Hi, Matthieu, You could use FastBit to do what you would like, but it will take some work.
- FastBit does not require you to explicitly generate x, y, and z, but it does want you to put temperature in a file of its own named temperature. It is possible to keep temperature in your own data file if it is in HDF5, netCDF, or ADIOS BP format <http://www.mcs.anl.gov/events/workshops/iasds11/papers/PID2005987.pdf> - once you have the data file temperature, you need to tell FastBit that the data values are on a regular mesh. This is done with a key-value pair in the header portion of the metadata file -part.txt. Here is an example meshShape = (100, 100, 100) - you can issue queries of type ibis::meshQuery on the data partitions with mesh shape defined. You can find more information about the meshQuery class at <http://lbl.gov/~kwu/fastbit/doc/html/classibis_1_1meshQuery.html>. As you might guessed from the first item mentioned above, we are working on something else to make your task a little easier. Unfortunately, we have not got the official permission to release the source code yet. We are happy to get a few beta testers or collaborators if you are interested. John On 11/17/11 3:13 AM, Matthieu Dorier wrote: > Hello, > > I'm new to FastBit and I have troubles understanding how to use its > C++ API. I would like to do the following: > I have a 3D array of floats representing a physical value (for > instance "temperature") along a 3D grid. > I would like to be able to answer queries like "give me all the > coordinates (x,y,z) where temperature > T", without having to > transform the original data into a list of (x,y,z,temperature) tuples, > without making a copy of these data, without writing anything to a > file (the resulting index could eventually be stored in a file, but I > don't want it to be done automatically). In other words, I would like > to simply wrap my data (along with other information if required) into > a structure from which FastBit can work. > How can I do that? > > Thanks > > -- > Matthieu Dorier > ENS Cachan, Brittany (Computer Science dpt.) > IRISA Rennes, Office E324 > http://perso.eleves.bretagne.ens-cachan.fr/~mdori307/wiki/ > <http://perso.eleves.bretagne.ens-cachan.fr/%7Emdori307/wiki/> > > > _______________________________________________ > FastBit-users mailing list > [email protected] > https://hpcrdm.lbl.gov/cgi-bin/mailman/listinfo/fastbit-users _______________________________________________ FastBit-users mailing list [email protected] https://hpcrdm.lbl.gov/cgi-bin/mailman/listinfo/fastbit-users
