I'm creating a random number generator which then sorts the digits from largest to smallest. Initially it worked but then I changed a few things. As far as I'm aware I undid all the changes (ctrl + z) but now I have errors at the points where i try to call the methods. This is probably a very amateur problem but I haven't found an answer. The error i'm met with is "method in class cannot be applied to given types"
Here's my code:
public class RandomMath {
public static void main(String[] args) {
String bigger = bigger(); /*ERROR HERE*/
System.out.println(bigger);
}
//create method for generating random numbers
public static int generator(int n){
Random randomGen = new Random();
//set max int to 10000 as generator works between 0 and n-1
for(int i=0; i<1; i++){
n = randomGen.nextInt(10000);
// exclude 1111, 2222, 3333, 4444, 5555, 6666, 7777, 8888, 9999, 0000
if((n==1111 || n==2222 || n==3333 || n ==4444 || n==5555)
||(n==6666 || n==7777 || n==8888 || n==9999 || n==0000)){
i--;
}
}
return n;
}
//create method for denoting the bigger number
public static String bigger(int generated){
generated = generator(); /*ERROR HERE*/
System.out.println(generated);
int[] times = new int[10];
while (generated != 0) {
int val = generated % 10;
times[val]++;
generated /= 10;
}
String bigger = "";
for (int i = 9; i >= 0; i--) {
for (int j = 0; j < times[i]; j++) {
bigger += i;
}
}
return bigger;
}
}
You have not defined a method bigger(), only bigger(int generated). Therefore, you must call your bigger method with an integer parameter.
Related
I'm creating two classes called stop watch and random numbers, which I have already done, but I needed to create a test program that would measure the execution time of sorting 100,000 numbers using selection sort. I know how to create a selection sort, I just don't know how to take the random numbers class and put it together with the selection sort, I get the error message "incompatible types random numbers cannot be converted to int" I hope someone can help me.
My random numbers class
import java.util.Random;
public class randomnumbers {
Random ran1 = new Random();
private int size;
public randomnumbers(){
size = 100000;
}
public int getSize(){
return size;
}
public void setSize(int newSize){
size = newSize;
}
public int [] createArray(int [] size){
for (int i = 0; i < size.length; i++){
size[i] = ran1.nextInt();
}
return size;
}
public static void printArray (int [] array){
for (int i = 0; i < array.length; i++){
if (i < 0){
System.out.println(array[i] + " ");
}
}
}
}
My test Program
public static void main (String [] args){
// Create a StopWatch object
StopWatch timer = new StopWatch();
//create random numbers
randomnumbers numbers = new randomnumbers();
//Create the size of the array
numbers.getSize();
// Invoke the start method in StopWatch class
timer.start();
//sort random numbers
selectionSort();
// Invoke the stop method in StopWatch class
timer.stop();
// Display the execution time
System.out.println("The execution time for sorting 100,000 " +
"numbers using selection sort: " + timer.getElapsedTime() +
" milliseconds");
}
// selectionSort performs a selection sort on an array
public static void selectionSort(int[] array) {
for (int i = 0; i < array.length - 1; i++) {
int min = array[i];
int minIndex = i;
for (int j = i + 1; j < array.length; j++) {
if (array[j] < min) {
min = array[j];
minIndex = j;
}
}
if (i != minIndex) {
array[minIndex] = array[i];
array[i] = min;
}
}
}
}
Where exactly are you getting "incompatible types random numbers cannot be converted to int" error?
There are multiple issues with the code:
Unconventional naming
size field is in randomnumbers class is used as actual array size in constructor but in createArray it's overshadowed with a parameter of the same name but different type and meaning.
You are not passing any array to selectionSort in Main. This is where I get compile error on your code.
printArray has if (i < 0) condition that is false for all ran1.nextInt() numbers so it will not print anything.
Feeding selectionSort with numbers.createArray(new int[numbers.getSize()]) compiles and ends up sorting the array.
I am having an issue with my merge sort, when I print out my sortedArray it only returns [ 0.0, 0.0.....] Im not sure if there is an error in my sort code or in my print line or if it has to do with doubles. The code I am us posted below.
By calling System.out.println(toString(sortedArray) I get an even more obscure answer.
