Thanks for the reply, but its really easy for us to do the transpose in memory. -Isaac
On Sat, Apr 29, 2017 at 6:20 PM, Wei-keng Liao <[email protected] > wrote: > > In NetCDF/PnetCDF, there is an API family named varm that can achieve such > effect. > > APIs nc_put_varm_int/ncmpi_put_varm_int allows users to writes a mapped > array section of values. The argument imap can be used to describe the > "transpose" > layout of the write buffer. See their API references in > http://cucis.ece.northwestern.edu/projects/PnetCDF/doc/ > pnetcdf-c/ncmpi_005fput_005fvarm_005f_003ctype_003e.html > http://www.unidata.ucar.edu/software/netcdf/docs/group__variables.html# > ga3ff88687cfc7b58293a1cc883780b453 > > In PnetCDF internal implementation, the write buffer is first transposed > to a temporary > buffer which is then written to file. The in-memory 2D transpose is done > by first > creating an MPI derived datatype based on the imap argument, followed by a > call to > MPI_Pack to "pack" the write buffer to the temporary buffer. > > So, the only subroutine an HDF5 user program needs is that in-memory > transpose. > I can extract such subroutine from PnetCDF, but it will be using MPI. Let > me know. > > If you are interested in the PnetCDF case, an example C program is > available in > http://trac.mcs.anl.gov/projects/parallel-netcdf/browser/trunk/examples/C/ > transpose.c > and a short description in > http://trac.mcs.anl.gov/projects/parallel-netcdf/ > browser/trunk/examples/README > > > Wei-keng > > > A coworker and I are mulling over if its possible to take a simple 3x3 > > matrix (stored row major) in a dataspace and write it out transposed to > > disk using a hyperslab. It seems that the grammer provided by start, > > stride, blocks, and count won't allow for this. We hope we are wrong! > It > > is possible to do this? > > > > Thanks, > > Isaac > > > _______________________________________________ > Hdf-forum is for HDF software users discussion. > [email protected] > http://lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org > Twitter: https://twitter.com/hdf5 >
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