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Rand utils code cleanup #217

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Merged
dcrescim merged 1 commit into from
Apr 19, 2022
Merged

Rand utils code cleanup #217

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40 changes: 25 additions & 15 deletions src/randUtils.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -35,11 +35,14 @@ export const createRng = (seed?: number) =>
* a random integer in the range [from, until).
*/
export const randInt = (rand: () => number) => (from: int, until: int) => {
if (from >= until)
if (from >= until) {
throw new Error('randInt(rng)(from,until): from must be less than until.')

const result = (from + (until - from) * rand()) | 0
return result - +(result == until)
}
const result = Math.floor(from + (until - from) * rand())
if (result === until) {
return result - 1
}
return result
}

/**
Expand All @@ -56,18 +59,20 @@ export const lhs = (rand: () => number) => (nSamples: int, nFeatures: int) => {
const result: Float64Array[] = []

// init columns to linspace(0,1, nSamples)
for (let i = nSamples; i-- > 0; ) {
const normalizeDiv = nSamples - 1 || 1
for (let i = nSamples - 1; i >= 0; i--) {
const row = new Float64Array(nFeatures)
row.fill(i / (nSamples - 1 || 1))
row.fill(i / normalizeDiv)
result.push(row)
}

// shuffle columns independently
for (let n, i = nSamples; (n = i--) > 1; ) {
for (let i = nSamples - 1; i >= 1; i--) {
let n = i + 1
const ri = result[i]
for (let j = nFeatures; j-- > 0; ) {
const k = _randInt(0, n),
rij = ri[j]
for (let j = nFeatures - 1; j >= 0; j--) {
const k = _randInt(0, n)
const rij = ri[j]
ri[j] = result[k][j]
result[k][j] = rij
}
Expand All @@ -76,14 +81,19 @@ export const lhs = (rand: () => number) => (nSamples: int, nFeatures: int) => {
return result
}

interface Indexable<T> {
[i: number]: T
readonly length: number
}

export const shuffle =
(rand: () => number) =>
<T>(array: { readonly length: number; [i: number]: T }) => {
<T>(array: Indexable<T>) => {
const _randInt = randInt(rand)
for (let i = array.length; i > 1; ) {
const j = _randInt(0, i--),
tmp = array[i]
array[i] = array[j]
for (let i = array.length; i > 1; i--) {
const j = _randInt(0, i)
const tmp = array[i - 1]
array[i - 1] = array[j]
array[j] = tmp
}
}