feat(grid-iterators): add zigzagDiagonal(), update readme, rename files

thi-ng · Oct 26, 2019 · 5630055 · 5630055
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diff --git a/assets/grid-iterators/zigzagDiagonal2d-small.gif b/assets/grid-iterators/zigzagDiagonal2d-small.gif
diff --git a/packages/grid-iterators/README.md b/packages/grid-iterators/README.md
@@ -18,6 +18,7 @@ This project is part of the
     - [Outward spiral](#outward-spiral)
     - [Z-curve](#z-curve)
     - [Zigzag columns](#zigzag-columns)
+    - [Zigzag diagonal](#zigzag-diagonal)
     - [Zigzag rows](#zigzag-rows)
 - [Installation](#installation)
 - [Dependencies](#dependencies)
@@ -29,7 +30,7 @@ This project is part of the
 
 ## About
 
-Collection of 2D grid iterators, providing the following orderings:
+Collection of 2D grid iterators, providing the 10 following orderings:
 
 ### Diagonal
 
@@ -49,18 +50,25 @@ Collection of 2D grid iterators, providing the following orderings:
 
 [Source](https://github.com/thi-ng/umbrella/tree/develop/packages/grid-iterators/src/interleave.ts)
 
+Supports custom strides... example uses `step = 4`
+
 ### Interleave rows
 
 ![anim](https://raw.githubusercontent.com/thi-ng/umbrella/develop/assets/grid-iterators/interleaverows2d-small.gif)
 
 [Source](https://github.com/thi-ng/umbrella/tree/develop/packages/grid-iterators/src/interleave.ts)
 
+Supports custom strides... example uses `step = 4`
+
 ### Random
 
 ![anim](https://raw.githubusercontent.com/thi-ng/umbrella/develop/assets/grid-iterators/random2d-small.gif)
 
 [Source](https://github.com/thi-ng/umbrella/tree/develop/packages/grid-iterators/src/random.ts)
 
+Supports custom PRNG implementations via `IRandom` interface defined in
+[@thi.ng/random](https://github.com/thi-ng/umbrella/tree/master/packages/random)
+
 ### Outward spiral
 
 ![anim](https://raw.githubusercontent.com/thi-ng/umbrella/develop/assets/grid-iterators/spiral2d-small.gif)
@@ -77,13 +85,19 @@ Collection of 2D grid iterators, providing the following orderings:
 
 ![anim](https://raw.githubusercontent.com/thi-ng/umbrella/develop/assets/grid-iterators/zigzagcolumns2d-small.gif)
 
-[Source](https://github.com/thi-ng/umbrella/tree/develop/packages/grid-iterators/src/columns.ts)
+[Source](https://github.com/thi-ng/umbrella/tree/develop/packages/grid-iterators/src/zigzag-columns.ts)
+
+### Zigzag diagonal
+
+![anim](https://raw.githubusercontent.com/thi-ng/umbrella/develop/assets/grid-iterators/zigzagdiagonal2d-small.gif)
+
+[Source](https://github.com/thi-ng/umbrella/tree/develop/packages/grid-iterators/src/zigzag-diagonal.ts)
 
 ### Zigzag rows
 
 ![anim](https://raw.githubusercontent.com/thi-ng/umbrella/develop/assets/grid-iterators/zigzagrows2d-small.gif)
 
-[Source](https://github.com/thi-ng/umbrella/tree/develop/packages/grid-iterators/src/rows.ts)
+[Source](https://github.com/thi-ng/umbrella/tree/develop/packages/grid-iterators/src/zigzag-rows.ts)
 
 Some functions have been ported from [Christopher
 Kulla](https://fpsunflower.github.io/ckulla/)'s Java-based [Sunflow

diff --git a/packages/grid-iterators/src/index.ts b/packages/grid-iterators/src/index.ts
@@ -1,8 +1,9 @@
-export * from "./columns";
 export * from "./diagonal";
 export * from "./hilbert";
 export * from "./interleave";
 export * from "./random";
-export * from "./rows";
 export * from "./spiral";
 export * from "./zcurve";
+export * from "./zigzag-columns";
+export * from "./zigzag-diagonal";
+export * from "./zigzag-rows";
diff --git a/packages/grid-iterators/src/columns.ts → ...ages/grid-iterators/src/zigzag-columns.ts b/packages/grid-iterators/src/columns.ts → ...ages/grid-iterators/src/zigzag-columns.ts
diff --git a/packages/grid-iterators/src/zigzag-diagonal.ts b/packages/grid-iterators/src/zigzag-diagonal.ts
@@ -0,0 +1,37 @@
+/**
+ * Similar to `diagonal2d`, but yields 2D grid coordinates in zigzag
+ * diagonal order starting at [0,0] and using given `cols` and `rows`.
+ *
+ * @param cols
+ * @param rows
+ */
+export function* zigzagDiagonal2d(cols: number, rows = cols) {
+    const num = cols * rows - 1;
+    for (
+        let x = 0, y = 0, ny = 0, dx = -1, dy = 1, d = 0, down = true, i = 0;
+        i <= num;
+        i++
+    ) {
+        yield [x, y];
+        if (i !== num) {
+            do {
+                if (y === ny) {
+                    if (down) {
+                        y++;
+                        d++;
+                        ny = 0;
+                    } else {
+                        x++;
+                        ny = ++d;
+                    }
+                    down = !down;
+                    dx *= -1;
+                    dy *= -1;
+                } else {
+                    x += dx;
+                    y += dy;
+                }
+            } while (x >= cols || y >= rows);
+        }
+    }
+}
diff --git a/packages/grid-iterators/src/rows.ts → packages/grid-iterators/src/zigzag-rows.ts b/packages/grid-iterators/src/rows.ts → packages/grid-iterators/src/zigzag-rows.ts
diff --git a/packages/grid-iterators/tools/build-assets.js b/packages/grid-iterators/tools/build-assets.js
@@ -11,11 +11,13 @@ try {
 [
     gi.diagonal2d,
     gi.hilbert2d,
+    gi.interleaveColumns2d,
+    gi.interleaveRows2d,
     gi.random2d,
     gi.spiral2d,
     gi.zcurve2d,
     gi.zigzagColumns2d,
-    // gi.zigzagDiagonal2d,
+    gi.zigzagDiagonal2d,
     gi.zigzagRows2d
 ].forEach((fn) => {
     console.log(`generating ${fn.name}...`);