/*
*
* To generate weather for location at longitude -98.76 and latitude 26.70 for
* the month of February do:
* java WeatherGenerator -98.76 26.70 3
*
* Remember that January is 2, February is 3 and so on.
*/
/* @author: Karen Li
*/
public class WeatherGenerator {
static final int WET = 1; // Use this value for a wet day
static final int DRY = 2; // Use this value for a dry day
// Number of days in each month, January is index 0, February is index 1
static final int[] numberOfDaysInMonth = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
/*
* Given a location (longitude, latitude) in the USA and a month of the year, the method
* returns the forecast for the month based on the drywet and wetwet transition
* probabilities tables.
*
* month will be a value between 2 and 13: 2 corresponds to January, 3 corresponds to February
* and so on. These are the column indexes of each month in the transition probabilities tables.
*
* The first day of the month has a 50% chance to be a wet day, 0-0.49 (wet), 0.50-0.99 (dry)
*
* Use StdRandom.uniform() to generate a real number uniformly in [0,1)
*
*/
public static int[] oneMonthForecast(double longitute, double latitude,
int month, double[][] drywet, double[][] wetwet) {
int[] forecast = new int[numberOfDaysInMonth[month - 2]];
for (int i = 0; i < drywet.length; i++){
if (drywet[i][0] == longitute && drywet[i][1] == latitude){
break;
}
for (int j = 1; j <= forecast.length; j++){
if (j == 1){
if (StdRandom.uniform() <= .49){
forecast[j - 1] = WET;
}
else {
forecast[j - 1] = DRY;
}
}
else {
if (forecast[j - 2] == WET){
if (StdRandom.uniform() > wetwet[i][month]){
forecast[j - 1] = DRY;
}
else {
forecast[j - 1] = WET;
}
} else {
if (StdRandom.uniform() <= drywet[i][month]){
forecast[j - 1] = WET;
}
else {
forecast[j - 1] = DRY;
}
}
}
}
}
return forecast;
}
/*
* Returns the number of mode (WET or DRY) days in forecast.
*/
public static int numberOfWetDryDays (int[] forecast, int mode) {
int sum = 0;
for (int i = 0; i < forecast.length; i++){
if (forecast[i] == mode){
sum += 1;
}
}
return sum;
}
/*
* Returns the longest number of consecutive mode (WET or DRY) days in forecast.
*/
public static int lengthOfLongestSpell (int[] forecast, int mode) {
int kl = 0;
int sum = 0;
for (int i = 0; i < forecast.length; i++){
if (forecast[i] == mode){
sum++;
} else {
sum = 0;
}
if (kl < sum){
kl = sum;
}
}
return kl;
}
/*
* Reads numberOfLocations probabilites into arrayToFill.
*
* Transition probabilities file format:
* Longitude Latitude January February March April May June July August September October November December
* -97.58 26.02 0.76 0.75 0.77 0.74 0.80 0.86 0.94 0.97 0.89 0.77 0.74 0.77
*/
public static void readTransitionProbabilities ( double[][] arrayToFill,
int numberOfLocations ) {
int row = 0;
while (row < numberOfLocations) {
arrayToFill[row][0] = StdIn.readDouble(); // Longitute
arrayToFill[row][1] = StdIn.readDouble(); // Latitude
arrayToFill[row][2] = StdIn.readDouble(); // January
arrayToFill[row][3] = StdIn.readDouble(); // February
arrayToFill[row][4] = StdIn.readDouble(); // March
arrayToFill[row][5] = StdIn.readDouble(); // April
arrayToFill[row][6] = StdIn.readDouble(); // May
arrayToFill[row][7] = StdIn.readDouble(); // June
arrayToFill[row][8] = StdIn.readDouble(); // July
arrayToFill[row][9] = StdIn.readDouble(); // August
arrayToFill[row][10] = StdIn.readDouble(); // Septmber
arrayToFill[row][11] = StdIn.readDouble(); // October
arrayToFill[row][12] = StdIn.readDouble(); // November
arrayToFill[row][13] = StdIn.readDouble(); // December
row += 1;
}
}
/*
*
* Expects files in the same directory. The first (drywet.txt) contains
* transition probabilities that reflects how often the weather changes
* from wet to dry. The second (wetwet.txt) is transition probabilities
* that reflects that the weather remains wet from one day to the next.
*
*/
public static void populateTransitionProbabilitiesArrays(double[][] drywet,
double[][] wetwet, int numberOfLocations) {
// Read transition probabilities that reflects how often the weather
// changes from wet to dry into 2D array drywet.
// The first line on the file has number of locations (lines)
StdIn.setFile("drywet.txt");
readTransitionProbabilities(drywet, numberOfLocations);
// Read transition probabilities that reflects that the weather remains
// wet from one day to the next into 2D array wetwet.
// The first line on the file has number of locations (lines)
StdIn.setFile("wetwet.txt");
readTransitionProbabilities(wetwet, numberOfLocations);
}
/*
*
* Reads the files containing the transition probabilities for US locations.
*
* To find
*
* Execution:
* java WeatherGenerator -97.58 26.02 3
*
*
*/
public static void main (String[] args) {
int numberOfRows = 4001; // Total number of locations
int numberOfColumns = 14; // Total number of 14 columns in file
// File format: longitude, latitude, 12 months of transition probabilities
// Allocate and populate arrays that hold the transition probabilities
double[][] drywet = new double[numberOfRows][numberOfColumns];
double[][] wetwet = new double[numberOfRows][numberOfColumns];
populateTransitionProbabilitiesArrays(drywet, wetwet, numberOfRows);
/*** WRITE YOUR CODE BELLOW THIS LINE. DO NOT erase any of the lines above. ***/
// Read command line inputs
double longitute = Double.parseDouble(args[0]);
double latitude = Double.parseDouble(args[1]);
int month = Integer.parseInt(args[2]);
int[] forecast = oneMonthForecast(longitute, latitude, month, drywet, wetwet);
int drySpell = lengthOfLongestSpell(forecast, DRY);
int wetSpell = lengthOfLongestSpell(forecast, WET);
StdOut.println("There are " + forecast.length + " days in the forecast for month " + month);
StdOut.println(drySpell + " days of dry spell.");
for ( int i = 0; i < forecast.length; i++ ) {
// This is the ternary operator. (conditional) ? executed if true : executed if false
String weather = (forecast[i] == WET) ? "Wet" : "Dry";
StdOut.println("Day " + (i+1) + " is forecasted to be " + weather);
}
}
}
Karen Li 