refactor(transducers-stats): replace thi.ng/dcons dependency

- switch to use more lightweight & GC-friendly ringbuffer impl from thi.ng/buffers
- update the following transducers:
  - `momentum()`
  - `roc()`
  - `sma()`
- add tests

packages/transducers-stats/README.md

@@ -91,13 +91,13 @@ For Node.js REPL:
 const ts = await import("@thi.ng/transducers-stats");
 ```
 
-Package sizes (brotli'd, pre-treeshake): ESM: 1.75 KB
+Package sizes (brotli'd, pre-treeshake): ESM: 1.74 KB
 
 ## Dependencies
 
 - [@thi.ng/api](https://github.com/thi-ng/umbrella/tree/develop/packages/api)
+- [@thi.ng/buffers](https://github.com/thi-ng/umbrella/tree/develop/packages/buffers)
 - [@thi.ng/checks](https://github.com/thi-ng/umbrella/tree/develop/packages/checks)
-- [@thi.ng/dcons](https://github.com/thi-ng/umbrella/tree/develop/packages/dcons)
 - [@thi.ng/errors](https://github.com/thi-ng/umbrella/tree/develop/packages/errors)
 - [@thi.ng/transducers](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers)
 

packages/transducers-stats/package.json

@@ -37,8 +37,8 @@
 	},
 	"dependencies": {
 		"@thi.ng/api": "^8.11.14",
+		"@thi.ng/buffers": "^0.1.17",
 		"@thi.ng/checks": "^3.6.16",
-		"@thi.ng/dcons": "^3.2.134",
 		"@thi.ng/errors": "^2.5.20",
 		"@thi.ng/transducers": "^9.2.10"
 	},

packages/transducers-stats/src/momentum.ts

@@ -1,4 +1,4 @@
-import { DCons } from "@thi.ng/dcons/dcons";
+import { sliding } from "@thi.ng/buffers/sliding";
 import { illegalArgs } from "@thi.ng/errors/illegal-arguments";
 import type { Reducer, Transducer } from "@thi.ng/transducers";
 import { compR } from "@thi.ng/transducers/compr";
@@ -27,14 +27,13 @@ export function momentum(period: number, src?: Iterable<number>): any {
 	period < 1 && illegalArgs("period must be >= 1");
 	return (rfn: Reducer<number, any>) => {
 		const reduce = rfn[2];
-		const window = new DCons<number>();
+		const window = sliding<number>(period);
 		return compR(rfn, (acc, x: number) => {
-			window.push(x);
-			if (window.length <= period) {
-				return acc;
+			if (window.length === period) {
+				acc = reduce(acc, x - window.read());
 			}
-			const prev = window.drop()!;
-			return reduce(acc, x - prev);
+			window.write(x);
+			return acc;
 		});
 	};
 }

packages/transducers-stats/src/roc.ts

@@ -1,4 +1,4 @@
-import { DCons } from "@thi.ng/dcons/dcons";
+import { sliding } from "@thi.ng/buffers/sliding";
 import { illegalArgs } from "@thi.ng/errors/illegal-arguments";
 import type { Reducer, Transducer } from "@thi.ng/transducers";
 import { compR } from "@thi.ng/transducers/compr";
@@ -24,17 +24,18 @@ export function roc(period: number, src?: Iterable<number>): any {
 	if (src) {
 		return iterator1(roc(period), src);
 	}
+	period |= 0;
 	period < 1 && illegalArgs("period must be >= 1");
 	return (rfn: Reducer<number, any>) => {
 		const reduce = rfn[2];
-		const window = new DCons<number>();
+		const window = sliding<number>(period);
 		return compR(rfn, (acc, x: number) => {
-			window.push(x);
-			if (window.length <= period) {
-				return acc;
+			if (window.length === period) {
+				const prev = window.read();
+				acc = reduce(acc, (x - prev) / prev);
 			}
-			const prev = window.drop()!;
-			return reduce(acc, (x - prev) / prev);
+			window.write(x);
+			return acc;
 		});
 	};
 }

packages/transducers-stats/src/sma.ts

@@ -1,4 +1,4 @@
-import { DCons } from "@thi.ng/dcons/dcons";
+import { sliding } from "@thi.ng/buffers/sliding";
 import { illegalArgs } from "@thi.ng/errors/illegal-arguments";
 import type { Reducer, Transducer } from "@thi.ng/transducers";
 import { compR } from "@thi.ng/transducers/compr";
@@ -24,17 +24,18 @@ export function sma(period: number, src?: Iterable<number>): any {
 		return iterator1(sma(period), src);
 	}
 	period |= 0;
-	period < 2 && illegalArgs("period must be >= 2");
+	period < 1 && illegalArgs("period must be >= 1");
 	return (rfn: Reducer<number, any>) => {
 		const reduce = rfn[2];
-		const window = new DCons<number>();
+		const window = sliding<number>(period);
 		let sum = 0;
 		return compR(rfn, (acc, x: number) => {
-			window.push(x);
-			const n = window.length;
+			if (window.length === period) {
+				sum -= window.read();
+			}
+			window.write(x);
 			sum += x;
-			n > period && (sum -= window.drop()!);
-			return n >= period ? reduce(acc, sum / period) : acc;
+			return window.length === period ? reduce(acc, sum / period) : acc;
 		});
 	};
 }

packages/transducers-stats/test/main.test.ts

@@ -1,5 +1,12 @@
 import { expect, test } from "bun:test";
-import { donchian, movingMaximum, movingMinimum } from "../src/index.js";
+import {
+	donchian,
+	momentum,
+	movingMaximum,
+	movingMinimum,
+	roc,
+	sma,
+} from "../src/index.js";
 
 test("movingMaxium", () => {
 	expect([...movingMaximum(3, [1, 3, 1, 1, 4, 1, 1, 2, 5, 6])]).toEqual([
@@ -25,3 +32,33 @@ test("donchian", () => {
 		[2, 6],
 	]);
 });
+
+test("momentum", () => {
+	expect(() => momentum(0)).toThrow();
+	expect([...momentum(4, [1, 2, 3, 4, 5, 6, 7, 8, 9])]).toEqual([
+		4, 4, 4, 4, 4,
+	]);
+});
+
+test("roc", () => {
+	expect(() => roc(0)).toThrow();
+	expect([...roc(4, [1, 2, 3, 4, 5, 6, 7, 8, 9])]).toEqual([
+		4 / 1,
+		4 / 2,
+		4 / 3,
+		4 / 4,
+		4 / 5,
+	]);
+});
+
+test("sma", () => {
+	expect(() => sma(0)).toThrow();
+	expect([...sma(4, [1, 2, 3, 4, 5, 6, 7, 8, 9])]).toEqual([
+		(1 + 2 + 3 + 4) / 4,
+		(2 + 3 + 4 + 5) / 4,
+		(3 + 4 + 5 + 6) / 4,
+		(4 + 5 + 6 + 7) / 4,
+		(5 + 6 + 7 + 8) / 4,
+		(6 + 7 + 8 + 9) / 4,
+	]);
+});

yarn.lock

@@ -6780,8 +6780,8 @@ __metadata:
   dependencies:
     "@microsoft/api-extractor": "npm:^7.48.0"
     "@thi.ng/api": "npm:^8.11.14"
+    "@thi.ng/buffers": "npm:^0.1.17"
     "@thi.ng/checks": "npm:^3.6.16"
-    "@thi.ng/dcons": "npm:^3.2.134"
     "@thi.ng/errors": "npm:^2.5.20"
     "@thi.ng/transducers": "npm:^9.2.10"
     esbuild: "npm:^0.24.0"