Published unlisted
Edited
Jun 28, 2020
check_quantileIndexWithQuantile = {
const a = qi.median;
const b = d3.quantile(testArray.array, quantile);
if (a === b) {
return html `check match with d3.quantile: <br><span style="background:lightgreen";>correct ${a} (quantileIndex.median) <br>${b} (d3.quantile)</span>`;
} else { return html `check match with d3.quantile: <span style="background:IndianRed";>wrong ${a} (quantileIndex.median)<br>${b} (d3.quantile)</span>`;
}
}
d3.quantile(testArray.array, quantile)
qi = {
return quantileIndex(testArray.array, quantile)
}
testArray = {
let ar = [];
let res = {};
for (let i = 0; i < 99; i++){
ar.push(Math.random());
}
ar.sort();
res.value0 = ar[Math.floor((ar.length - 1) * quantile)];
res.value1 = ar[Math.ceil((ar.length - 1) * quantile)] ;
res.median = (ar[Math.ceil((ar.length - 1) * quantile)] + ar[Math.floor((ar.length - 1) * quantile)]) * .5;
res.array = shuffle(ar);
res.index0 = ar.indexOf(res.value0);
res.index1 = ar.indexOf(res.value1);
return res;
}
values = [20, 30, 10, -2, -10, 0]
quantileIndex(values, 0.5)
function quantileIndex(values, p, valueof) {
var n,
mix = 0,
index0,
index1;
values = valueof
? Float64Array.from(values, valueof)
: Float64Array.from(values);
const value = i => values[i],
indices = Int32Array.from({ length: values.length }, (_, i) => i);
console.log(indices);
if (!(n = values.length)) return;
if ((p = +p) <= 0 || n < 2) {
index0 = index1 = d3.minIndex(values);
} else if (p >= 1) {
index0 = index1 = d3.maxIndex(values);
} else {
let i = (n - 1) * p,
i0 = Math.floor(i);
const indices0 = d3
.quickselect(indices, i0, 0, n - 1, (i, j) =>
d3.ascending(value(i), value(j))
)
.subarray(0, i0 + 1);
index0 = indices0[d3.maxIndex(indices0, value)];
const indices1 = indices.subarray(i0 + 1);
index1 = indices1[d3.minIndex(indices1, value)];
mix = i - i0;
}
const value0 = values[index0],
value1 = values[index1],
median = mix ? (value0 + value1) / 2 : value0;
return { index0, index1, value0, value1, median, indices };
}
quantileIndex2(values, 0.5)
function quantileIndex2(values, p, valueof) {
if (valueof) values = values.map((d, i) => valueof(d, i, values));
const m = d3.quantile(values, p);
let index0,
index1,
value0 = -Infinity,
value1 = Infinity;
for (let i = 0; i < values.length; i++) {
const x = values[i];
if (x <= m) {
if (x > value0) (index0 = i), (value0 = x);
} else {
if (x < value1) (index1 = i), (value1 = x);
}
}
return { index0, index1: m === value0 ? index0 : index1, value0, value1, m };
}
quantileIndex2([0,0,0], 0.5)
d3 = require("d3-array@2")
huge = Float64Array.from({ length: 1e6 }, Math.random)
function evaluate(f) {
const t = performance.now();
const r = f(huge, 0.5);
r.t = performance.now() - t;
return r;
}
evaluate(quantileIndex)
evaluate(quantileIndex2)
evaluate(d => ({ m: d3.quantile(huge, 0.5) }))
evaluate(d => ({ m: quantileIndex(huge, 0.5).median }))
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