package circulardata;

/*  This is the Range Test.
 *
 *  Author: Ivan Ramler, Jake Krohn, and Brian Gluth
 *  Date: 29 April 2002
 */

import java.io.*;

public class RangeTest {
  //calculateRangePValue method
  public double calculateRangePValue(CircularData cd, double r) {
    int obs = cd.getObservations();
	  
    double pvalue = 0; //Probablity of W <= r
        
    //used to calculate upper bound of summation
    double x = (2 * Math.PI) / (2 * Math.PI - r);
        
    //upper bound of summation, largest integer <= x
    int upperbound = (int) Math.floor(x);

    //formula to calculate pvalue
    for (int k = 1; k < upperbound + 1; k++) { 
      pvalue += Math.pow(-1, k - 1)
                * (cd.factorial(obs)
                    / (cd.factorial(k) * cd.factorial(obs - k)))
                * Math.pow((1 - (k * (2 * Math.PI - r) / (2 * Math.PI))), obs - 1);
    }

    return pvalue;
  }

  //findRangeTestStatistic method
  public double findRangeTestStatistic(CircularData cd) {
    int obs = cd.getObservations();	//#observation in data set
    double[] data = cd.getData();	//array 'data' of data points
	  
    double r; //circular range - test statistic in radians
    double w; //circular range - in degrees
    double maxdiff = 0; //maximum difference between adjacent sorted observations

    //find maxdiff between adjacent observations (in a linear sense)
    for (int i = 0; i < obs - 2; i++) {
      if (maxdiff < data[i + 1] - data[i])
        maxdiff = data[i + 1] - data[i];
    }

    //check if difference between last and first observations are larger than current maxdiff
    if (maxdiff < 360 + data[0] - data[obs - 1])
      maxdiff = 360 + data[0] - data[obs - 1];

    w = 360 - maxdiff; //get circular range
    r = (w / 180) * Math.PI; //convert w to radians - Test Statistic
    return r;

  }

  //main method
  public static void main(String[] args) {
    //Prints authors' names and date of creation
    System.out.println("Created by Ivan Ramler, Jake Krohn, and Brian Gluth.");
    System.out.println("April 2002");

    //Declare variables
    double r;    //Circular range in radians - Test Statistic
    double pvalue = 0.0;  //P(W <= r)

    String fileName = args[0];
    File f = new File(fileName);    

    //create objects
    CircularData data1 = new CircularData(f);
    RangeTest rt = new RangeTest();

    //sort data
    data1.selectionSort();
   
    //find r
    r = rt.findRangeTestStatistic(data1);

    //calculate p-value
    pvalue = rt.calculateRangePValue(data1, r);

    //Print test statistic and p-value  
    System.out.println("The Test Statistic for the Range Test is " + r);
    System.out.println("The Test Statistic in degrees is " + r*180/Math.PI);
    System.out.println("The P(W <= " + r + ") = " + pvalue);
  }
}