Scheller, Robert M. wrote:
Dear John Caron:
I am a grad student at UW-Madison and I have been attempting
to work with a suite of VEMAP climate data files in the
netCDF format. Although the User's Manual for NetCDF Java
has been helpful, I am utterly stuck. It appears fairly
simple to create the NetcdFile class. However, I want only
a very small subsection of the data. It appears that ma2.Index
would provide this function but I haven't been able to
make the logical leap from creating the NetcdFile class to
creating a MultiArray that I can index on. Specifically, it
isn't clear to me how to use the MultiArray read() functions
on a netcdfile.
Hi Rob: you dont directly manipulate Index, the read() is done on the
Variable to get an in-memory Array, see example below.
Also, what is the constructor for the Range
class? Thanks very much for any information, advise or
references you could provide.
see http://www.unidata.ucar.edu/packages/netcdf-java/ and print out the
"user documentation".
there's also online javadoc there, you can look up the Range class
Sincerely,
Rob Scheller
Robert M. Scheller
Dept. Forest Ecology & Management
University of Wisconsin - Madison
1630 Linden Dr., Madison, WI 53706
w: 608.265.6321
Visit my webpage! http://landscape.forest.wisc.edu/staff/rob/
Forest Landscape Ecology Lab http://landscape.forest.wisc.edu
Here's an example that 1) reads a 2x2 subset of an array and then 2)
reads the entire array and subsets it.
package test.nc2;
import ucar.ma2.*;
import ucar.nc2.*;
import java.io.*;
public class ExampleRead {
public static void main(String [] args) {
new ExampleRead();
}
public ExampleRead() {
try {
NetcdfFile ncfile = new
NetcdfFile("E:/metapps/src/test/nc2/mydata.nc");
System.out.println( "ncfile "+ ncfile);
Variable temp = ncfile.findVariable("temperature");
System.out.println( "temperature "+ temp);
// read subset
int[] origin = {1,3};// start at index [1,3]
int[] shape = {2,2}; // 2x2 array
Array As = temp.read( origin, shape);
System.out.println( "physical subset");
printArray( As);
// read all the data and logically subset it
Array A = temp.read();
Range[] r = new Range[2];
r[0] = new Range(1,2);
r[1] = new Range(3,4);
Array Ap = A.section( r); // logical subset
System.out.println( "logical subset");
printArray( Ap);
} catch (InvalidRangeException e) {
System.err.println("ERROR reading file "+e);
return;
} catch (IOException e) {
System.err.println("ERROR reading file "+e);
return;
}
}
private void printArray( Array a) {
IndexIterator iter = a.getIndexIterator();
while (iter.hasNext())
System.out.println( iter.getDoubleNext()+ ",");
}
}
