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Re: nCDF_Browser Updated to Support HDF Files [message #65281]

Wed, 25 February 2009 07:32

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

James Kuyper writes:

> Within the context of HDF, "scientific dataset" refers to a particular
> kind of data that you can store in an HDF file. A scientific data set is
> a multi-dimensional named array of a single specific data type, to which
> can be attached a number of named attributes, each of which can be a
> one-dimensional array of a specific data type.
>
> Other things you can store in an HDF file include vdatas (essentially
> 1-dimension arrays of a structure type with a fixed layout; the vdata
> fields can be a mixture of different data types), vgroups, and images in
> 8-bit, 24-bit, and general raster formats, palettes, and annotations.

Thank you, James, for expanding on this topic. (I was getting
ready for work and only had time to be flippant.)

I would point out, too, that sorting out what is inside
an HDF file when you don't know much about it (the usual
case, I think), is not a trivial task. Presumably the
HDF_BROWSER code that comes with IDL can do it, but that
code isn't exposed to us mortals, so we can't see how it
is done. Reading the documentation, which is just about
the only alternative available to us, is a fool's errand.

Generally speaking, if you want to decipher what is in
an HDF file you scrounge around the Internet until you
find a scrap of code (usually written for IDL 5.2) that
does *almost* what you want it to do and you then beat it
into shape with whatever blunt instruments you have at your
disposal.

I've grown tired of doing this, so I've started to write my
own code for these kinds of things. But, it is a painful,
painful process, I can tell you.

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: nCDF_Browser Updated to Support HDF Files By: David Fanning on Wed, 25 February 2009 07:32
		Re: nCDF_Browser Updated to Support HDF Files By: jameskuyper on Wed, 25 February 2009 07:14
		Re: nCDF_Browser Updated to Support HDF Files By: David Fanning on Wed, 25 February 2009 06:36
		Re: nCDF_Browser Updated to Support HDF Files By: Brian Larsen on Wed, 25 February 2009 06:34
		Re: nCDF_Browser Updated to Support HDF Files By: David Fanning on Mon, 23 February 2009 18:06
		Re: nCDF_Browser Updated to Support HDF Files By: Brian Larsen on Mon, 23 February 2009 07:49
		Re: nCDF_Browser Updated to Support HDF Files By: Kenneth P. Bowman on Thu, 26 February 2009 10:46

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