matrix

public class Matrix {
    double[]data;
    int rows;
    int cols;

    Matrix(int rows, int cols){
        this.rows = rows;
        this.cols = cols;
        data = new double[rows*cols];
    }

    Matrix(double[][] d) {
        this.rows = d.length;
        int max = 0;
        for (int i = 0; i < rows; i++) {
            int len = d[i].length;
            if (len > max) max = len;
        }
        this.cols = max;
        data = new double[rows*cols];

        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                if (j < d[i].length) {
                    data[i*cols + j] = d[i][j];
                }
                else {
                    data[i*cols + j] = 0;
                }
            }
        }
    }

    double[][] asArray() {
        double[][] returnArray = new double[rows][cols];
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                returnArray[i][j] = data[i*cols + j];
            }
        }
        return returnArray;
    }

    double get(int r, int c) {
        return data[r*cols + c];
    }

    void set(int r, int c, double value) {
        data[r*cols + c] = value;
    }

    public String toString(){
        StringBuilder buf = new StringBuilder();
        buf.append("[");
        for(int i=0; i<rows; i++) {
            buf.append("[");
            for (int j = 0; j < cols; j++) {
                buf.append(Double.toString(data[i * cols + j]));

                if (j + 1 < cols) buf.append(", ");
                else buf.append("]");
            }
            if (i + 1 < rows) buf.append(", ");
        }
        buf.append("]");
        return buf.toString();
    }

    void reshape(int newRows,int newCols){
        if(rows*cols != newRows*newCols)
            throw new RuntimeException(String.format("%d x %d matrix can't be reshaped to %d x %d",rows,cols,newRows,newCols));
        else {
            this.rows = newRows;
            this.cols = newCols;
        }
    }

    int[] shape(){
        int [] tab = new int[2];
        tab[0] = rows;
        tab[1] = cols;
        return tab;
    }

    Matrix add(Matrix m) {
        if(rows != m.rows && cols != m.cols)
            throw new RuntimeException(String.format("Matrixes have different shapes"));
        else {
            Matrix temp = new Matrix(rows, cols);
            for (int i = 0; i < rows; i++) {
                for (int j = 0; j < cols; j++) {
                    temp.data[i * cols + j] = this.get(i, j) + m.get(i, j);
                }
            }
            return temp;
        }
    }

    Matrix sub(Matrix m) {
        if(rows != m.rows && cols != m.cols)
            throw new RuntimeException(String.format("Matrixes have different shapes"));
        else {
            Matrix temp = new Matrix(rows, cols);
            for (int i = 0; i < rows; i++) {
                for (int j = 0; j < cols; j++) {
                    temp.data[i * cols + j] = this.get(i, j) - m.get(i, j);
                }
            }
            return temp;
        }
    }

    Matrix mul(Matrix m) {
        if(rows != m.rows && cols != m.cols)
            throw new RuntimeException(String.format("Matrixes have different shapes"));
        else {
            Matrix temp = new Matrix(rows, cols);
            for (int i = 0; i < rows; i++) {
                for (int j = 0; j < cols; j++) {
                    temp.data[i * cols + j] = this.get(i, j) * m.get(i, j);
                }
            }
            return temp;
        }
    }

    Matrix div(Matrix m) {
        if(rows != m.rows && cols != m.cols)
            throw new RuntimeException(String.format("Matrixes have different shapes"));
        else {
            Matrix temp = new Matrix(rows, cols);
            for (int i = 0; i < rows; i++) {
                for (int j = 0; j < cols; j++) {
                    temp.data[i * cols + j] = this.get(i, j) / m.get(i, j);
                }
            }
            return temp;
        }
    }

    Matrix add(double w) {
        for (int i = 0; i < rows*cols; i++) this.data[i] += w;
        return this;
    }

    Matrix sub(double w) {
        for (int i = 0; i < rows*cols; i++) this.data[i] -= w;
        return this;
    }

    Matrix mul(double w) {
        for (int i = 0; i < rows*cols; i++) this.data[i] *= w;
        return this;
    }

    Matrix div(double w) {
        for (int i = 0; i < rows*cols; i++) this.data[i] /= w;
        return this;
    }


    public static void main(String[] args) {
        double[][] d = {
            {1,2,3},
            {4,5},
            {6},
            {40,50,60},
        };

        Matrix m = new Matrix(d);
        //double[][] array = m.asArray();

        // TESTY
        System.out.println(m.get(2,2));
        m.set(2,2, 15.5);
        System.out.println(m.get(2,2));

        String s = m.toString();
        System.out.println(s);

        int [] shape = m.shape();
        System.out.printf("Macierz ma wymiary %d x %d\n", shape[0], shape[1]);

        m.reshape(2,6);
        String s2 = m.toString();
        System.out.println(s2);

        shape = m.shape();
        System.out.printf("Macierz ma wymiary %d x %d\n", shape[0], shape[1]);

        double[][] t = {
            {1,2},
            {3,4},
        };

        Matrix d1 = new Matrix(t);
        Matrix d2 = new Matrix(t);

        int skalar = 5;

        System.out.println("\nDodawanie macierzy:");
        Matrix result1 = d1.add(d2);
        s = result1.toString();
        System.out.println(s);

        System.out.println("\nOdejmowanie macierzy:");
        Matrix result2 = d1.sub(d2);
        s = result2.toString();
        System.out.println(s);

        System.out.println("\nMnożenie elementów macierzy:");
        Matrix result3 = d1.mul(d2);
        s = result3.toString();
        System.out.println(s);

        System.out.println("\nDzielenie elementów macierzy:");
        Matrix result4 = d1.div(d2);
        s = result4.toString();
        System.out.println(s);

        System.out.printf("\nDodawanie skalara %d do macierzy:\n", skalar);
        Matrix m5 = new Matrix(t);
        Matrix result5 = m5.add(skalar);
        s = result5.toString();
        System.out.println(s);

        System.out.printf("\nOdejmowanie skalara %d od macierzy:\n", skalar);
        Matrix m6 = new Matrix(t);
        Matrix result6 = m6.sub(skalar);
        s = result6.toString();
        System.out.println(s);

        System.out.printf("\nMnożenie elementów macierzy przez skalar %d:\n", skalar);
        Matrix m7 = new Matrix(t);
        Matrix result7 = m7.mul(skalar);
        s = result7.toString();
        System.out.println(s);

        System.out.printf("\nDzielenie elementów macierzy przez skalar %d:\n", skalar);
        Matrix m8 = new Matrix(t);
        Matrix result8 = m8.div(skalar);
        s = result8.toString();
        System.out.println(s);

    }
}