mathjs/src/function/matrix/resize.js

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser with support for symbolic computation, comes with a large set of built-in functions and constants, and offers an integrated solution to work with dif

'use strict'

const DimensionError = require('../../error/DimensionError')
const ArgumentsError = require('../../error/ArgumentsError')

const isInteger = require('../../utils/number').isInteger
const format = require('../../utils/string').format
const clone = require('../../utils/object').clone
const array = require('../../utils/array')

function factory (type, config, load, typed) {
  const matrix = load(require('../../type/matrix/function/matrix'))

  /**
   * Resize a matrix
   *
   * Syntax:
   *
   *     math.resize(x, size)
   *     math.resize(x, size, defaultValue)
   *
   * Examples:
   *
   *     math.resize([1, 2, 3, 4, 5], [3]) // returns Array  [1, 2, 3]
   *     math.resize([1, 2, 3], [5], 0)    // returns Array  [1, 2, 3, 0, 0]
   *     math.resize(2, [2, 3], 0)         // returns Matrix [[2, 0, 0], [0, 0, 0]]
   *     math.resize("hello", [8], "!")    // returns string 'hello!!!'
   *
   * See also:
   *
   *     size, squeeze, subset, reshape
   *
   * @param {Array | Matrix | *} x             Matrix to be resized
   * @param {Array | Matrix} size              One dimensional array with numbers
   * @param {number | string} [defaultValue=0] Zero by default, except in
   *                                           case of a string, in that case
   *                                           defaultValue = ' '
   * @return {* | Array | Matrix} A resized clone of matrix `x`
   */
  // TODO: rework resize to a typed-function
  const resize = function resize (x, size, defaultValue) {
    if (arguments.length !== 2 && arguments.length !== 3) {
      throw new ArgumentsError('resize', arguments.length, 2, 3)
    }

    if (type.isMatrix(size)) {
      size = size.valueOf() // get Array
    }

    if (type.isBigNumber(size[0])) {
      // convert bignumbers to numbers
      size = size.map(function (value) {
        return type.isBigNumber(value) ? value.toNumber() : value
      })
    }

    // check x is a Matrix
    if (type.isMatrix(x)) {
      // use optimized matrix implementation, return copy
      return x.resize(size, defaultValue, true)
    }

    if (typeof x === 'string') {
      // resize string
      return _resizeString(x, size, defaultValue)
    }

    // check result should be a matrix
    const asMatrix = Array.isArray(x) ? false : (config.matrix !== 'Array')

    if (size.length === 0) {
      // output a scalar
      while (Array.isArray(x)) {
        x = x[0]
      }

      return clone(x)
    } else {
      // output an array/matrix
      if (!Array.isArray(x)) {
        x = [x]
      }
      x = clone(x)

      const res = array.resize(x, size, defaultValue)
      return asMatrix ? matrix(res) : res
    }
  }

  resize.toTex = undefined // use default template

  return resize

  /**
   * Resize a string
   * @param {string} str
   * @param {number[]} size
   * @param {string} [defaultChar=' ']
   * @private
   */
  function _resizeString (str, size, defaultChar) {
    if (defaultChar !== undefined) {
      if (typeof defaultChar !== 'string' || defaultChar.length !== 1) {
        throw new TypeError('Single character expected as defaultValue')
      }
    } else {
      defaultChar = ' '
    }

    if (size.length !== 1) {
      throw new DimensionError(size.length, 1)
    }
    const len = size[0]
    if (typeof len !== 'number' || !isInteger(len)) {
      throw new TypeError('Invalid size, must contain positive integers ' +
          '(size: ' + format(size) + ')')
    }

    if (str.length > len) {
      return str.substring(0, len)
    } else if (str.length < len) {
      let res = str
      for (let i = 0, ii = len - str.length; i < ii; i++) {
        res += defaultChar
      }
      return res
    } else {
      return str
    }
  }
}

exports.name = 'resize'
exports.factory = factory