#!/usr/bin/env perl
use strict;
# ==========================================================================
# Example script for reading NetCDF files through OPeNDAP with Perl
# ==========================================================================
#
# This script shows some examples of how to read a NetCDF file in Perl.
# It makes use of the Perl module PDL::NetCDF, a perl-netCDF interface
# based on the use of "piddles" (PDL).
# In order to be able to use this script, you need:
# - a Perl installation
# - the PDL module of Perl
# (re. http://cpansearch.perl.org/src/CSOE/PDL-2.4.3/INSTALL)
# - NetCDF installation with OPeNDAP support
# (re. http://www.unidata.ucar.edu/software/netcdf/index.html)
# - the installation of the PDL::NetCDF module
# (re. http://search.cpan.org/~dhunt/PDL-NetCDF-4.03/)
#
# ==========================================================================
# --------------------------------------------------------------------------
# Use PDL::NetCDF to read NetCDF files in Perl
# --------------------------------------------------------------------------
use PDL;
use PDL::NetCDF;
#
# --------------------------------------------------------------------------
# Open a remote NetCDF file ($nc will contain the NetCDF file object)
# Remark 1: the file "201007050850.nc" may have been cleaned up. Consult the
# URL below to get a valid file name
# Remark 2: instead of a remote NetCDF file you may specify a local file
# --------------------------------------------------------------------------
my $url = 'http://www.institution.nl/matroos/partners/opendap/cgi-bin/nph-dods/matroos/data/normal/hmcn_csm8';
my $ncfile = "$url/201007050850.nc";
my $nc = PDL::NetCDF->new($ncfile);
#
# --------------------------------------------------------------------------
# Get the list of variables in the NetCDF file (object $nc)
# --------------------------------------------------------------------------
my $varlist = $nc->getvariablenames();
print "Variables on this file: \n @{$varlist}\n";
print "\n";
# --------------------------------------------------------------------------
# Read the time array
# --------------------------------------------------------------------------
my $time = $nc->get('time');
print "Time array:\n $time\n";
print "\n";
# --------------------------------------------------------------------------
# Get the attributes of the time array
# --------------------------------------------------------------------------
my $attlist = $nc->getattributenames('time');
print "Time array attributes:\n";
foreach my $attname ( @{$attlist} ) {
my $attr = $nc->getatt($attname,'time');
print " $attname: $attr\n";
}
print "\n";
# --------------------------------------------------------------------------
# Get dimensions of the water level array SEP
# --------------------------------------------------------------------------
my $dims = $nc->getdimensionnames('SEP');
print "Dimension names of SEP:\n @{$dims}\n";
print "\n";
# --------------------------------------------------------------------------
# Get the attributes of the SEP array
# --------------------------------------------------------------------------
my $attlist = $nc->getattributenames('SEP');
print "SEP array attributes:\n";
foreach my $attname ( @{$attlist} ) {
my $attr = $nc->getatt($attname,'SEP');
print " $attname: $attr\n";
}
print "\n";
# --------------------------------------------------------------------------
# Read a slice of the water level array SEP
# --------------------------------------------------------------------------
# [0,0,0] is starting point, [1,1,5] is the count
my $slice = $nc->get('SEP',[0,0,0],[1,1,5]);
print "First slice:\n $slice\n";
print "\n";
# Read another slice, 2nd timestep = starting point [1,0,0]
my $slice = $nc->get('SEP',[1,0,0],[1,1,5]);
print "Second slice:\n $slice\n";
print "\n";
# --------------------------------------------------------------------------
# Close the NetCDF file
# --------------------------------------------------------------------------
$nc->close;
|
#!/usr/bin/env perl
use strict;
# ==========================================================================
# Example script for creating a NetCDF file
# ==========================================================================
#
# This script shows an example of how to write a NetCDF file in Perl.
# It makes use of the Perl module PDL::NetCDF, a perl-netCDF interface
# based on the use of "piddles" (PDL).
# In order to be able to use this script, you need:
# - a Perl installation
# - the PDL module of Perl
# (re. http://cpansearch.perl.org/src/CSOE/PDL-2.4.3/INSTALL)
# - NetCDF installation (with OPeNDAP support)
# (re. http://www.unidata.ucar.edu/software/netcdf/index.html)
# - the installation of the PDL::NetCDF module
# (re. http://search.cpan.org/~dhunt/PDL-NetCDF-4.03/)
#
# ==========================================================================
# --------------------------------------------------------------------------
# Use PDL::NetCDF to write NetCDF files in Perl
# --------------------------------------------------------------------------
use PDL;
use PDL::Char;
use PDL::NetCDF;
#
# Time::localtime for nice time functions
use Time::localtime;
#
# --------------------------------------------------------------------------
# Open a new NetCDF file ($nc will contain the NetCDF file object)
# --------------------------------------------------------------------------
my $ncfile = "MyNetCDF.nc";
unlink $ncfile if ( -f $ncfile);
my $nc = PDL::NetCDF->new($ncfile);
# --------------------------------------------------------------------------
# Add some global attributes to this NetCDF
# --------------------------------------------------------------------------
my $tm = localtime;
my $today = sprintf("%04d-%02d-%02d", $tm->year+1900, ($tm->mon)+1,
$tm->mday);
$nc->putatt ('Global attribute', 'global_attr');
$nc->putatt ($today , 'creation_date');
#
# --------------------------------------------------------------------------
# Create a "piddle" to write
# --------------------------------------------------------------------------
my $pdl = pdl [[1, 2, 3], [4, 5, 6]];
# --------------------------------------------------------------------------
# Write this piddle to our new NetCDF
# --------------------------------------------------------------------------
# Specify variable name to put PDL in, plus names of the dimensions.
# Dimension lengths are taken from the PDL, in this case, dim1 = 2 and
# dim2 = 3.
$nc->put ('SomeVariable', ['dim1', 'dim2'], $pdl);
# --------------------------------------------------------------------------
# Add some attributes to this array
# --------------------------------------------------------------------------
$nc->putatt ('My first attribute', 'attr_name_1', 'SomeVariable');
$nc->putatt ('Another attribute' , 'attr_name_2', 'SomeVariable');
$nc->putatt (double([1,2,3]) , 'double_attr', 'SomeVariable');
# --------------------------------------------------------------------------
# Create and add a character array to the NetCDF file
# --------------------------------------------------------------------------
my $str = PDL::Char->new (['Station1', 'Station2', 'Station3']);
$nc->put ('stations', ['dim_station', 'dim_charlen'], $str);
# --------------------------------------------------------------------------
# And add some attributes to this string array
# --------------------------------------------------------------------------
$nc->putatt ('String attribute', 'string_attr_name', 'stations');
# --------------------------------------------------------------------------
# Close the NetCDF file
# --------------------------------------------------------------------------
$nc->close;
# --------------------------------------------------------------------------
# Now you can inspect what has been created using "ncdump"
# --------------------------------------------------------------------------
print "\n" .
"=================\n" .
"Output of ncdump:\n" .
"=================\n" .
"\n";
system ("ncdump $ncfile");
|
Code provided by Regien Brouwer of the MATROOS operational storm surge database.