On Tue, Sep 16, 2003 at 11:20:13AM -0400, Jason Thaxter wrote:
> I've found two odd problems with NetCDF tools recently. I suspect they are
> related to compiler and perl versions, but I don't really know.
>
> 1) ----------------------------------------------------
>
> The Perl interface issue involves values retrieved by NetCDF::recget. The
> variable is a scalar of type BYTE. Perl always thinks it has a zero (0), even
I figured out this particular problem; the perl-netcdf library does not appear
to be misbehaving at all, though it does things that might trap an unwary -
and at least in this case, fairly wary - perl programmer.
Variables of the NetCDF::BYTE type cannot be immediately used as perl
variables. They will end up looking like "^A" or "^@" or something else when
you try to use them as strings; worse, if you look at them as numbers, they
will always appear to be zero.
Suppose that $value is an actual single value retrieved from
attget/varget/recget. To use a NetCDF::BYTE properly, do this
$value = unpack('C',$value);
I put this trick into a wrapper module I've written around NetCDF, called
GoMOOS::NetCDF. There are a number of other tricks there, too - initializing
arrays before passing them to NetCDF functions, retrieving variables by names
instead of index number, etc. I wouldn't say it's complete or flawless; it's
a little inconsistent about return values, and it's probably more useful for
taking a record-oriented view than a variable-oriented view, and it's totally
useless for writing NetCDF files.
Nevertheless, anyone using perl-netcdf may find it useful and so I've
attached it to this message. If the attachment doesn't make it through
majordomo onto the list, feel free to e-mail me for a copy.
Thanks,
Jason
--
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Jason Thaxter
GoMOOS, P.O. Box 4919, Portland, ME 04112-4919
Office Location: 1 Canal Plaza, 7th Floor
Office: 207.773.0423
Fax: 207.773.8672
Email: thaxter@xxxxxxxxxx
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Description: Perl program
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