Thanks for any help.
package mergesort;
import java.util.Arrays;
import java.util.Random;
public class mergesort {
public static void main(String[] args) {
double[] array = getIntArray();
long before = System.nanoTime();
double[] sortedArray= mergeSort(array);
System.out.println("Sorting took "+ (System.nanoTime() - before) +" nanoseconds ");
System.out.println(toString(array) + "\n\n" + toString(sortedArray) + "\n main method completed in: " + (System.nanoTime() - before) + " nanoseconds.");
}
private static String toString(double[] array) {
StringBuilder sb = new StringBuilder("[ ");
double len = array.length;
for(int i = 0; i < len - 1; i++) {
sb.append(array[i] + ", ");
}
sb.append(array[(int) (len - 1)] + " ]");
return sb.toString();
}
public static double[] mergeSort(double[] array) {
if (array.length <= 1) {
return array;
}
int half = array.length / 2;
return merge(mergeSort(Arrays.copyOfRange(array, 0, half)),
mergeSort(Arrays.copyOfRange(array, half, array.length)));
}
private static double[] merge(double[] ds, double[] ds2) {
int len1 = ds.length, len2 = ds2.length;
int totalLength = len1 + len2;
double[] result = new double[totalLength];
int counterForLeft =0,counterForRight=0,resultIndex=0;
while(counterForLeft<len1 || counterForRight < len2){
if(counterForLeft<len1 && counterForRight < len2){
if(ds[counterForLeft]<= ds2[counterForRight]){
result[resultIndex++] =(int) ds[counterForLeft++];
} else {
result[resultIndex++] =(int) ds2[counterForRight++];
}
}else if(counterForLeft<len1){
result[resultIndex++] = (int) ds[counterForLeft++];
}else if (counterForRight <len2){
result[resultIndex++] =(int) ds2[counterForRight++];
}
}
return result;
}
private static double[] getIntArray() {
double[] array = new double[10000];
Random random = new Random();
for(int i = 0; i < 10000; i++) {
array[i] = (random.nextDouble() * .99999);
}
return array;
}
}
In the merge method, when copying from one of the input arrays to the results, you cast to int. For example:
result[resultIndex++] =(int) ds[counterForLeft++];
All your doubles are in the range [0...1), so the result of casting any of them to int is zero. Just get rid of those casts, and you will keep your numbers in the merge result.
As an additional tip, it is much easier to debug small problems than large ones. It failed for any size greater than 2, so you should have been debugging with size 2, not 10000.
I'm having a problem with getting my XOR neural network to converge. It has two inputs, 2 nodes in the hidden layer, and one output node. I think it has something to do with my back propagation algorithm but I have tried to figure out where in it the problem occurs but I can't. I have also looked extensively over all the algorithms and they appear to be all correct.
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Random;
public class NeuralNetwork {
public static class Perceptron {
public ArrayList<Perceptron> inputs;
public ArrayList<Double> inputWeight;
public double output;
public double error;
private double bias = 1;
private double biasWeight;
public boolean activationOn = false;
//sets up non input layers
public Perceptron(ArrayList<Perceptron> in) {
inputWeight = new ArrayList<Double>(in.size());
inputs = in;
initWeight(in.size());
}
//basic constructor
public Perceptron() { }
//generate random weights
private void initWeight(int size) {
Random generator = new Random();
for(int i=0; i<size; i++)
inputWeight.add(i, ((generator.nextDouble())));
biasWeight = (generator.nextDouble());
}
//calculate output based on current outputs of last layer
public double calculateOutput() {
double num = 0;
num = bias*biasWeight;
for(int i=0; i<inputs.size(); i++)
num += inputs.get(i).output * inputWeight.get(i);
output = num;
if(activationOn)
output = sigmoid(output);
else
output = threshold(output);
return output;
}
//methods used for learning
//calculate output error
public double calcOutputError(double expected){
error = output * (1 - output) * (expected - output);
return error;
}
//calculate node blame
public void blame(double outError, double outWeight) {
error = output * (1 - output) * outWeight * outError;
}
//adjust weights
public void adjustWeight() {
double alpha = .5;
double newWeight = 0;
for(int i=0; i<inputs.size(); i++) {
newWeight = inputWeight.get(i) + alpha * inputs.get(i).output * error;
inputWeight.set(i, newWeight);
}
//adjust bias weight
newWeight = biasWeight + alpha * bias * error;
biasWeight = newWeight;
//System.out.println("Weight " + biasWeight);
}
//returns the sigmoid of x
private double sigmoid(double x) {
return (1 / ( 1 + Math.pow(Math.E, -x)));
}
//returns threshold of x
private double threshold(double x) {
if(x>=0.5)
return 1;
else
return 0;
}
}
//teaches a neural network XOR
public static void teachXOR(ArrayList<Perceptron> inputs, ArrayList<Perceptron> hidden, Perceptron output) {
