Initialize TypeScript NumPy-style core API for vector ops

.gitignore

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+node_modules/
+dist/

README.md

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-# numpst
+# numpst
+
+A small TypeScript port of common NumPy-style vector operations.
+
+## API
+
+- `array(iterable)`
+- `zeros(length)`
+- `ones(length)`
+- `arange(start, stop?, step?)`
+- `add(a, b)`
+- `subtract(a, b)`
+- `multiply(a, b)`
+- `divide(a, b)`
+- `sum(values)`
+- `mean(values)`
+
+## Development
+
+```bash
+npm install
+npm test
+```

package.json

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+{
+  "name": "numpst",
+  "version": "1.0.0",
+  "description": "TypeScript port of NumPy",
+  "main": "dist/index.js",
+  "scripts": {
+    "test": "npm run build && node --test test",
+    "build": "tsc"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "devDependencies": {
+    "typescript": "^6.0.3"
+  },
+  "types": "dist/index.d.ts"
+}

src/index.ts

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+export type VectorLike = number[];
+
+const assertSameLength = (a: VectorLike, b: VectorLike): void => {
+  if (a.length !== b.length) {
+    throw new Error(`Shape mismatch: ${a.length} !== ${b.length}`);
+  }
+};
+
+export const array = (values: Iterable<number>): number[] => [...values];
+
+export const zeros = (length: number): number[] => {
+  if (!Number.isInteger(length) || length < 0) {
+    throw new Error("length must be a non-negative integer");
+  }
+  return new Array<number>(length).fill(0);
+};
+
+export const ones = (length: number): number[] => {
+  if (!Number.isInteger(length) || length < 0) {
+    throw new Error("length must be a non-negative integer");
+  }
+  return new Array<number>(length).fill(1);
+};
+
+export const arange = (start: number, stop?: number, step = 1): number[] => {
+  if (step === 0) {
+    throw new Error("step must not be zero");
+  }
+
+  const from = stop === undefined ? 0 : start;
+  const to = stop === undefined ? start : stop;
+  const out: number[] = [];
+
+  if (step > 0) {
+    for (let i = from; i < to; i += step) {
+      out.push(i);
+    }
+  } else {
+    for (let i = from; i > to; i += step) {
+      out.push(i);
+    }
+  }
+
+  return out;
+};
+
+const elementwise = (
+  a: VectorLike,
+  b: VectorLike,
+  op: (left: number, right: number) => number,
+): number[] => {
+  assertSameLength(a, b);
+  return a.map((value, idx) => op(value, b[idx]!));
+};
+
+export const add = (a: VectorLike, b: VectorLike): number[] =>
+  elementwise(a, b, (left, right) => left + right);
+
+export const subtract = (a: VectorLike, b: VectorLike): number[] =>
+  elementwise(a, b, (left, right) => left - right);
+
+export const multiply = (a: VectorLike, b: VectorLike): number[] =>
+  elementwise(a, b, (left, right) => left * right);
+
+export const divide = (a: VectorLike, b: VectorLike): number[] =>
+  elementwise(a, b, (left, right) => left / right);
+
+export const sum = (values: VectorLike): number =>
+  values.reduce((acc, current) => acc + current, 0);
+
+export const mean = (values: VectorLike): number => {
+  if (values.length === 0) {
+    throw new Error("cannot compute mean of empty array");
+  }
+
+  return sum(values) / values.length;
+};

test/numpst.test.js

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+const test = require('node:test');
+const assert = require('node:assert/strict');
+const np = require('../dist/index.js');
+
+test('array construction helpers', () => {
+  assert.deepEqual(np.array([1, 2, 3]), [1, 2, 3]);
+  assert.deepEqual(np.zeros(3), [0, 0, 0]);
+  assert.deepEqual(np.ones(2), [1, 1]);
+  assert.deepEqual(np.arange(4), [0, 1, 2, 3]);
+  assert.deepEqual(np.arange(1, 6, 2), [1, 3, 5]);
+});
+
+test('vector arithmetic', () => {
+  const a = [1, 2, 3];
+  const b = [4, 5, 6];
+  assert.deepEqual(np.add(a, b), [5, 7, 9]);
+  assert.deepEqual(np.subtract(b, a), [3, 3, 3]);
+  assert.deepEqual(np.multiply(a, b), [4, 10, 18]);
+  assert.deepEqual(np.divide(b, a), [4, 2.5, 2]);
+});
+
+test('reductions', () => {
+  assert.equal(np.sum([1, 2, 3, 4]), 10);
+  assert.equal(np.mean([1, 2, 3, 4]), 2.5);
+});

tsconfig.json

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+{
+  // Visit https://aka.ms/tsconfig to read more about this file
+  "compilerOptions": {
+    // File Layout
+    "rootDir": "src",
+    "outDir": "dist",
+
+    // Environment Settings
+    // See also https://aka.ms/tsconfig/module
+    "module": "commonjs",
+    "target": "es2020",
+    "types": [],
+    // For nodejs:
+    // "lib": ["esnext"],
+    // "types": ["node"],
+    // and npm install -D @types/node
+
+    // Other Outputs
+    "sourceMap": true,
+    "declaration": true,
+    "declarationMap": true,
+
+    // Stricter Typechecking Options
+    "noUncheckedIndexedAccess": true,
+    "exactOptionalPropertyTypes": true,
+
+    // Style Options
+    // "noImplicitReturns": true,
+    // "noImplicitOverride": true,
+    // "noUnusedLocals": true,
+    // "noUnusedParameters": true,
+    // "noFallthroughCasesInSwitch": true,
+    // "noPropertyAccessFromIndexSignature": true,
+
+    // Recommended Options
+    "strict": true,
+    "jsx": "react-jsx",
+    "verbatimModuleSyntax": false,
+    "isolatedModules": true,
+    "noUncheckedSideEffectImports": true,
+    "moduleDetection": "force",
+    "skipLibCheck": true,
+
+    "esModuleInterop": true,
+  }
+}