locutus
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Locutus other languages' standard libraries to JavaScript for fun and educational purposes
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JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.seq = seq;
function seq(from, to, by, length_out) {
// discuss at: https://locutus.io/r/seq/
// original by: Kevin van Zonneveld (https://kvz.io)
// note 1: Generates numeric sequences, similar to common R seq() forms.
// note 2: Supported forms: seq(to), seq(from, to), seq(from, to, by), seq(from, to, undefined, length_out).
// example 1: seq(5)
// returns 1: [1, 2, 3, 4, 5]
// example 2: seq(1, 5, 2)
// returns 2: [1, 3, 5]
// example 3: seq(1, 2, undefined, 5)
// returns 3: [1, 1.25, 1.5, 1.75, 2]
const start = Number(to === undefined ? 1 : from);
const end = Number(to === undefined ? from : to);
if (!Number.isFinite(start) || !Number.isFinite(end)) {
return [];
}
const lengthOut = normalizeLengthOut(length_out);
if (lengthOut !== null) {
if (lengthOut <= 0) {
return [];
}
if (lengthOut === 1) {
return [start];
}
const step = (end - start) / (lengthOut - 1);
const out = [];
for (let i = 0; i < lengthOut; i++) {
out.push(roundNumber(start + step * i));
}
return out;
}
const step = by === undefined ? (end >= start ? 1 : -1) : Number(by);
if (!Number.isFinite(step) || step === 0) {
throw new RangeError('seq(): by must be a non-zero finite number');
}
if ((end - start) * step < 0) {
return [];
}
const out = [];
const epsilon = Math.abs(step) * 1e-12;
if (step > 0) {
for (let value = start; value <= end + epsilon; value += step) {
out.push(roundNumber(value));
}
}
else {
for (let value = start; value >= end - epsilon; value += step) {
out.push(roundNumber(value));
}
}
return out;
}
function normalizeLengthOut(value) {
if (value === undefined) {
return null;
}
const n = Number(value);
if (!Number.isFinite(n)) {
return null;
}
return Math.trunc(n);
}
function roundNumber(value) {
return Number.parseFloat(value.toFixed(12));
}