So I'm working on a program which is supposed to randomly put people in 6 rooms (final input is the list of rooms with who is in each room). So I figured out how to do all that.
//this is the main sorting sequence:
for (int srtM = 0; srtM < Guys.length; srtM++) {
done = false;
People newMove = Guys[srtM]; //Guys is an array of People
while (!done) {
newMove.rndRoom(); //sets random number from 4 to 6
if (newMove.getRoom() == 4 && !room4.isFull()) {
room4.add(newMove); //adds person into the room4 object rList
done = true;
} else if (newMove.getRoom() == 5 && !room5.isFull()) {
room5.add(newMove);
done = true;
} else if (newMove.getRoom() == 6 && !room6.isFull()) {
room6.add(newMove);
done = true;
}
}
The problem now is that the code for reasons I don't completely understand (something with the way I wrote it here) is hardly random. It seems the same people are put into the same rooms almost every time I run the program. For example me, I'm almost always put by this program into room 6 together with another one friend (interestingly, we're both at the end of the Guys array). So how can I make it "truly" random? Or a lot more random than it is now?
Thanks in advance!
Forgot to mention that "rndRoom()" does indeed use the standard Random method (for 4-6) in the background:
public int rndRoom() {
if (this.gender == 'M') {
this.room = (rnd.nextInt((6 - 4) + 1)) + 4;
}
if (this.gender == 'F') {
this.room = (rnd.nextInt(((3 - 1) + 1))) + 1;
}
return this.room;
}
if you want it to be more random try doing something with the Random method, do something like this:
Random random = new Random();
for (int i = 0; i < 6; i++)
{
int roomChoice = random.nextInt(5) + 1;
roomChoice += 1;
}
of course this is not exactly the code you will want to use, this is just an example of how to use the Random method, change it to how you want to use it.
Also, the reason I did random.nextInt(5) + 1; is because if random.nextInt(5) + 1; gets you a random number from 0 to 5, so if you want a number from 1 to 6 you have to add 1, pretty self explanatory.
On another note, to get "truly" random is not as easy as it seems, when you generate a "random" number it will use something called Pseudo random number generation, this, is basically these programs produce endless strings of single-digit numbers, usually in base 10, known as the decimal system. When large samples of pseudo-random numbers are taken, each of the 10 digits in the set {0,1,2,3,4,5,6,7,8,9} occurs with equal frequency, even though they are not evenly distributed in the sequence.
There might be something wrong with code you didn't post.
I've build a working example with what your classes might be, and it is distributing pretty randomly:
http://pastebin.com/u8sZRxi6
OK so I figured out why the results don't seem very random. So the room sorter works based on an alphabetical people list of 18 guys. There are only 3 guy rooms (rooms 4, 5 and 6) So each guy has a 1 in 3 chance to be put in say, room 6. But each person could only possibly be in 2 of the 6 spots in each room (depending on where they are in the list).
The first two people for example, could each only be in either the first or second spot of each room. By "spot" I mean their place in the room list which is printed in the end. Me on the other hand am second last on the list, so at that point I could only be in either the last or second last spot of each room.
Sorry if it's confusing but I figured out this is the reason the generated room lists don't appear very random - it's because only the same few people could be put in each room spot every time. The lists are random though, it's just the order in which people appear in each list which is not random.
So in order to make the lists look more random I had to make people's positions in the room random too. So the way I solved this is by adding a shuffler action which mixes the Person arrays:
public static void shuffle(Person[] arr) {
Random rgen = new Random();
for (int i = 0; i < arr.length; i++) {
int randPos = rgen.nextInt(arr.length);
Person tmp = arr[i];
arr[i] = arr[randPos];
arr[randPos] = tmp;
}
}
TL;DR the generated room lists were random - but since the order of the people that got put into the rooms wasn't random the results didn't look very random. In order to solve this I shuffled the Person arrays.
Related
I currently have java homework that I would appreciate some help with. We are to calculate a team record scenario.
