mathjs/test/unit-tests/function/matrix/reshape.test.js

import assert from 'assert'
import math from '../../../../src/defaultInstance.js'
import { DimensionError } from '../../../../src/error/DimensionError.js'

describe('reshape', function () {
  it('should reshape an array', function () {
    const array = [[0, 1, 2], [3, 4, 5]]
    assert.deepStrictEqual(math.reshape(array, [3, 2]), [[0, 1], [2, 3], [4, 5]])
  })

  it('should reshape an array with bignumbers', function () {
    const zero = math.bignumber(0)
    const one = math.bignumber(1)
    const two = math.bignumber(2)
    const three = math.bignumber(3)
    const array = [zero, one, two, three]
    assert.deepStrictEqual(math.reshape(array, [two, two]),
      [[zero, one], [two, three]])
  })

  it('should reshape a matrix', function () {
    const matrix = math.matrix([[0, 1, 2], [3, 4, 5]])
    assert.deepStrictEqual(math.reshape(matrix, [3, 2]),
      math.matrix([[0, 1], [2, 3], [4, 5]]))
    assert.deepStrictEqual(math.reshape(matrix, math.matrix([3, 2])),
      math.matrix([[0, 1], [2, 3], [4, 5]]))
  })

  it('should reshape a flat single-element array into multiple dimensions', function () {
    const array = [3]
    assert.deepStrictEqual(math.reshape(array, [1, 1, 1]), [[[3]]])
  })

  it('should reshape a vector into a 2d matrix', function () {
    const math2 = math.create({ matrix: 'Array' })
    assert.deepStrictEqual(math2.reshape([1, 2, 3, 4, 5, 6], [3, 2]), [[1, 2], [3, 4], [5, 6]])
  })

  it('should reshape 2d matrix into a vector', function () {
    const math2 = math.create({ matrix: 'Array' })
    assert.deepStrictEqual(math2.reshape([[1, 2], [3, 4], [5, 6]], [6]), [1, 2, 3, 4, 5, 6])
  })

  it('should throw an error on invalid arguments', function () {
    assert.throws(function () { math.reshape() }, /Too few arguments/)
    assert.throws(function () { math.reshape([]) }, /Too few arguments/)
    assert.throws(function () { math.reshape([], 2) }, TypeError)
    assert.throws(function () { math.reshape([], [], 4) }, /Too many arguments/)

    assert.throws(function () { math.reshape([], ['no number']) }, /Cannot convert/)
    assert.throws(function () { math.reshape([], [2.3]) }, /Invalid size/)

    assert.throws(function () { math.reshape([1, 2], []) }, DimensionError)
    assert.throws(function () { math.reshape([1, 2], [0]) }, DimensionError)
    assert.throws(function () { math.reshape([1, 2], [0, 0]) }, DimensionError)
    assert.throws(function () { math.reshape([[1, 2]], [0]) }, DimensionError)
    assert.doesNotThrow(function () { math.reshape([[1, 2]], [2, 1]) })
    assert.doesNotThrow(function () { math.reshape([[1, 2]], [2]) })
  })

  it('should LaTeX reshape', function () {
    const expression = math.parse('reshape([1,2],1)')
    assert.strictEqual(expression.toTex(), '\\mathrm{reshape}\\left(\\begin{bmatrix}1\\\\2\\\\\\end{bmatrix},1\\right)')
  })

  it('should reshape a SparseMatrix', function () {
    /*
     * Must use toArray because SparseMatrix.reshape currently does not preserve
     * the order of the _index and _values arrays (this does not matter?)
     */

    let matrix = math.matrix([[0, 1, 2], [3, 4, 5]], 'sparse')
    assert.deepStrictEqual(math.reshape(matrix, [3, 2]).toArray(),
      [[0, 1], [2, 3], [4, 5]])

    assert.deepStrictEqual(math.reshape(matrix, [6, 1]).toArray(),
      [[0], [1], [2], [3], [4], [5]])

    assert.deepStrictEqual(math.reshape(matrix, [1, 6]).toArray(),
      [[0, 1, 2, 3, 4, 5]])

    matrix = math.matrix([[0, 1, 2, 3, 4, 5]], 'sparse')
    assert.deepStrictEqual(math.reshape(matrix, [3, 2]).toArray(),
      [[0, 1], [2, 3], [4, 5]])

    matrix = math.matrix([[0], [1], [2], [3], [4], [5]], 'sparse')
    assert.deepStrictEqual(math.reshape(matrix, [3, 2]).toArray(),
      [[0, 1], [2, 3], [4, 5]])
  })

  it('should throw on attempting to reshape an ImmutableDenseMatrix', function () {
    const immutableMatrix = new math.ImmutableDenseMatrix([[1, 2], [3, 4]])
    assert.throws(function () { math.reshape(immutableMatrix, [1, 4]) },
      /Cannot invoke reshape on an Immutable Matrix instance/)
  })

  it('should throw on attempting to reshape a Matrix (abstract type)', function () {
    const matrix = new math.Matrix([[1, 2], [3, 4]])
    assert.throws(function () { math.reshape(matrix, [1, 4]) },
      /Cannot invoke reshape on a Matrix interface/)
  })
})