@eclass/grade-scales/lib/convertToScale.ts

Módulo para calcular notas en base a una escala.

import { ScaleAttributes } from './types'
import { gradeRound } from './grades/'

type ConvertAttributes = {
  scale: ScaleAttributes
  grade: number
}

/**
 * Transforma una nota a otra según la escala de destino.
 *
 * @example
 *
 * const scale = {
 *  name: "Chile 50% (1-7, aprobación 50%, nota 4)",
 *  keyname: "Chile50",
 *  min: 1,
 *  max: 7,
 *  passingGrade: 4,
 *  passingPercentage: 50,
 *  roundType: "round",
 *  prepend: "",
 *  append: "",
 *  decimals: 1,
 *  decimalSeparator: ","
 * }
 *
 * const newScale = {
 *  name: "Porcentaje (1-100%, aprobación 60%, nota 70)",
 *  keyname: "Porcentaje_1-100_60",
 *  min: 1,
 *  max: 100,
 *  passingGrade: 70,
 *  passingPercentage: 60,
 *  roundType: "round",
 *  prepend: "",
 *  append: "%",
 *  decimals: 0,
 *  decimalSeparator: ","
 * }
 * const converted = convertToScale({ scale, grade: 4.6 }, newScale)
 */
export const convertToScale = (
  convert: ConvertAttributes,
  scale: ScaleAttributes,
): number => {
  // Redondeamos nota actual.
  const grade = gradeRound(convert.scale, convert.grade)

  // calculamos ambos rangos (antiguo y nuevo)
  const oldRange = convert.scale.max - convert.scale.min
  const newRange = scale.max - scale.min

  // transformamos la nota
  const newGrade =
    ((grade - convert.scale.min) * newRange) / oldRange + scale.min

  // redondeamos
  return gradeRound(scale, newGrade)
}