We are given the following numbers:
Team1 Points
{23,45,65,20}
Opponent Points
{20,30,20,18}
I threw these into an array. I also created a public boolean. Basically, you are to pull these points from the array to the boolean? And let the boolean decide which team won? Obviously team1 has won, but we are supposed to let the computer decide, not the human.
Here is my code:
public class TeamScore {
public static boolean Winner(int team1Points, int opponentPoints) {
if (team1Points > opponentPoints) {
return true;
} else {
return false;
}
}
public static void main(String[] args) {
// Scanner in = new Scanner(System.in);
int[] team1Points = { 23, 45, 65, 20 };
int[] opponentPoints = { 20, 30, 20, 18 };
int team1 = 1;
int opponent = 1;
for (int i = 0; i < 5; i++) {
if (Winner(team1Points[i], opponentPoints[1])) {
team1 += 1;
} else {
opponent += 1;
}
}
for (int i = 0; i < 5; i++) {
if (team1 > 0 && opponent == 0) {
System.out.println("Team 1 has the perfect record!");
} else {
System.out.println("Win" + Arrays.toString(team1Points));
System.out.println("Loss" + Arrays.toString(opponentPoints));
}
}
}
Could anyone possibly help me? I am currently in programming II, but I did not have the best teacher in programming I. Any help would be appreciated!
EDIT:
I do not think this is a duplicate question because I already can fix it by changing the variable i-->1. My problem is that the computer thinks that team1 has already won regardless of the score.
When I run the code I am getting an java.lang.ArrayIndexOutOfBoundsException error. However when I change team1Points[i] to team1Points[1] then it goes okay and tells me that "Team 1 has the perfect record!". However, if I change some of the array values for team1Points to be less than opponentPoints then it still says "Team 1 has the perfect record!".
Not sure why you have a method Winner (also as Kevin said, it should be winner because of naming conventions) which turns ´(a > b)´ into a large if-statement. Similar stuff appear elsewhere in your code.
Your variables ´team1, opponent = 1´ inexplicably start with the value 1, am I to understand this as a way for your code to imply to a reader that both teams initialize at a win? Using 0 would probably make more sense.
Your game ought to crash from an indexoutofboundsexception at ´team1Points[i]´, as you have arrays of length 4, but your loops runs 5 times (the currently used range is [0-4], inclusive). Changing your loops to i=1 won't help, as the issue is that you eventually encounter team1Points[4] due to the i < 5 statement.
I don't know what game you are modelling or how it works, but the comparison ´Winner(team1Points[i],opponentPoints[1])´ looks like a blatant error to me (you always look at the opponents score for their second round).
Why are you printing your results 5 times? If you want to print the first message only when team1 won all rounds and the point for each round otherwise, you would need to use the loops counter as an index to the arrays in second case. First case should break loop so its not written five times, in addition you don't need to check team1>0 && opponent==0 as it's enough to only check if ´opponent==0´ (speaking of this conditional, it only works if you initialize the variables at 0 as I mentioned before). You could have checked if team1 equals size of the array instead, but imo thats more of a hassle than opponent==0.
Lastly, please fix your indenting. use the preview system so you can make double sure before posting.
Edit: Kevin also brings up a good point that you should be using the length of the array in your loops second statement.
DISCLAIMER : I DO NOT WANT THE ANSWER TO THIS PROBLEM. I SIMPLY NEED SOME GUIDANCE.
I want to perform Monte Carlo analysis on the infamous Birthday Paradox (determining the probability that at least 2 people in a given group share the same birthday) using a HashSet.
Now when I run this, the collisionCount is WAY lower than I expected it to be.First, I was expecting the collisionCount for a group of 10 people to be 11446 (or a probability of 0.11446). Then by the time I got to 100 people, I was expecting the collisionCount to be 100,000 (with a probability of 1.0). But instead, for every 10 people, the collisionCount only counts by 1 (10 people: 1 collision, 20 people: 2 collisions, 30 people: 3 collisions, etc).
