mathjs/test/function/utils/partitionSelect.test.js

var assert = require('assert');
var error = require('../../../lib/error/index');
var math = require('../../../index');
var matrix = math.matrix;
var partitionSelect = math.partitionSelect;

describe('partitionSelect', function() {

  it('should sort an array with numbers', function() {
    assert.equal(partitionSelect([5,10,1], 0), 1);
    assert.equal(partitionSelect([5,10,1], 1), 5);
    assert.equal(partitionSelect([5,10,1], 2), 10);
  });

  it('should sort an array with strings', function() {
    assert.equal(partitionSelect(['C', 'B', 'A', 'D'], 0), 'A');
    assert.equal(partitionSelect(['C', 'B', 'A', 'D'], 1), 'B');
    assert.equal(partitionSelect(['C', 'B', 'A', 'D'], 2), 'C');
    assert.equal(partitionSelect(['C', 'B', 'A', 'D'], 3), 'D');
  });

  it('should sort a Matrix', function() {
    assert.equal(partitionSelect(matrix([5,10,1]), 0), 1);
    assert.equal(partitionSelect(matrix([5,10,1]), 1), 5);
    assert.equal(partitionSelect(matrix([5,10,1]), 2), 10);
  });

  it('should sort an array in ascending order', function() {
    assert.equal(partitionSelect([5,10,1], 0, 'asc'), 1);
    assert.equal(partitionSelect([5,10,1], 1, 'asc'), 5);
    assert.equal(partitionSelect([5,10,1], 2, 'asc'), 10);
  });

  it('should sort an array in descending order', function() {
    assert.equal(partitionSelect([5,10,1], 0, 'desc'), 10);
    assert.equal(partitionSelect([5,10,1], 1, 'desc'), 5);
    assert.equal(partitionSelect([5,10,1], 2, 'desc'), 1);
  });

  it('should sort an array with a custom compare function', function() {
    function sortByLength (a, b) {
      return a.length - b.length;
    }
    assert.equal(partitionSelect(['Langdon', 'Tom', 'Sara'], 0, sortByLength), 'Tom');
    assert.equal(partitionSelect(['Langdon', 'Tom', 'Sara'], 1, sortByLength), 'Sara');
    assert.equal(partitionSelect(['Langdon', 'Tom', 'Sara'], 2, sortByLength), 'Langdon');
  });

  it('should mutate the input array, leaving it partitioned at k', function() {
    var arr = [3, 2, 4, 6, -2, 5];
    partitionSelect(arr, 3);

    for (var i = 0; i < 3; ++i) {
      assert.ok(arr[i] <= arr[3]);
    }
    assert.ok(arr[3] === 4);
    for (var i = 4; i < arr.length; ++i) {
      assert.ok(arr[3] <= arr[i]);
    }
  });

  it('should mutate the input matrix, leaving it partitioned at k', function() {
    var m = matrix([3, 2, 4, 6, -2, 5]);
    partitionSelect(m, 3);

    m.forEach(function (value, index, matrix) {
      if (index[0] < 3) {
        assert.ok(value <= 4);
      } else if (index[0] === 3) {
        assert.ok(value === 4);
      } else {
        assert.ok(value >= 4);
      }
    });
  });

  it('should throw an error if called with a multi dimensional matrix', function() {
    assert.throws(function() { partitionSelect(matrix([[1,2],[3,4]]), 2) }, /Only one dimensional matrices supported/);
  });

  it('should throw an error if called with a non-negative k, within the bounds of the array', function() {
    assert.throws(function() { partitionSelect([1], -2) }, /k must be a non-negative integer/);
    assert.throws(function() { partitionSelect([3, 2, 1], 1.2) }, /k must be a non-negative integer/);
    assert.throws(function() { partitionSelect([3, 2, 1], 3) }, /k out of bounds/);
    assert.throws(function() { partitionSelect([], 0) }, /k out of bounds/);
  });

  it('should throw an error if called with unsupported type', function() {
    assert.throws(function() { partitionSelect(2, 2) }, /TypeError: Unexpected type of argument/);
    assert.throws(function() { partitionSelect('string', 2) }, /TypeError: Unexpected type of argument/);
    assert.throws(function() { partitionSelect([1], new Date()) }, /TypeError: Unexpected type of argument/);
    assert.throws(function() { partitionSelect([1], 1, 'function') }, /Error: Compare string must be "asc" or "desc"/);
    assert.throws(function() { partitionSelect([1], 1, {}) }, /TypeError: Unexpected type of argument/);
  });

  it('should throw an error if called with invalid number of arguments', function() {
    assert.throws(function() { partitionSelect() }, /TypeError: Too few arguments/);
    assert.throws(function() { partitionSelect([]) }, /TypeError: Too few arguments/);
    assert.throws(function() { partitionSelect([], 2, 'foo', 3) }, /TypeError: Too many arguments/);
  });

  /*
  it('should LaTeX sort', function () {
    var expression = math.parse('sort([3,2,1])');
    assert.equal(expression.toTex(), '\\mathrm{sort}\\left(\\begin{bmatrix}3\\\\2\\\\1\\\\\\end{bmatrix}\\right)');
  });
  */

});