int examples[][] = { {0,0,0},
{1,1,0},
{0,1,1},
{1,0,1} };
boolean examplesFix[] = {false, false, false, false};
int layerSize = 2;
boolean learned = false;
boolean fixed;
int limit = 50000;
while(!learned && limit > 0) {
learned = true;
limit--;
//turn on using activation function
for(int i=0; i<2; i++)
hidden.get(i).activationOn = true;
output.activationOn = true;
for(int i=0; i<4; i++) {
examplesFix[i] = false;
//set up inputs
for(int j=0; j<layerSize; j++)
inputs.get(j).output = examples[i][j];
//calculate outputs for hidden layer
for(int j=0; j<layerSize; j++)
hidden.get(j).calculateOutput();
//calculate final output
double outValue = output.calculateOutput();
System.out.println("Check output " + examples[i][0] + "," + examples[i][1] + " = " + outValue);
if(((outValue < .5 && examples[i][2] == 1) || (outValue > .5 && examples[i][2] == 0))) {
learned = false;
examplesFix[i] = true;
}
}
//turn on using activation function
for(int i=0; i<2; i++)
hidden.get(i).activationOn = true;
output.activationOn = true;
//teach the nodes that are incorrect
if(!learned && limit >= 0) {
for(int i=0; i<4; i++) {
if(examplesFix[i]) {
fixed = false;
while(!fixed) {
//System.out.println("Adjusting weight: " + examples[i][0] + "," + examples[i][1] + " --> " + examples[i][2]);
for(int j=0; j<layerSize; j++)
inputs.get(j).output = examples[i][j];
//calculate outputs for hidden layer
for(int j=0; j<layerSize; j++)
hidden.get(j).calculateOutput();
//calculate final output
double outValue = output.calculateOutput();
if((outValue >= .5 && examples[i][2] == 1) || (outValue < .5 && examples[i][2] == 0)) {
fixed = true;
}
else {
double outError = output.calcOutputError(examples[i][2]);
//blame the hidden layer nodes
for(int j=0; j<layerSize; j++)
hidden.get(j).blame(outError, output.inputWeight.get(j));
//adjust weights
for(int j=0; j<layerSize; j++)
hidden.get(j).adjustWeight();
output.adjustWeight();
}
}
}
}
}
}
//if(limit <= 0)
// System.out.println("Did not converge");//, error: " + output.error);
//System.out.println("Done");
}
//runs tests for XOR, not complete
public static void runXOR(ArrayList<Perceptron> inputs, ArrayList<Perceptron> hidden, Perceptron output) throws IOException {
//create new file
PrintWriter writer;
File file = new File("Test.csv");
if(file.exists())
file.delete();
file.createNewFile();
writer = new PrintWriter(file);
ArrayList<String> positive = new ArrayList<String>();
ArrayList<String> negative = new ArrayList<String>();
//turn off using activation function
for(int i=0; i<2; i++)
hidden.get(i).activationOn = false;
output.activationOn = false;
//tests 10,000 points
for(int i=0; i<=100; i++) {
for(int j=0; j<=100; j++) {
inputs.get(0).output = (double)i/100;
inputs.get(1).output = (double)j/100;
//calculate outputs for hidden layer
for(int k=0; k<2; k++)
hidden.get(k).calculateOutput();
//calculate final output
double outValue = output.calculateOutput();
//keep track of positive and negative results
if(outValue >= .5) {
positive.add((double)i/100 + "," + (double)j/100 + "," + outValue);
//writer.println((double)i/100 + "," + (double)j/100 + ",1");
}
else if(outValue < .5) {
negative.add((double)i/100 + "," + (double)j/100 + "," + outValue);
//writer.println((double)i/100 + "," + (double)j/100 + ",0");
}
}
}
//write out to file
writer.println("X,Y,Positive,X,Y,Negative");
int i = 0;
while(i<positive.size() && i<negative.size()) {
writer.println(positive.get(i) + "," + negative.get(i));
i++;
}
while(i<positive.size()) {
writer.println(positive.get(i));
i++;
}
while(i<negative.size()) {
writer.println(",,," + negative.get(i));
i++;
}
writer.close();
}
//used for testing
public static void main(String[] args) throws IOException {
int layerSize = 2;
ArrayList<Perceptron> inputLayer;
ArrayList<Perceptron> hiddenLayer;
Perceptron outputLayer;
//XOR neural network
inputLayer = new ArrayList<Perceptron>(layerSize);
hiddenLayer = new ArrayList<Perceptron>(layerSize);
//for(Perceptron per : inputLayer)
// per = new Perceptron();
for(int i=0; i<layerSize; i++)
inputLayer.add(new Perceptron());
for(int i=0; i<layerSize; i++)
hiddenLayer.add(new Perceptron(inputLayer));
outputLayer = new Perceptron(hiddenLayer);
teachXOR(inputLayer, hiddenLayer, outputLayer);
runXOR(inputLayer, hiddenLayer, outputLayer);
}
}
First, your code has very peculiar structure and will be hard to debug. I would consider writing it from scratch, with more clear structure, less internal fields, and more actual functions returning values.
One major error (possibly not the only one) is your distinction between output and learnOutput in hidden layer. When you calculate activation of the output layer you actually use "output" field, while you should use learnOutput (which is the only one actually using sigmoid activation).
