pylylabel 4.0.0

A Rust implementation of the Polylabel algorithm for finding optimum polygon label positions, with Python binding.

Pylylabel

A Rust implementation of the Polylabel algorithm.

This is a fork of polylabel-rs. Pylylabel's polylabel function also returns the distance from the label position to the polygon. Python binding is provided using PyO3.

The orange dot is the polygon centroid. The teal dot is the ideal label position. Red boxes show the search space.

How to Use

extern crate pylylabel;
use pylylabel::polylabel;

extern crate geo;
use geo::{Point, Polygon};

let coords = vec![
    (0.0, 0.0),
    (4.0, 0.0),
    (4.0, 1.0),
    (1.0, 1.0),
    (1.0, 4.0),
    (0.0, 4.0),
    (0.0, 0.0)
];
let poly = Polygon::new(coords.into(), vec![]);
let label_pos, distance = polylabel(&poly, &0.10);
// Point(0.5625, 0.5625), 0.5625

from pylylabel import polylabel
from shapely.geometry import Polygon

exterior = [
    [0.0, 0.0],
    [4.0, 0.0],
    [4.0, 1.0],
    [1.0, 1.0],
    [1.0, 4.0],
    [0.0, 4.0],
    [0.0, 0.0]
]
pol = Polygon(exterior)
x, y, distance = polylabel(pol, tolerance=0.1)
# 0.5625, 0.5625, 0.5625

Documentation

https://docs.rs/polylabel

Performance vs Accuracy

Using a 4-core 2.3 GHz Intel Core i5, finding a label position on a ~9k-vertex polygon (representing the Norwegian mainland) using a tolerance of 1.0 takes around 9 ms. Depending upon the dimensions of your polygon(s), you may require a higher tolerance (i.e. a smaller number). See here for some guidance on the accuracy provided by each decimal place.

Build

Requirements:

• Python 3.5+
• Rust stable
• maturin

maturin build --release

License

MIT