From 2e7ffcc092a5148f038bddad67bc47263ebae67d Mon Sep 17 00:00:00 2001
From: Mike Bostock <mbostock@gmail.com>
Date: Sat, 3 Dec 2022 09:06:45 -0800
Subject: [PATCH] fix #262; handle invalid calls to quantile, quickselect

---
 src/quantile.js          | 12 ++++++------
 src/quickselect.js       |  8 +++++++-
 test/quantile-test.js    |  7 +++++++
 test/quickselect-test.js | 39 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 59 insertions(+), 7 deletions(-)
 create mode 100644 test/quickselect-test.js

diff --git a/src/quantile.js b/src/quantile.js
index 163343a..61d0a4a 100644
--- a/src/quantile.js
+++ b/src/quantile.js
@@ -9,8 +9,8 @@ import greatest from "./greatest.js";
 
 export default function quantile(values, p, valueof) {
   values = Float64Array.from(numbers(values, valueof));
-  if (!(n = values.length)) return;
-  if ((p = +p) <= 0 || n < 2) return min(values);
+  if (!(n = values.length) || isNaN(p = +p)) return;
+  if (p <= 0 || n < 2) return min(values);
   if (p >= 1) return max(values);
   var n,
       i = (n - 1) * p,
@@ -21,8 +21,8 @@ export default function quantile(values, p, valueof) {
 }
 
 export function quantileSorted(values, p, valueof = number) {
-  if (!(n = values.length)) return;
-  if ((p = +p) <= 0 || n < 2) return +valueof(values[0], 0, values);
+  if (!(n = values.length) || isNaN(p = +p)) return;
+  if (p <= 0 || n < 2) return +valueof(values[0], 0, values);
   if (p >= 1) return +valueof(values[n - 1], n - 1, values);
   var n,
       i = (n - 1) * p,
@@ -34,8 +34,8 @@ export function quantileSorted(values, p, valueof = number) {
 
 export function quantileIndex(values, p, valueof) {
   values = Float64Array.from(numbers(values, valueof));
-  if (!(n = values.length)) return;
-  if ((p = +p) <= 0 || n < 2) return minIndex(values);
+  if (!(n = values.length) || isNaN(p = +p)) return;
+  if (p <= 0 || n < 2) return minIndex(values);
   if (p >= 1) return maxIndex(values);
   var n,
       i = Math.floor((n - 1) * p),
diff --git a/src/quickselect.js b/src/quickselect.js
index e4b6c84..19dbb46 100644
--- a/src/quickselect.js
+++ b/src/quickselect.js
@@ -2,7 +2,13 @@ import {ascendingDefined, compareDefined} from "./sort.js";
 
 // Based on https://github.com/mourner/quickselect
 // ISC license, Copyright 2018 Vladimir Agafonkin.
-export default function quickselect(array, k, left = 0, right = array.length - 1, compare) {
+export default function quickselect(array, k, left = 0, right = Infinity, compare) {
+  k = Math.floor(k);
+  left = Math.floor(Math.max(0, left));
+  right = Math.floor(Math.min(array.length - 1, right));
+
+  if (!(left <= k && k <= right)) return array;
+
   compare = compare === undefined ? ascendingDefined : compareDefined(compare);
 
   while (right > left) {
diff --git a/test/quantile-test.js b/test/quantile-test.js
index adebec1..f323cbd 100644
--- a/test/quantile-test.js
+++ b/test/quantile-test.js
@@ -71,6 +71,13 @@ it("quantile(array, p) returns the last value for p = 1", () => {
   assert.strictEqual(quantile(data, 1), 4);
 });
 
+it("quantile(array, p) returns undefined if p is not a number", () => {
+  assert.strictEqual(quantile([1, 2, 3]), undefined);
+  assert.strictEqual(quantile([1, 2, 3], "no"), undefined);
+  assert.strictEqual(quantile([1, 2, 3], NaN), undefined);
+  assert.strictEqual(quantile([1, 2, 3], null), 1); // +null is 0
+});
+
 it("quantile(array, p, f) observes the specified accessor", () => {
   assert.strictEqual(quantile([1, 2, 3, 4].map(box), 0.5, unbox), 2.5);
   assert.strictEqual(quantile([1, 2, 3, 4].map(box), 0, unbox), 1);
diff --git a/test/quickselect-test.js b/test/quickselect-test.js
new file mode 100644
index 0000000..d279fb3
--- /dev/null
+++ b/test/quickselect-test.js
@@ -0,0 +1,39 @@
+import assert from "assert";
+import {quickselect} from "../src/index.js";
+
+it("quickselect(array, k) does nothing if k is not a number", () => {
+  const array = [3, 1, 2];
+  assert.strictEqual(quickselect(array), array);
+  assert.deepStrictEqual(array, [3, 1, 2]);
+  assert.strictEqual(quickselect(array, NaN), array);
+  assert.deepStrictEqual(array, [3, 1, 2]);
+  assert.strictEqual(quickselect(array, "no"), array);
+  assert.deepStrictEqual(array, [3, 1, 2]);
+  assert.strictEqual(quickselect(array, undefined), array);
+  assert.deepStrictEqual(array, [3, 1, 2]);
+  assert.strictEqual(quickselect(array, null), array); // coerced to zero
+  assert.deepStrictEqual(array, [1, 2, 3]);
+});
+
+it("quickselect(array, k) does nothing if k is less than left", () => {
+  const array = [3, 1, 2];
+  assert.strictEqual(quickselect(array, -1), array);
+  assert.deepStrictEqual(array, [3, 1, 2]);
+  assert.strictEqual(quickselect(array, -0.5), array);
+  assert.deepStrictEqual(array, [3, 1, 2]);
+});
+
+it("quickselect(array, k) does nothing if k is greater than right", () => {
+  const array = [3, 1, 2];
+  assert.strictEqual(quickselect(array, 3), array);
+  assert.deepStrictEqual(array, [3, 1, 2]);
+  assert.strictEqual(quickselect(array, 3.4), array);
+  assert.deepStrictEqual(array, [3, 1, 2]);
+});
+
+it("quickselect(array, k) implicitly floors k, left, and right", () => {
+  assert.deepStrictEqual(quickselect([3, 1, 2], 0.5), [1, 2, 3]);
+  assert.deepStrictEqual(quickselect([3, 1, 2, 5, 4], 4.1), [3, 1, 2, 4, 5]);
+  assert.deepStrictEqual(quickselect([3, 1, 2], 0, 0.5), [1, 2, 3]);
+  assert.deepStrictEqual(quickselect([3, 1, 2], 0, 0, 2.5), [1, 2, 3]);
+});