Re: Fixed problem

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
address@hidden             WWW: http://www.unidata.ucar.edu/
===============================================================================







> 
> > 
> > Steve,
> > 
> > I was extremely busy yesterday so I couldn't remember the syntax for the
> > multidimensional arrarys, etc. I modified the the example you sent, using
> > the 1st dim as unlimited, thats what my understanding was yesterday.
> > The original example is dependent on the manner that perl stores
> > strings in arrays thats why the padstr function is used so one gets
> > what one expects. Sometime the API don't work as expected. Don't
> > ever think I will not answer a question, sometimes I need time to get to
> > the problem.
> > 
> > Robb...
> > 
> 

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

#!/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
address@hidden             WWW: http://www.unidata.ucar.edu/
===============================================================================