Re: Fixed problem

• To: Steve Diggs <sdiggs@xxxxxxxxxxxxxx>
• Subject: Re: Fixed problem
• From: Robb Kambic <rkambic@xxxxxxxxxxxxxxxx>
• Date: Mon, 22 Nov 1999 14:24:26 -0700 (MST)

On Sun, 21 Nov 1999, Steve Diggs wrote:

Robb:

OK, now I have another question.  How the heck do I get the multi-dim CHAR
variable back out?

I can't find the proper syntax in the Perl interface to open the NetCDF
file in your example to read in the CHAR data.  Could you extend your
last example to _specifically_ read in the CHAR array you write out?  (as in
close the file then reopen, get info, read CHAR array (all of it at once)
into a Perl array, print array).  I don't think that this would be so
difficult.  A user manual sure would help...

thanks again,
-sd

Steve,

Here's an example of reading a NetCDF file using varget.

Robb...


#!/opt/bin/perl
 use NetCDF ;

 $ncfile = "demo.nc" ;
 $ncid   = NetCDF::create($ncfile, NetCDF::CLOBBER ) ;
 $dimid = NetCDF::dimdef($ncid, 'recNum', NetCDF::UNLIMITED);
 $stadim = NetCDF::dimdef($ncid,"stations",10) ;
 $strlen = 10 ;
 $strdim = NetCDF::dimdef($ncid,"strlen", $strlen) ;
 $varid  = NetCDF::vardef($ncid,"station",NetCDF::CHAR,[$dimid,$strdim]);
 NetCDF::endef($ncid) ;

 @names = ( "abcdef", "ABCDEF","A", "B", "C", "D", "E", "F", "G", "H" ) ;
 for ($i = 0 ; $i < 10 ; $i++ ) {
     $names[ $i ] = padstr( $names[ $i ], $strlen ) ;
     NetCDF::varput( $ncid, $varid, [$i,0], [1, $strlen], \$names[ $i ] ) ;
     #NetCDF::varput( $ncid, $varid, [$i,0], [1,10], "??????????" ) ;
     }


 NetCDF::close($ncid) ;

# Example to reopen file and read the data

$ncid = NetCDF::open( "$ncfile", WRITE ) ;
$station_id = NetCDF::varid( $ncid, "station" ) ;
print "station_id =$station_id\n\n" ;


for ($i = 0 ; $i < 10 ; $i++ ) {
        @aStn = ($strlen  x "\0" ) ;
        NetCDF::varget( $ncid, $station_id, [$i,0], [1, $strlen], \@aStn ) ;

       $newStation = "";
       for ($j = 0; $j < $strlen; $j++) {
           $stnChr = chr($aStn[$j]);
           last if( $stnChr eq "\0" || $stnChr eq "\\" ) ;
           $newStation .= $stnChr ;
       }
        print "Station $i = $newStation\n" ;
}

NetCDF::close($ncid) ;
exit( 0 ) ;

# 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 ;
}
__END__

And this is what I get from ncdump:

ncdump demo.nc
netcdf demo {
dimensions:
       recNum = UNLIMITED ; // (10 currently)
       stations = 10 ;
       strlen = 10 ;
variables:
       char station(recNum, strlen) ;
data:

station
 "abcdef",
 "ABCDEF",
 "A",
 "B",
 "C",
 "D",
 "E",
 "F",
 "G",
 "H" ;

Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
rkambic@xxxxxxxxxxxxxxxx                   WWW: http://www.unidata.ucar.edu/
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