@ldrick/trade-indicators/dist/movements/atr.js

Trade Indicators

import { apply as AP, either as E, function as F, option as O, readonlyArray as RA, readonlyNonEmptyArray as RNEA, } from 'fp-ts/lib';
import { smmaC } from '../averages/smma.js';
import { UnequalArraySizesError } from '../errors/UnequalArraySizesError.js';
import * as arr from '../utils/array.js';
import * as big from '../utils/big.js';
import * as num from '../utils/number.js';
import * as rec from '../utils/record.js';
const trueRange = (values) => F.pipe(values.high, arr.tail, E.chain(RNEA.traverseWithIndex(E.Applicative)((index, high) => F.pipe(O.bindTo('previousClose')(RA.lookup(index)(values.close)), O.bind('currentLow', () => RA.lookup(index + 1)(values.low)), O.map(({ previousClose, currentLow }) => big.max([
    high.sub(currentLow),
    high.sub(previousClose).abs(),
    currentLow.sub(previousClose).abs(),
])), E.fromOption(() => new UnequalArraySizesError())))));
/**
 * ATR without checks and conversion.
 *
 * @internal
 */
export const atrC = (values, period) => F.pipe(values, trueRange, E.chain((tr) => smmaC(tr, period)));
/**
 * The Average True Range (ATR) a period of the True Range Indicator,
 * being the greatest out of current high minus the current low,
 * the absolute value of current high minus previous close
 * and the absolute value of the current low minus the prevous close.
 *
 * @public
 */
export const atr = (values, period = 14) => F.pipe(AP.sequenceS(E.Applicative)({
    periodV: num.validatePositiveInteger(period),
    valuesV: rec.validateRequiredSize(period + 1)(values),
}), E.bind('valuesB', ({ valuesV }) => rec.toBig(valuesV)), E.chain(({ valuesB, periodV }) => atrC(valuesB, periodV)), E.map(arr.toNumber));