Re: Export data from SpreadSheet & Re: FileFlatField

• To: "Peter X. Cao" <xcao@xxxxxxxxxxxxx>
• Subject: Re: Export data from SpreadSheet & Re: FileFlatField
• From: "From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>" <billh@xxxxxxxxxxxxx>
• Date: Tue, 21 Dec 1999 15:34:40 -0600 (CST)

Hi Peter,

> I'd like to add a menuitem in the file menu to export
> data to HDF5 file.

This is a nice suprise.  You must be implementing the save()
method in your HDF-5 adapter.  Terrific.

Let me wait on your specific questions about changing the
SpreadSheet until Curtis returns from vacation.  He's the
SpreadSheet expert.

I'd like to add a little more to what I said earlier about
factoring domains of very large FlatFields.  In general, it
will be convenient to users and programmers if adapters
factor domains with more than three dimensions, especially
if one of the dimensions is Time (which users may want to
map to Animation).

However, when domains are three spatial dimensions, then it
is nice to not factor them.  Ideally, an adapter will check
the size of the file and only factor three spatial dimensions
is the resulting FlatField will be too large for memory.
Files with very large spatial samplings won't display very
well in the SpreadSheet anyways (the display code will
probably run out of memory), so it may not be worth worrying
about them in a file adapter intended to be used with the
SpreadSheet.

There may be more than one adapter (i.e., more than one
extension of visad.data.Form) for a given file format.  For
example, there are two for HDF-EOS: one that uses disk
caching and one that reads the entire file into memory.
So for HDF-5 you might consider more than one adapter, one
for small files and one for very large files that is
aggressive in disk caching and factoring field domains.
The two HDF-EOS adapters share a lot of code, and hopefully
multiple HDF-5 adapters could share code also.

Cheers,
Bill
----------------------------------------------------------
Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738
http://www.ssec.wisc.edu/~billh/vis.html

• References:
  • Export data from SpreadSheet
    • From: Peter X. Cao