Here is the code I have wrote so far :
import java.util.HashSet;
import java.util.Random;
import java.util.Set;
public class BirthdayParadox
{
public static void main(String [] args)
{
Random rand = new Random();
int tests = 100000;
int collisionCount = 0;
for(int people = 10; people <= 100; people += 10)
{
Set<Integer> birthdays = new HashSet<>(365);
birthdays.add(rand.nextInt(365));
for(int runs = 0; runs < tests; runs++)
{
int randomBirthday = rand.nextInt(365);
if(birthdays.contains(randomBirthday))
{
collisionCount++;
break;
}
birthdays.add(randomBirthday);
}
float prob = (float)collisionCount / tests;
System.out.println("After " + tests + " tests there were " +
collisionCount + " occurrences of shared " +
" birthdays in a set of " + people + " people.");
System.out.println("Probability : " + prob);
}
}
}
I guess my question is : Am I not doing something right with either of my for-loops in order to get the collisionCount to count correctly?
I am new to learning Java and I am new to the Stack Overflow community and am still learning the ropes. Any help/ advice/ tips are greatly appreciated.
Your problem appears to be that you are missing one of your loops.
Notice that your runs loop is broken by the first collision. This means that your value will never be more than 1.
Also, you never use your people variable inside the inner loop except when outputting results.
What you need to do is run your simulation 100_000 times. The way to do this is to place logic within your runs loop that checks if people people will have a birthday collision and then iterate your collision count.
I think that the java solution is not the best, this probably it is the problem why you have a difference between the simulation and the mathematical values. What i understand for the problem is that you have to determine for a group of 10 people (in this case) how many of them share the same birthday. To do that you have to random an array of 10 with number from 0 to 365 (days of the year) and count how many of them are the same. You have to do that severals time (100000 in your case).
I think that you have to invert the FOR order. I mean..
for(int runs = 0; runs < tests; runs++)
{
//initialize an array of 10
for(int people = 0; people <= 10; people +=1)
{
//random birthdayDay
//array [people] = rand.nextInt(365);
}
//check if there is a collision
//If there is one you have to increase you success variable in 1
}
//calculate the probability
I try to help you, doing kind of pseudocode.
Hope that this help you a little bit.
Regards
Arturo.
Summary: I need a function based on the output. The problem is
connecting Eclipse or a Java code with another software.
I'm studying Physics. I needed a code that works the following way:
first, it declares a random number n;
then it outputs a "winner" number (based on some rules; the code
itself is irrelevant now I think), 20 times (but should be more,
first I need something to record the values, though).
I have n and 20 other numbers which are each between 1 and n (including 1 and n). I want, after compiling the code once, to see the 20 values, how they are distributed (for example, are they around one particular number, or in a region, is there a pattern (this is based on the rules, of course)).
The problem is, I'm only familiar with basic Java (I used eclipse), and have no clue on how I should register for example 2000 instead of the 20 numbers (so for an n number the code should print 2000 or more numbers, which should appear on a function: domain of the function is 1, 2, ..., n, and range is 0, 1, ..., 2000, as it might happen that all 2000 numbers are the same). I thought of Excel, but how could I connect a Java code with it? Visual interpretation is not necessary, although it would make my work easier (I hope, at least).
