> while i'd expect from linlog something like an (x,y) coordinate. is
> that correct?
(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 BarnesHut 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.martella@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 <timmyt@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 BarnesHut 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 BarnesHut simulation?
>>
>>
>>
>>
>> On Tue, Mar 6, 2012 at 11:34 AM, Claudio Martella
>> <claudio.martella@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 messagepassing 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 labelpropagation clustering
>>> algorithms.
>>>
>>>
>>> Hope this helps,
>>> Claudio
>>>
>>> On Tue, Mar 6, 2012 at 3:28 PM, Timmy Wilson <timmyt@smarttypes.org> wrote:
>>>> Hi giraph community,
>>>>
>>>> I'm interested in using giraph for distributed nbody simulation.
>>>>
>>>> Initially, i'm interested in force directed layouts  ie, graph drawing:
>>>>
>>>> http://en.wikipedia.org/wiki/Forcebased_algorithms_(graph_drawing)
>>>>
>>>> I'm interested specifically in Dr. Andreas Noack's LinLog energy model
>>>>  which performs well w/ community detection:
>>>>
>>>> http://www.informatik.tucottbus.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
>>>> nbody simulation implementations (BarnesHut + 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.martella@gmail.com
>
>
>
> 
> Claudio Martella
> claudio.martella@gmail.com
