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/* This is part of the netCDF package.
Copyright 2006 University Corporation for Atmospheric Research/Unidata.
See COPYRIGHT file for conditions of use.
This is an example which reads some surface pressure and
temperatures. The data file read by this program is produced
companion program sfc_pres_temp_wr.cxx. It is intended to
illustrate the use of the netCDF C++ API.
This program is part of the netCDF tutorial:
http://www.unidata.ucar.edu/software/netcdf/docs/netcdf-tutorial
Full documentation of the netCDF C++ API can be found at:
http://www.unidata.ucar.edu/software/netcdf/docs/netcdf-cxx
$Id: sfc_pres_temp_rd.cpp,v 1.6 2010/02/11 22:36:42 russ Exp $
*/
#include <iostream>
#include <string>
#include <netcdf>
using namespace std;
using namespace netCDF;
using namespace netCDF::exceptions;
// We are reading 2D data, a 6 x 12 lat-lon grid.
static const int NLAT = 6;
static const int NLON = 12;
// These are used to calculate the values we expect to find.
static const float SAMPLE_PRESSURE = 900;
static const float SAMPLE_TEMP = 9.0;
static const float START_LAT = 25.0;
static const float START_LON = -125.0;
// Return this code to the OS in case of failure.
static const int NC_ERR = 2;
int main(void)
{
// These will hold our pressure and temperature data.
float presIn[NLAT][NLON];
float tempIn[NLAT][NLON];
// These will hold our latitudes and longitudes.
float latsIn[NLAT];
float lonsIn[NLON];
try
{
// Open the file and check to make sure it's valid.
NcFile dataFile("sfc_pres_temp.nc", NcFile::read);
// There are a number of inquiry functions in netCDF which can be
// used to learn about an unknown netCDF file. In this case we know
// that there are 2 netCDF dimensions, 4 netCDF variables, no
// global attributes, and no unlimited dimension.
//cout<<"there are "<<dataFile.getVarCount()<<" variables"<<endl;
//cout<<"there are "<<dataFile.getAttCount()<<" attributes"<<endl;
//cout<<"there are "<<dataFile.getDimCount()<<" dimensions"<<endl;
//cout<<"there are "<<dataFile.getGroupCount()<<" groups"<<endl;
//cout<<"there are "<<dataFile.getTypeCount()<<" types"<<endl;
// Get the latitude and longitude coordinate variables and read data
NcVar latVar, lonVar;
latVar = dataFile.getVar("latitude");
if(latVar.isNull()) return NC_ERR;
lonVar = dataFile.getVar("longitude");
if(lonVar.isNull()) return NC_ERR;
latVar.getVar(latsIn);
lonVar.getVar(lonsIn);
// Check the coordinate variable data.
for(int lat = 0; lat < NLAT; lat++)
if (latsIn[lat] != START_LAT + 5. * lat)
return NC_ERR;
// Check longitude values.
for (int lon = 0; lon < NLON; lon++)
if (lonsIn[lon] != START_LON + 5. * lon)
return NC_ERR;
// Read in presure and temperature variables and read data
NcVar presVar, tempVar;
presVar = dataFile.getVar("pressure");
if(presVar.isNull()) return NC_ERR;
tempVar = dataFile.getVar("temperature");
if(tempVar.isNull()) return NC_ERR;
presVar.getVar(presIn);
tempVar.getVar(tempIn);
// Check the data.
for (int lat = 0; lat < NLAT; lat++)
for (int lon = 0; lon < NLON; lon++)
if (presIn[lat][lon] != SAMPLE_PRESSURE + (lon * NLAT + lat)
|| tempIn[lat][lon] != SAMPLE_TEMP + .25 * (lon * NLAT + lat))
return NC_ERR;
// Each of the netCDF variables has a "units" attribute. Let's read
// them and check them.
NcVarAtt att;
string units;
att = latVar.getAtt("units");
if(att.isNull()) return NC_ERR;
att.getValues(units);
if (units != "degrees_north")
{
cout<<"getValue returned "<<units<<endl;
return NC_ERR;
}
att = lonVar.getAtt("units");
if(att.isNull()) return NC_ERR;
att.getValues(units);
if (units != "degrees_east")
{
cout<<"getValue returned "<<units<<endl;
return NC_ERR;
}
att = presVar.getAtt("units");
if(att.isNull()) return NC_ERR;
att.getValues(units);
if (units != "hPa")
{
cout<<"getValue returned "<<units<<endl;
return NC_ERR;
}
att = tempVar.getAtt("units");
if(att.isNull()) return NC_ERR;
att.getValues(units);
if (units != "celsius")
{
cout<<"getValue returned "<<units<<endl;
return NC_ERR;
}
// The file will be automatically closed by the destructor. This
// frees up any internal netCDF resources associated with the file,
// and flushes any buffers.
//cout << "*** SUCCESS reading example file sfc_pres_temp.nc!" << endl;
return 0;
}
catch(NcException e)
{
e.what();
cout<<"FAILURE********************************8"<<endl;
return NC_ERR;
}
}
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