The code:
import java.util.Random;
public class korbeadosjo {
public static void main(String Args[]){
Random rand = new Random();
int n = (rand.nextInt(300)+2);
System.out.println("n= " + n);
int narrayban = n-1;
int jatekmester = n/2;
int jatekmesterarrayban = jatekmester-1;
System.out.println("n/2: " + jatekmester);
for(int i=0; i<400; i++){
int hanyembernelvoltmar = 1;
int voltmar[] = new int[n];
voltmar[jatekmesterarrayban]=1;
int holvan=jatekmester;
int holvanarrayban = holvan-1;
fori: for(;;){
int jobbravagybalra = rand.nextInt(2);
switch(jobbravagybalra){
case 0: //balra
if(holvanarrayban ==0){
holvanarrayban = narrayban;
}else {
--holvanarrayban;
};
if(voltmar[holvanarrayban]==0){
voltmar[holvanarrayban] =1;
++hanyembernelvoltmar;
}
break;
case 1: //jobbra
if(holvanarrayban == narrayban){
holvanarrayban = 0;
} else {++holvanarrayban;};
if(voltmar[holvanarrayban]==0){
voltmar[holvanarrayban]=1;
++hanyembernelvoltmar;
}
break;
}if(hanyembernelvoltmar==n){
System.out.println(holvanarrayban+1);
break fori;
}}}}}
basic Java (I used eclipse)
Unrelated.
I could only find two prompts in your question:
How to create statistics from output of Java code?
You are likely not wanting to get the output alone. Use those numbers in your Java program to find what you want and output it.
How did you store 2000 values? An array, list, queue...? So also iterate on that data structure and generate the statistics you need.
I thought of Excel, but how could I connect a Java code with it?
There is this site.
static int n = -1;
private static int repeatBuffer[] = new int[10];
static {
repeatBuffer[0] = 0;
//and more
repeatBuffer[9] = 9;
}
static public void randomize() {
do {
Random r = new Random();
randomNumber = r.nextInt(20);
} while (!uniqueInt(randomNumber));
Log.e(TAG, "" + randomNumber); //here I need have a unique int
}
private static Boolean uniqueInt(int random) {
for (int i = 0; i < 9; i++) {
if (random == repeatBuffer[i]) {
return false;
}
}
if (++n > 9)
n = 0;
repeatBuffer[n] = random;
return true;
}
Sometimes I'm getting same int twice, I'm wondering where is the problem? And is it even work? I spend quite a lot of time on this, and I give up. I think I need some minor tweaks in code :)
An easier way to get a random int is to create a List of integers List<Integer>, adding it with numbers that you would like to have. Then shuffling the List using Collections.shuffle(list);. Now start reading from the beginning of the list and you will get a unique random int each time.
Just make sure that each time you "read" a number from the list, either remove it from the list or increase the index for where you read.
That's the normal behavior of a random number generator, it's correct to generate repeated numbers as long as the number distribution remains uniform.
If you need a set of unique random numbers, you can generate them inside a loop and ask at every iteration if the newly generated number is present in the set of generated numbers. If not, add it, if yes, keep iterating - until the set has the desired size.
Er, a unique random between 1 and 20? What happens when it runs the 21st time?
Try making a List of the Integers between 1 and 20. Use Collections.shuffle() to shuffle the list. Then pop the first item off the front of the list and use that.
I created two methods for my Bingo Game in Java. One method creates a new board which populates the Bingo Board with integers according to the Bingo rule (1-75). My second method generates random numbers with a range of 1 - 75.
public static int drawNum(){
Random rand = new Random();
int num = rand.nextInt(75)+1;
return num;
}
public static void bingoCard(){
int [][]card=new int [5][5];
ArrayList<Integer> alreadyUsed = new ArrayList<Integer>();
boolean valid = false;
int tmp = 0;
for(int i = 0; i <= 4; i++){
for(int row = 0; row < card.length; row++){
while(!valid){
tmp = (int)(Math.random() * 15) + 1 + 15 * i;
if(!alreadyUsed.contains(tmp)){
valid = true;
alreadyUsed.add(tmp);
}
}
card[row][i] = tmp;
valid = false;
}
}
card[2][2] = 0;
//create array to make title.
String title []={"B","I","N","G","O"};
for(int i=0;i<title.length;i++){
System.out.print(title[i]+ "\t");
}
System.out.println();
for(int row=0;row<card.length;row++){
for(int col=0;col<card[row].length;col++){
System.out.print(card[row][col]+ "\t");
}
System.out.println();
}
}
What I need help with is, how do I check whether or not the drawNum() method corresponds to any values stored inside my bingoCard() array? If so, print out a new array with the integers filled in. If the condition is met for a bingo, then you win.
