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PatrickMcSweeny's solution

to Matrix in the JavaScript Track

Published at Aug 28 2019 · 0 comments
Instructions
Test suite
Solution

Note:

This exercise has changed since this solution was written.

Given a string representing a matrix of numbers, return the rows and columns of that matrix.

So given a string with embedded newlines like:

9 8 7
5 3 2
6 6 7

representing this matrix:

    1  2  3
  |---------
1 | 9  8  7
2 | 5  3  2
3 | 6  6  7

your code should be able to spit out:

  • A list of the rows, reading each row left-to-right while moving top-to-bottom across the rows,
  • A list of the columns, reading each column top-to-bottom while moving from left-to-right.

The rows for our example matrix:

  • 9, 8, 7
  • 5, 3, 2
  • 6, 6, 7

And its columns:

  • 9, 5, 6
  • 8, 3, 6
  • 7, 2, 7

Setup

Go through the setup instructions for Javascript to install the necessary dependencies:

https://exercism.io/tracks/javascript/installation

Requirements

Install assignment dependencies:

$ npm install

Making the test suite pass

Execute the tests with:

$ npm test

In the test suites all tests but the first have been skipped.

Once you get a test passing, you can enable the next one by changing xtest to test.

Source

Warmup to the saddle-points warmup. http://jumpstartlab.com

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

matrix.spec.js

import { Matrix } from './matrix';

describe('Matrix', () => {
  test('extract row from one number matrix', () => {
    expect(new Matrix('1').rows[0]).toEqual([1]);
  });

  xtest('can extract row', () => {
    expect(new Matrix('1 2\n3 4').rows[1]).toEqual([3, 4]);
  });

  xtest('extract row where numbers have different widths', () => {
    expect(new Matrix('1 2\n10 20').rows[1]).toEqual([10, 20]);
  });

  xtest('can extract row from non-square matrix', () => {
    expect(new Matrix('1 2 3\n4 5 6\n7 8 9\n8 7 6').rows[2]).toEqual([7, 8, 9]);
  });

  xtest('extract column from one number matrix', () => {
    expect(new Matrix('1').columns[0]).toEqual([1]);
  });

  xtest('can extract column', () => {
    expect(new Matrix('1 2 3\n4 5 6\n7 8 9').columns[2]).toEqual([3, 6, 9]);
  });

  xtest('can extract column from non-square matrix', () => {
    expect(new Matrix('1 2 3\n4 5 6\n7 8 9\n8 7 6').columns[2]).toEqual([3, 6, 9, 6]);
  });

  xtest('extract column where numbers have different widths', () => {
    expect(new Matrix('89 1903 3\n18 3 1\n9 4 800').columns[1]).toEqual([1903, 3, 4]);
  });
});
export class Matrix {
  constructor(matrix) {
    this.matrixRows = matrix
      .split("\n")
      .map(row => row.split(" ").map(Number));

    this.matrixColumns = this.rows.map((col, i) =>
      this.rows.map(row => row[i])
    );
  }

  get rows() {
    return this.matrixRows;
  }

  get columns() {
    return this.matrixColumns;
  }
}

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