feat(grid-iterators): add diagonalSlopeX/Y()

- add diagonal iterators with configurable slope (X & Y versions)
- update pkg deps

packages/grid-iterators/package.json

@@ -39,6 +39,7 @@
 		"@thi.ng/arrays": "^2.5.8",
 		"@thi.ng/binary": "^3.3.21",
 		"@thi.ng/bitfield": "^2.2.24",
+		"@thi.ng/errors": "^2.2.13",
 		"@thi.ng/morton": "^3.1.32",
 		"@thi.ng/random": "^3.3.27",
 		"@thi.ng/transducers": "^8.4.0"
@@ -101,6 +102,9 @@
 		"./diagonal-ends": {
 			"default": "./diagonal-ends.js"
 		},
+		"./diagonal-slope": {
+			"default": "./diagonal-slope.js"
+		},
 		"./diagonal": {
 			"default": "./diagonal.js"
 		},

packages/grid-iterators/src/diagonal-slope.ts

@@ -0,0 +1,104 @@
+import { assert } from "@thi.ng/errors/assert";
+import type { GridIterOpts } from "./api.js";
+import { __opts } from "./utils.js";
+
+/**
+ * Similar to {@link diagonalSlopeX}. Yields sequence of 2D grid coordinates in
+ * diagonal order with configurable slope, starting at [0,0]. Each diagonal
+ * starts at y=0 and progresses in +y direction and every `slope` steps, one
+ * step in -x direction.
+ *
+ * @example
+ * ```ts
+ * // iterate grid in diagonals of 1:3 ratio (x:y)
+ * [...diagonalSlopeY({ cols: 5, slope: 3 })]
+ * // [
+ * //   [0, 0], [0, 1 ], [0, 2 ],
+ * //   [1, 0], [1, 1 ], [1, 2 ],
+ * //   [0, 3], [0, 4 ], [2, 0 ],
+ * //   [2, 1], [2, 2 ], [1, 3 ],
+ * //   [1, 4], [3, 0 ], [3, 1 ],
+ * //   [3, 2], [2, 3 ], [2, 4 ],
+ * //   [4, 0], [4, 1 ], [4, 2 ],
+ * //   [3, 3], [3, 4 ], [4, 3 ],
+ * //   [4, 4]
+ * // ]
+ * ```
+ *
+ * @param opts -
+ */
+export function* diagonalSlopeY(opts: GridIterOpts & { slope: number }) {
+	const { cols, rows, tx } = __opts(opts);
+	const maxX = cols - 1;
+	const slope = opts.slope | 0;
+	assert(slope > 0, "slope must be > 0");
+	const num = cols * rows - 1;
+	let x = 0;
+	let y = 0;
+	let nx = Math.min(1, maxX);
+	let ny = nx > 0 ? 0 : slope;
+	let n = slope;
+	const reset = () => {
+		n = slope;
+		x = nx;
+		y = ny;
+		if (nx < maxX) nx++;
+		else ny += slope;
+	};
+	for (let i = 0; i <= num; i++) {
+		yield tx(x, y);
+		if (--n > 0) {
+			y++;
+			if (y >= rows) reset();
+		} else {
+			x--;
+			y++;
+			if (x < 0 || y >= rows) reset();
+			else n = slope;
+		}
+	}
+}
+
+/**
+ * Similar to {@link diagonalSlopeY}. Yields sequence of 2D grid coordinates in
+ * diagonal order with configurable slope, starting at [slope-1,0]. Each
+ * diagonal starts at y=0 and progresses in -x direction and every `slope`
+ * steps, one step in +y direction.
+ *
+ * @param opts -
+ */
+export function* diagonalSlopeX(opts: GridIterOpts & { slope: number }) {
+	const { cols, rows, tx } = __opts(opts);
+	const maxX = cols - 1;
+	const slope = opts.slope | 0;
+	assert(slope > 0, "slope must be > 0");
+	const num = cols * rows - 1;
+	let x = Math.min(slope - 1, maxX);
+	let y = 0;
+	let n = x + 1;
+	let nx = Math.min(x + slope, maxX);
+	let ny = nx > 0 ? 0 : slope;
+	const reset = () => {
+		x = nx;
+		y = ny;
+		if (nx < maxX) {
+			nx = Math.min(nx + slope, maxX);
+			n = slope;
+		} else {
+			ny++;
+			n = (x % slope) + 1;
+		}
+	};
+	for (let i = 0; i <= num; i++) {
+		yield tx(x, y);
+		if (--n > 0) {
+			x--;
+			if (x < 0) reset();
+		} else {
+			x--;
+			y++;
+			if (x < 0 || y >= rows) reset();
+			else n = slope;
+		}
+	}
+}

packages/grid-iterators/src/index.ts

@@ -5,6 +5,7 @@ export * from "./column-ends.js";
 export * from "./columns.js";
 export * from "./diagonal.js";
 export * from "./diagonal-ends.js";
+export * from "./diagonal-slope.js";
 export * from "./diamond-square.js";
 export * from "./flood-fill.js";
 export * from "./hilbert.js";

yarn.lock

@@ -3802,6 +3802,7 @@ __metadata:
     "@thi.ng/arrays": ^2.5.8
     "@thi.ng/binary": ^3.3.21
     "@thi.ng/bitfield": ^2.2.24
+    "@thi.ng/errors": ^2.2.13
     "@thi.ng/morton": ^3.1.32
     "@thi.ng/random": ^3.3.27
     "@thi.ng/testament": ^0.3.13