Furthermore - if you correctly restructure your code you could create unit test for numerical gradient testing, and this is what you should always do when working with neural networks/other gradient trained machines. In this case it would show you that your gradient is incorrect.
I'm learning java and I'm having an issue with my if code not running.
In the following code I'm trying to determine if a number (variable num) is a triangle number (1,3, 6, 10 etc). The code should run through and give the "Is Triangle". However it keeps spitting out Null.
I understand this is not the most effective way to do this code, but I am trying to learn how to use Classes.
public class HelloWorld {
public static void main(String[] args) {
class NumberShape {
int num = 45;
int tri = 0;
int triplus = 0;
String triresult;
public String triangle() {
while (tri < num) {
if (tri == num) {
triresult = "Is a Triangle";
System.out.println("Is a Triangle");
} else if (tri + (triplus + 1) > num){
triresult = "Is Not a Triangle";
} else {
triplus++;
tri = tri + triplus;
}
}
return triresult;
}
}
NumberShape result = new NumberShape();
System.out.println(result.triangle());
}
}
Thanks for any help provided.
Try this code :
public class HelloWorld {
public static void main(String[] args) {
class NumberShape {
int num = 10;//Try other numbers
int tri = 0;
int triplus = 0;
int res = 0;
String triresult = "Is Not a Triangle";
int[] tab= new int[num];
public String triangle() {
//to calculate the triangle numbers
for(int i = 0; i<num; i++){
res = res + i;
tab[i]=res;
}
//To check if num is a triangle or not
for(int i = 0; i<tab.length; i++){
System.out.println(">> " + i + " : " + tab[i]);
if(tab[i]== num){
triresult = num + " Is a Triangle";
break;//Quit if the condition is checked
}else{
triresult = num + " Is Not a Triangle";
}
}
return triresult;
}
}
NumberShape result = new NumberShape();
System.out.println(result.triangle());
}
}
Hope this Helps.
Step through the loop carefully. You'll probably see that there is a case where
(tri < num)
fails, and thus you fall out of the loop, while
(tri == num)
and
(tri + (triplus + 1) > num)
both fail too, so no text gets set before you fall out.
You probably want to do your if-tests within the method on just tri, not a modification of tri, so as to reduce your own confusion about how the code is working.
any help please, so i already wrote the prog but my if statement in my for loop is not working. the prog need to generate 6 random nos,then apply bubble sort which i already did.then the user must enter 6 numbers and these numbers must be compared against the random numbers and must say whether numbers are found in the random numbers or not. here's the code. something is wrong with the if statement ` public static void main(String[] args) {
try {
int numbers[] = new int[6]; //random numbers will be stored in new array
//2 loop will be created to avoid duplication of numbers
System.out.println("Array before Bubble sort");
for (int i = 0; i < 6; i++) {
numbers[i] = (int) (Math.random() * 40);
if (i > 0) {
for (int b = 0; b < i; b++) { //
if (numbers[b] == numbers[i]) {
i--; //decrement to continue the for loop if the integer has been repeated
}
}
}
System.out.print(numbers[i] + ","); //random numbers will be printed before using sorting bubble sort
}
//sort an array using bubble sort
bubbleSort(numbers);
System.out.println(" \nArray after bubble sort");
for (int i = 0; i < 6; i++) {
System.out.print(numbers[i] + ",");
}
BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
System.out.println("\ninput 6 number between 1 and 40");
int inputNumber = Integer.parseInt(input.readLine());
for (int b = 0; b < 6; b++) {
System.out.println("number:");
int outcome=Integer.parseInt(input.readLine());
if(outcome==numbers){
System.out.println("found in random numbers");
}else{
System.out.println("not found in random numbers");
}
}
} catch (Exception e) {
System.out.println("error");
}
}
public static void bubbleSort(int[] numbers) {
int n = numbers.length;
int temp = 0;
for (int i = 0; i < n; i++) {
for (int j = 1; j < (n - i); j++) {
if (numbers[j - 1] > numbers[j]) { //swap the element
temp = numbers[j - 1];
numbers[j - 1] = numbers[j];
numbers[j] = temp;
}
}
}
}
}`
System.out.println("\ninput 6 number between 1 and 40");
//Scanner is specifically designed for getting an input purpose and introduced in Java 5,so better use it
Scanner s = new Scanner(System.in);
//you need to have nested loop here
//But the best way to search is use binary search,as you have already sorted the array
while (s.hasNextInt()) {
//one at a time from the input is put to outcome
int outcome = s.nextInt();
boolean found = false;
for (int b = 0; b < 6; b++) {
found = false;
if (outcome == numbers[b]) {
found = true;
//remember to break the inner loop if a match is found
break;
} else {
found = false;
}
}
if (found == true) {
System.out.println("found in random numbers");
} else {
System.out.println("not found in random numbers");
}