@thi.ng/grid-iterators
Advanced tools
This project is part of the @thi.ng/umbrella monorepo.
2D grid and shape iterators w/ multiple orderings.
Provides the altogether 25 following orderings (excluding symmetries) to generate grid coordinates, including iterators for shape rasterization, drawing, clipping, filling, processing in general:
Also see the filtered version
columnEnds2d(),
which only includes the end points of each column.
Also see the filtered version
diagonalEnds2d(),
which only includes the end points of the diagonals.
Supports custom strides... example uses step = 4
Supports custom strides... example uses step = 4
Supports custom PRNG implementations via IRandom interface defined in
@thi.ng/random
Also see the filtered version
rowEnds2d(),
which only includes the end points of each row.
Some functions have been ported from Christopher Kulla's Java-based Sunflow renderer.
For more basic 2D/3D grid iteration, also see range2d() & range3d()
in
@thi.ng/transducers.
All of the above mentioned grid iterators support point (grid coordinate)
transformations to create variations of their base orderings. The package
provides the flipX, flipY and flipXY preset transforms to mirror one or
both axes, but custom transforms can be easily implemented via the same
underlying mechanism. These transforms can be specified via the tx option
passed to the iterators (see code example further below).
The floodFill() iterator can be used to iterate arbitrary 2D grids using an
user-provided predicate function. The function recursively explores (in a
row-major manner) the space in the [0,0]..(width,height) interval, starting at
given x,y and continues as long given predicate function returns a truthy
value. Any eligible 90-degree connected regions will be found and iterated
recursively. The predicate function is used to select eligible grid cells
(e.g. "pixels" of sorts).
// source "image"
const img = [
"█", " ", " ", " ", "█",
"█", " ", "█", " ", " ",
" ", " ", "█", " ", "█",
" ", "█", "█", " ", " ",
" ", " ", " ", "█", "█",
];
// flood fill iterator from point (1,0)
// only accept " " as source pixel value
// image size is 5x5
const region = floodFill((x, y) => img[x + y * 5] === " ", 1, 0, 5, 5);
// label filled pixels using increasing ASCII values
let ascii = 65; // "A"
for(let [x,y] of region) img[x + y * 5] = String.fromCharCode(ascii++);
// result image showing fill order
img
// [
// "█", "A", "B", "C", "█",
// "█", "I", "█", "D", "E",
// "K", "J", "█", "F", "█",
// "L", "█", "█", "G", "H",
// "M", "N", "O", "█", "█"
// ]
Additionally, the following shape iterators are available, all also with optional clipping:
STABLE - used in production
Search or submit any issues for this package
yarn add @thi.ng/grid-iterators
ES module import:
<script type="module" src="https://cdn.skypack.dev/@thi.ng/grid-iterators"></script>
For Node.js REPL:
const gridIterators = await import("@thi.ng/grid-iterators");
Package sizes (brotli'd, pre-treeshake): ESM: 2.52 KB
Several demos in this repo's /examples directory are using this package.
A selection:
| Screenshot | Description | Live demo | Source |
|---|---|---|---|
 | Visualization of different grid iterator strategies | Demo | Source |
import * as gi from "@thi.ng/grid-iterators";
[...gi.zigzagRows2d({ cols: 4, rows: 4 })]
// [
// [ 0, 0 ], [ 1, 0 ], [ 2, 0 ], [ 3, 0 ],
// [ 3, 1 ], [ 2, 1 ], [ 1, 1 ], [ 0, 1 ],
// [ 0, 2 ], [ 1, 2 ], [ 2, 2 ], [ 3, 2 ],
// [ 3, 3 ], [ 2, 3 ], [ 1, 3 ], [ 0, 3 ]
// ]
// with applied horizontal mirroring
// also, if `rows` is missing, it defaults to same value as `cols`
[...gi.zigzagRows2d({ cols: 4, tx: gi.flipX })]
// [
// [ 3, 0 ], [ 2, 0 ], [ 1, 0 ], [ 0, 0 ],
// [ 0, 1 ], [ 1, 1 ], [ 2, 1 ], [ 3, 1 ],
// [ 3, 2 ], [ 2, 2 ], [ 1, 2 ], [ 0, 2 ],
// [ 0, 3 ], [ 1, 3 ], [ 2, 3 ], [ 3, 3 ]
// ]
If this project contributes to an academic publication, please cite it as:
@misc{thing-grid-iterators,
title = "@thi.ng/grid-iterators",
author = "Karsten Schmidt",
note = "https://thi.ng/grid-iterators",
year = 2019
}
© 2019 - 2023 Karsten Schmidt // Apache License 2.0
FAQs
2D grid and shape iterators w/ multiple orderings
The npm package @thi.ng/grid-iterators receives a total of 39 weekly downloads. As such, @thi.ng/grid-iterators popularity was classified as not popular.
We found that @thi.ng/grid-iterators demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
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