netcdf-perl examples

#!/usr/local/bin/perl

# Example program to encode variable length strings into a NetCDF file.
# S. Diggs (address@hidden) 1999.11.15

use diagnostics;
#use strict;
use NetCDF;

unlink( "string_example.nc" );

# strings
my @atmospheric_conditions = (  "cloudy", "sunny",
                                "fog",
                                "rain" );

my @count_ac = ($#atmospheric_conditions);

print STDOUT "dimensions of array are @count_ac\n";

#
my $ncid  = NetCDF::create("string_example.nc", NetCDF::WRITE);
#my $dimid = NetCDF::dimdef($ncid, 'recNum', NetCDF::UNLIMITED);
$string_dimension = 80;
my $sD = NetCDF::dimdef($ncid, 'string_dimension', $string_dimension);
#
NetCDF::attput($ncid, NetCDF::GLOBAL, "STRING_EXAMPLE", NetCDF::CHAR,
                        "This is an example of string encoding");

my $varid_ac   = NetCDF::vardef($ncid, 'ATM_COND', NetCDF::CHAR, $sD);
;

# leaving define mode
NetCDF::endef($ncid);

#NetCDF::close($ncid);

#exit(0);

print STDERR "Leaving define mode....\n";

#put data into netcdf file

my $i=0;
my @start = (0);
my @new_count = (80);   
$S80 = "\0" x $string_dimension ;

foreach my $element (@atmospheric_conditions)   {

        #@new_count = (length($element));
        #print STDERR " Variable $i length = @new_count\n\t",
        #               "starting at @start\n\n";
        $element = padstr( $element, $string_dimension);
        NetCDF::varput($ncid, $varid_ac, \@start, \@new_count, 
                \$element);
        $i++;
        #bump the new starting point by adding the old ending point
        # to where we are now
        #@start = (($new_count[0] + $start[0]));
        last;
}

NetCDF::close($ncid);
#done!

# code to demonstrate UNLIMITED records

$cdlfile = "sd.cdl" ;
$ncfile = "sd.nc" ;
$ncgen = "/upc/netcdf/bin/ncgen" ;
system( "$ncgen -o $ncfile $cdlfile" ) ;
$ncid = NetCDF::open( "$ncfile", WRITE ) ; 
$S80 = "\0" x $string_dimension ;
$ii = 0;

foreach my $element (@atmospheric_conditions)   {

        $element = padstr( $element, $string_dimension);
        @dataref = ( \$element );
        #$results = NetCDF::recput($ncid, $ii, [@dataref]);
        $results = NetCDF::recput($ncid, $ii, [(\$element)]);
        print "$results\n" if( $results );
        $ii++;
}

@dataref = ( \$S80 );

for( $record = 0; $record <= 3; $record++ ) {
        $results = NetCDF::recget( $ncid, $record,  \@dataref );
        print "$results\n" if( $results );
        $ac = ${$dataref[ 0 ]} ;
        print "record = $record , $ac\n" ;
}
NetCDF::close($ncid);
        
# pad str to correct length
sub padstr
{
( $str, $len ) = @_ ;

my( $size, $i ) ;

$size = length( $str ) ;

for( $i = $size; $i < $len; $i++ ) {
        $str .= "\0" ;
        #print "$str,\n" ;
}
if( $size > $len ) {
        print STDOUT "String length is over $len chars long:\n $str\n" ;
        $str = substr( $str, 0, $len ) ;
        #exit 0 ;
}
return $str ;
}


netcdf string_example {
dimensions:
        recNum = UNLIMITED ; // (0 currently)
        string_dimension = 80 ;
variables:
        char ATM_COND(recNum, string_dimension) ;

// global attributes:
                :STRING_EXAMPLE = "This is an example of string encoding" ;
}
===============================================================================
Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
address@hidden             WWW: http://www.unidata.ucar.edu/
===============================================================================