A few quick netCDF questions

• To: chouck@xxxxxxxxxxxxx
• Subject: A few quick netCDF questions
• From: Russ Rew <russ@xxxxxxxxxxxxxxxx>
• Date: Tue, 9 Jun 1992 13:32:47 -0600

Chris,

> 1)  The netCDF manual doesn't explicitly forbid it, but from the
>       code it looks impossible for a string valued attribute
>       to have more than one value, i.e. in CDL:
> 
>       my_var:greetings    = "hello", "goodbye";
> 
>       Am I correct that this is not allowed?

You can do this in CDL, but it just concatenates the strings into a single
array of characters.  Since any attribute is just a one-dimensional array of
values of some type, the result is an attribute of characters of length
large enough to hold the string "hellogoodbye".  There is really no such
thing as a "string-valued" attribute, since "string" is not one of the
primitive netCDF types.  However multi-valued attributes of character type
are not very different from string-valued attributes, in that they are an
array of characters with a length.  If you want to adopt a convention that
"," separates strings, for example, then the attribute "one,two,three" could
be thought of as a string-valued attribute containing three strings, but
that's purely convention.  The netCDF library treats it as a single attribute
of 14 characters.

> 2)  We have been building off of netCDF 2.02 on your ftp 
>       server.  Have there been any bug fixes / modifications
>       since then that we should be aware of?

Glenn described a significant optimization for netCDF on UNIX that we
haven't decided how to package yet.

There was a minor change to ncdump and ncgen to permit the netCDF names in a
CDL file to begin with a non-alphabetic character, and thus to permit ncgen
to work for files generated by ncdump from filenames that begin with a
non-alphabetic character.

There have been some clarifications and fixes to the documentation and the
installation instructions and a minor bug fix to the FORTRAN interface.

I don't think you need to be concerned with any of these changes for your
release.

--Russ

• References:
  • A few quick netCDF questions
    • From: chouck