Miscellany

package lab10;

import java.awt.Color;
import java.util.Scanner;
import java.io.*;

import edu.mines.jtk.dsp.Sampling; // see documentation online
import edu.mines.jtk.mosaic.*;

/**
 * Convenient class for tiltmeter data; for internal use only (not public).
 */
class TiltData
{
	Sampling t; // uniform time sampling, in hours since 2004.09.01
	float[] x;  // measured tilts, in nrad (nanoradians!)
	TiltData(Sampling t, float[] x) 
	{
		this.t = t;
		this.x = x;
	}
}

/**
 * Reads and writes tiltmeter data.
 * Data were extracted from Matlab files provided by 
 * Professor Hartmut Spetzler, University of Colorado.
 * <pre>
 * Text file format: 
 * line 1: number of samples
 * line 2: time sampling interval, in hours since 2004.09.01
 * line 3: time of first sample, in hours since 2004.09.01
 * all remaining lines contain tilts, in nanoradians
 * </pre>
 * <pre>
 * Binary file format: 
 * int: number of samples
 * float: time sampling interval, in hours since 2004.09.01
 * float: time of first sample, in hours since 2004.09.01
 * all remaining floats contain tilts, in nanoradians
 * </pre>
 */
public class TiltMeter 
{
	/**
	 * Main program. (No args required.)
	 */
	public static void main(String[] args)
	{
		TiltData td;

		// Text file I/O; when done, tilt.txt and tilt2.txt should be identical.
		td = readText("src/lab10/tilt.txt");
		plot(td);
		writeText(td,"src/lab10/tilt2.txt");
		td = readText("src/lab10/tilt2.txt");
		plot(td);

		// Binary file I/O; when done, tilt.dat and tilt2.dat should be identical.
		td = readBinary("src/lab10/tilt.dat");
		plot(td);
		writeBinary(td,"src/lab10/tilt2.dat");
		td = readBinary("src/lab10/tilt2.dat");
		plot(td);

		// Some useful processing.
		plot(td, despike(td));
	}

	/**
	 * Reads tiltmeter data from text file.
	 * @param fileName name of text file.
	 * @return tiltmeter data; null, if I/O exception is thrown.
	 */
	static TiltData readText(String fileName)
	{
		FileInputStream fis = null;
		
		try
		{
			fis = new FileInputStream(fileName);
			
		} catch (IOException e) 
		{
			System.out.println(e);
			System.exit(0);
		}
		
		Scanner s = new Scanner(fis);
	
		int n = s.nextInt();
		float interval = s.nextFloat();
		float initial = s.nextFloat();
		
		float[] f = new float[n];
		
		for (int i = 0; i < n; i++)
		{
			f[i] = s.nextFloat();
		}
		
		s.close();
		
		return new TiltData(new Sampling(n, interval, initial), f);
	}

	/**
	 * Writes tiltmeter data to text file.
	 * @param td tiltmeter data.
	 * @param fileName name of text file.
	 */
	static void writeText(TiltData td, String fileName)
	{	
		try
		{
			FileOutputStream fos = new FileOutputStream(fileName);
			PrintWriter pw = new PrintWriter(fos);
			
			int n = td.t.getCount();
			float interval = (float)td.t.getDelta();
			float initial = (float)td.t.getFirst();		
			
			pw.println(n);
			pw.println(interval);
			pw.println(initial);
			
			for (int i = 0; i < n; i++)
			{
				pw.println(td.x[i]);
			}
			pw.close();
		} 
		catch (IOException e)
		{
			System.out.println(e);
		}
	}

	/**
	 * Reads tiltmeter data from binary file.
	 * @param fileName name of binary file.
	 * @return tiltmeter data; null, if I/O exception is thrown.
	 */
	static TiltData readBinary(String fileName)
	{
		try
		{	
			FileInputStream fis = new FileInputStream(fileName);
			DataInputStream dis = new DataInputStream(fis);
		
			int n = dis.readInt();
			float interval = dis.readFloat();
			float initial = dis.readFloat();
			
			float[] f = new float[n];
			
			for (int i = 0; i < n; i++)
			{
				f[i] = dis.readFloat();
			}
			
			dis.close();
			
			return new TiltData(new Sampling(n, interval, initial), f);	
		} 
		catch (IOException e) 
		{
			System.out.println(e);
		}
		
		return null;
	}

	/**
	 * Writes tiltmeter data to binary file.
	 * @param td tiltmeter data.
	 * @param fileName name of binary file.
	 */
	static void writeBinary(TiltData td, String fileName)
	{
		try 
		{
			FileOutputStream fos = new FileOutputStream(fileName);
			DataOutputStream dos = new DataOutputStream(fos);
			
			int n = td.t.getCount();
			float interval = (float)td.t.getDelta();
			float initial = (float)td.t.getFirst();
			
			dos.writeInt(n);
			dos.writeFloat(interval);
			dos.writeFloat(initial);
			
			for (int i = 0; i < n; i++)
			{
				dos.writeFloat(td.x[i]);
			}
			
			dos.close();
			
		} catch (IOException e)
		{
			System.out.println(e);
		}
	}

	/**
	 * Removes noise spikes from tiltmeter data.
	 * For all except the first and last samples, output values equal
	 * the median of the three nearest input samples.
	 * @param td input tiltmeter data; not modified
	 * @return output despiked tiltmeter data
	 */
	static TiltData despike(TiltData td)
	{
		float[] f = td.x;
		int n = td.t.getCount();
		
		Sampling sampling = td.t;
		
		float[] d = new float[n];
		
		for (int i = 0; i < n; i++)
		{
			if (i == 0) // first sample
			{
				d[0] = f[0];
			}
			else
			{
				if (i == n-1) //last sample
				{
					d[n-1] = f[n-1];
				}
				else
				{
					float before = f[i-1];
					float current = f[i];
					float after = f[i+1];
					
					if ((before <= current && before >= after) || (before >= current && before <= after))
						d[i] = before;
					else if ((current <= before && current >= after) || (current >= before && current <= after))
						d[i] = current;
					else 
						d[i] = after;
				}
			}
		}
		
		return new TiltData(sampling, d);		
	}

	/**
	 * Plots tiltmeter data.
	 * @param td tiltmeter data
	 */
	static void plot(TiltData td) 
	{
		SimplePlot sp = SimplePlot.asPoints(td.t,td.x);
		sp.setTitle("Tiltmeter data");
		sp.setHLabel("time (hours)");
		sp.setVLabel("tilt (nrad)");
	}

	/**
	 * Plots two sequences of tiltmeter data.
	 * @param td1 tiltmeter data
	 * @param td2 tiltmeter data
	 */
	static void plot(TiltData td1, TiltData td2) 
	{
		SimplePlot sp = new SimplePlot();
		PointsView pv1 = sp.addPoints(td1.t,td1.x);
		pv1.setLineColor(Color.RED);
		PointsView pv2 = sp.addPoints(td2.t,td2.x);
		pv2.setLineColor(Color.BLUE);
		sp.setTitle("Tiltmeter data");
		sp.setHLabel("time (hours)");
		sp.setVLabel("tilt (nrad)");
	}
}