Exporting visit data to a single file

[sudarshanphy]

I am trying to export visit data for further analysis in python. As per the user guide, I used the xmdv file format to get the coordinates and the field values, but doing that gives me close to 1000 files, each containing some subset of the domain. Is it possible to extract all the data into a single file?

For context, I have a 3D spherical simulation and I want to obtain data on a certain plane. I obtained the normal to the plane, did the slicing, and projected it to 2D. I want to extract this 2D data (on the plane) into a single file for further analysis.

[cyrush]

@sudarshanphy I recommend doing a Blueprint export with the Flatten_CSV option.

This will create two files, one with any element associated variables and one with any vertex associated variables.

ls my_export.csv/
element_data.csv  vertex_data.csv

[sudarshanphy]

@cyrush Thanks. This works for my purpose.

[cyrush]

Great,thanks for letting us know that helped!

[sudarshanphy]

@cyrush Since I am using Visit python scripting for most of my stuff, how can I export the planar dataset? I have successfully used python scripting to export (SaveWindowAtts.format) the to STL files for visualization. However, I am not sure how to export the data to the recommended format (Blueprint). Is it the same process?

[cyrush]

The default case\ for Blueprint (if you don't use Flatten_CSV), will create HDF5 files that include the full geometry and field info in a tree structure. These files can be opened back up in VisIt, or they can be processed in python with tools like h5py, or conduit.

If you want some examples of how to explore Blueprint files in python, here are good docs for our X Ray Image Query:

https://visit-sphinx-github-user-manual.readthedocs.io/en/develop/using_visit/Quantitative/XRayImageQuery.html#introspecting-with-python

If you use Partition target number of domains = 1, VisIt will attempt to connect all the domains and cells together into one topology.

This sewing things together may not work if your projection creates a lot of overlapping geometry, but it is worth trying.

[sudarshanphy]

Thanks!
The following commands worked for me:

e = ExportDBAttributes()
e.db_type   = "Blueprint"
e.filename  = "exported_data"
e.dirname   = "."               
e.variables = ("dens", "eint")
opts = GetExportOptions("Blueprint")
opts["Operation"] = "Flatten_HDF5"
ExportDatabase(e, opts)

I had a single hdf5 file with the projected data.