essence of the energy model is simple -- all nodes repulse each other -- connected nodes attract each other -- this works for any type of graph -- i'm using a weighted directed graph -- in which case the weighs influence the attractive force It's all very continuous/natural -- living in a 3d world we've build a lot of tools/methods to process this kind of information The problem is without efficiency methods like Barnes-Hut we have Cartesian(x,y) or Cartesian(x,y,z) -- because every vertex influences every other vertex An efficient giraph implementation would need 2 layers -- a bipartite graph -- assuming (x,y,z) reduction -- we would need an Octree graph interacting dynamically w/ our graph of interest On Wed, Mar 7, 2012 at 5:00 AM, Claudio Martella <claudio.marte...@gmail.com> wrote: > My personal take is that they do have similar function (they "extract" > communities), but they have a general different type of output. in > label propagation you'd end up with an id for each vertex (the vertex > id that is the centroid for the community each vertex belongs to), > while i'd expect from linlog something like an (x,y) coordinate. is > that correct? > > On Wed, Mar 7, 2012 at 2:45 AM, Timmy Wilson <tim...@smarttypes.org> wrote: >> Thank you everyone! >> >> I would love to see a comparison of force directed layouts >> (specifically LinLog) and label propagation. >> >> I searched but alas nothing -- they seem to be oddly similar? >> >> The current, serial LinLog implementation -- >> http://code.google.com/p/linloglayout/ -- uses Barnes-Hut simulation >> -- n*log(n): >> >> http://en.wikipedia.org/wiki/Barnes%E2%80%93Hut_simulation >> >> I guess the root question is -- do you think it's reasonable to use >> giraph for Barnes-Hut simulation? >> >> >> >> >> On Tue, Mar 6, 2012 at 11:34 AM, Claudio Martella >> <claudio.marte...@gmail.com> wrote: >>> Hi, >>> >>> I'm not definitely familiar with the algorithm or implementation of >>> LinLog, I've been just a user. It should be doable with Giraph if you >>> can express it in terms of message-passing between vertices and >>> without a dependency on a global view of the graph (except for the >>> convergence criteria, such as total energy). >>> >>> Please consider that Giraph's data model is based on a directed graph, >>> this should be a quite "interesting" constraint for you, if your >>> implementation is going to modify energy associated with edges (you'd >>> have two views over the undirected edge, one in each endpoint). >>> >>> In general, a good way of doing community analysis would be to look at >>> algorithms that belong to the family of label-propagation clustering >>> algorithms. >>> >>> >>> Hope this helps, >>> Claudio >>> >>> On Tue, Mar 6, 2012 at 3:28 PM, Timmy Wilson <tim...@smarttypes.org> wrote: >>>> Hi giraph community, >>>> >>>> I'm interested in using giraph for distributed n-body simulation. >>>> >>>> Initially, i'm interested in force directed layouts -- ie, graph drawing: >>>> >>>> http://en.wikipedia.org/wiki/Force-based_algorithms_(graph_drawing) >>>> >>>> I'm interested specifically in Dr. Andreas Noack's LinLog energy model >>>> -- which performs well w/ community detection: >>>> >>>> http://www.informatik.tu-cottbus.de/~an/GD/linlog.html >>>> >>>> I have a few examples of a serial implementation here: >>>> >>>> http://www.smarttypes.org/ >>>> >>>> The model maximizes the distance between all nodes while minimizing >>>> the distance between connected nodes. >>>> >>>> Without getting into too much detail, i'm curious if anyone has >>>> considered using giraph for force directed graph embedding (yet >>>> another name for it)? >>>> >>>> I'm also considering something like http://www.mcs.anl.gov/petsc/ or >>>> http://www.cs.cmu.edu/~scandal/alg/nbody.html -- which have fast >>>> n-body simulation implementations (Barnes-Hut + Fast Multipole). >>>> >>>> That said, i think giraph may be a good fit -- curious what the >>>> community thinks? >>>> >>>> >>>> Thanks, >>>> Timmy Wilson >>>> Cleveland, OH >>> >>> >>> >>> -- >>> Claudio Martella >>> claudio.marte...@gmail.com > > > > -- > Claudio Martella > claudio.marte...@gmail.com