I hope I don't make it sound like I want you to do it for me, but I am confused as to how to start coding that part. Thank you.
This my recommendation - Learn Object Oriented Programming immediately
I see you are using objects provided in the JDK, so why not learn to make your own?
Make two classes with the following methods (-) and members (+) (PS. This is not a formal way to document code)
BingoCard
+list of numbers on card
-reset() : gets new numbers for this card
-test(BingoDrawer) : Tests to see if this card won on this drawing
-toString() : returns a String representation of this card
BingoDrawer
+list of numbers drawn
-reset() : draws new numbers
-hasNumber(int number) : tests if this number was drawn
-toString() : returns a String representation of this drawing
One more suggestions
Instead of keeping track of what you used, keep track of what you have not used, it will make things much easier because you can just choose stuff from that list randomly. Unlike your current action which is choosing (a logical number) from thin air and hoping (which causes issues) it is not a collision
If you follow my recommendation you can write code like this
public static void main(String[] args) {
BingoCard bc = new BingoCard();
BingoDrawer bd = new BingoDrawer();
while(thePlayerWantsToPlay()) { //function to be defined by you
bc.reset();
bd.reset();
System.out.println(bc);
System.out.println(bd);
System.out.println(bc.test(bd));
}
}
You can take it a step further and make a BingoGame class and do what I did in main there and just create an instance of BingoGame and call some start method on the object.
For checking if you have the number in your board, read through the board in a similar manner as you do for the already_used numbers, except with the number the user just entered.
The conditions for the user to win should be checked after the board has another number guessed.
There are a few ways to do this, a simple one would be to iterate over every possible pattern that could win, checking to see if there are tokens there.
All of this would be in a loop, that goes a little like this:
Set up board via user entering numbers.
Start loop
set either a timer to wait for, or wait for a keypress (so the game doesn't just play really fast)
Get random number
Possibly add to board
Check if winner
if winner, break the loop and do something else.
Print the new board out.
(end of loop)
If they got here, that could mean they won!
Wait to exit
You can just write it out as pseudo-code and fill in the methods after that. It usually helps to work on these things in a top-down fashion. So, for bingo you might have:
board = generateBoard();
while (!bingoFound(board)) {
number = drawNumber();
board = stampNumbers(board, number);
}
If that makes sense, you can go a step deeper and define each method. For example, bingoFound might look like:
public boolean bingoFound(int[][] board) {
boolean wasFound = bingoRowFound(board)
|| bingoColFound(board)
|| bingoDiagonalFound(board);
return wasFound;
}
Again, I've defined everything in (mostly) pseudo-code. If this looks ok, you can move a step deeper. Let's define the bingoRowFound method.
public boolean bingoRowFound(int[][] board) {
for (int row = 0; row < NUM_ROWS; row++) {
boolean rowIsABingo = true;
for (int col = 0; col < NUM_COLS; col++) {
// We have to check that everything up until this point has
// been marked off. I am using -1 to indicate that a spot has
// been marked.
rowIsABingo = rowIsABingo && board[row][col] == -1;
}
if (rowIsABingo) { return rowIsABingo; }
}
return false; // If we didn't find a bingo, return false.
}
Some of the methods (like drawNumber) will be really easy to implement. Others, like looking for a diagonal bingo might be a bit more difficult.
Feb 12 2014 Update:
Retracted code, since this was a college course assignment, and I want to prevent people just copying the code. I almost got in trouble for being accused of sharing code (which is a nono in assignments) when another student lifted my code from my Github repo and sent it in as their own.
There were two classes, one main class and a class to hold my methods and constructors.
BINGOFINAL.java was my main class.
Bingo_Card.java held my constructor and methods.
If you want to run this, make sure you create a new project called BINGOFINAL, and put Bingo_Card.java into that same */src/ extension.