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// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
export type IMatrix = number[][];export type RowNumber = number;export type ColNumber = number;
export type Shape = [RowNumber, ColNumber];
function ensureMatrixSize(a: Matrix, b: Matrix) {  const [aRowSize, aColSize] = a.shape;  const [bRowSize, bColSize] = b.shape;
  if (aRowSize !== bRowSize || aColSize !== bColSize) {    throw new Error("Matrices must be the same size.");  }}
export class Matrix {  constructor(public matrix: IMatrix) {    const colLength = (matrix[0] || []).length;    const isValidcolLength = matrix.every(row => row.length === colLength);    if (!isValidcolLength) {      throw new Error("Not available matrix.");    }  }  /**   * Get the size of Matrix   */  public get shape(): Shape {    const elementSize = this.matrix[0].length;    const rowSize = this.matrix.length;    return [rowSize, elementSize];  }  private generateNewShape(shape: Shape) {    const [rowNumber, colNumber] = shape;    const [originRowNumber, originColNumber] = this.shape;
    if (rowNumber * colNumber !== originRowNumber * originColNumber) {      throw new Error(        `Can not change the shape from (${originRowNumber}, ${originColNumber}) to (${rowNumber}, ${colNumber})`      );    }
    const output: IMatrix = [];    const origin = this.matrix.flat();
    for (let i = 0; i < rowNumber; i++) {      let row: number[] = [];      while (row.length !== colNumber) {        row = row.concat(origin.splice(0, colNumber));      }      output.push(row);    }
    return output;  }  /**   * Change the size of Matrix   */  public set shape(shape: Shape) {    this.matrix = this.generateNewShape(shape);  }  /**   * Generate the new size of Matrix   */  public reshape(shape: Shape): Matrix {    return new Matrix(this.generateNewShape(shape));  }  /**   * Multiply the matrix by a number or matrix. similar like `a * b`   * @param n a number or matrix   */  public times(n: number | Matrix) {    if (n instanceof Matrix) {      const output = [];      for (let i = 0; i < this.matrix.length; i++) {        const row = this.matrix[i];        const newRow = [];
        const [_, colSize] = n.shape;
        for (let i = 0; i < colSize; i++) {          const row2 = n.matrix.map(v => v[i]);          const c = row            .map((v, index) => v * row2[index])            .reduce((a, b) => a + b, 0);
          newRow.push(c);        }
        output.push(newRow);      }      return new Matrix(output);    } else {      const output = [];      for (const row of this.matrix) {        output.push(row.map(v => v * n));      }      return new Matrix(output);    }  }  /**   * Divided the matrix by a number or matrix. similar like `a / b`   * @param n a number or matrix   */  public div(n: number | Matrix) {    if (n instanceof Matrix) {      const output = [];      for (let i = 0; i < this.matrix.length; i++) {        const row = this.matrix[i];        const newRow = [];
        const [_, colSize] = n.shape;
        for (let i = 0; i < colSize; i++) {          const row2 = n.matrix.map(v => v[i]);          const c = row            .map((v, index) => v / row2[index])            .reduce((a, b) => a + b, 0);
          newRow.push(c);        }
        output.push(newRow);      }      return new Matrix(output);    } else {      const output = [];      for (const row of this.matrix) {        output.push(row.map(v => v / n));      }      return new Matrix(output);    }  }  /**   * Plus matrix. similar like `a + b`   * @param n a number or matrix   */  public plus(n: Matrix) {    ensureMatrixSize(this, n);    const output = [];    for (let i = 0; i < this.matrix.length; i++) {      const row = this.matrix[i];      output.push(row.map((v, m) => v + n.matrix[i][m]));    }    return new Matrix(output);  }  /**   * Plus matrix. similar like `a - b`   * @param n a number or matrix   */  public minus(n: Matrix) {    ensureMatrixSize(this, n);    const output = [];    for (let i = 0; i < this.matrix.length; i++) {      const row = this.matrix[i];      output.push(row.map((v, m) => v - n.matrix[i][m]));    }    return new Matrix(output);  }  /**   * Get the trace of the Matrix   * @param k   */  public trace(k: number = 0): number {    let tack = 0;    for (let i = 0; i < this.matrix.length; i++) {      const row = this.matrix[i];      tack += row[i + k] || 0;    }    return tack;  }  /**   * Transpose and return new Matrix   */  public transpose(): Matrix {    const output = [];    const [_, colSize] = this.shape;
    for (let i = 0; i < colSize; i++) {      output.push(this.col(i));    }
    return new Matrix(output);  }  /**   * Get the value of a row   * @param row   * @param col   */  public row(row: number): number[] {    return this.matrix[row];  }  /**   * Get the value of a col   * @param col   */  public col(col: number): number[] {    return this.matrix.map(v => v[col]);  }  /**   * Get a value of a point   * @param row   * @param col   */  public pointAt(row: number, col: number): number {    return this.matrix[row][col];  }  /**   * Print to human readable string   */  public toString(): string {    const output = [];    for (const row of this.matrix) {      output.push(row.join(", "));    }    return output.join("\n");  }  public valueOf() {    return this.matrix;  }}