Rust地理空间计算库turf的使用指南

Turf是一个用于地理空间计算的Rust库，提供了高效的地理数据处理、分析和可视化功能。它是JavaScript Turf库的Rust实现版本。

主要功能

• 地理空间计算（距离、面积、缓冲区等）
• 空间关系判断（包含、相交等）
• 几何操作（合并、裁剪、简化等）
• 坐标转换和投影
• 地理空间数据可视化

安装方法

在Cargo.toml中添加依赖：

[dependencies]
turf = "0.4"

基本使用方法

1. 创建几何对象

use turf::geometry::{Geometry, Point, LineString, Polygon};
use turf::helpers::point;

// 创建一个点
let point = point!(x: -75.343, y: 39.984);

// 创建线
let line = LineString::new(vec![
    point!(x: -75.343, y: 39.984),
    point!(x: -75.534, y: 39.123),
]);

// 创建多边形
let polygon = Polygon::new(vec![
    vec![
        point!(x: -75.343, y: 39.984),
        point!(x: -75.534, y: 39.123),
        point!(x: -75.123, y: 39.456),
        point!(x: -75.343, y: 39.984),
    ]
]);

2. 计算距离

use turf::distance::distance;

let point1 = point!(x: -75.343, y: 39.984);
let point2 = point!(x: -75.534, y: 39.123);

let distance = distance(&point1, &point2);
println!("两点之间的距离: {} 公里", distance);

3. 创建缓冲区

use turf::buffer::buffer;

let point = point!(x: -75.343, y: 39.984);
let buffered = buffer(&point, 10.0, Some("kilometers"));

4. 空间关系判断

use turf::boolean_contains::boolean_contains;
use turf::boolean_within::boolean_within;

let point = point!(x: -75.343, y: 39.984);
let polygon = Polygon::new(vec![
    vec![
        point!(x: -75.5, y: 40.0),
        point!(x: -75.5, y: 39.0),
        point!(x: -75.0, y: 39.0),
        point!(x: -75.极， y: 40.0),
        point!(x: -75.5, y: 40.0),
    ]
]);

let is_contained = boolean_contains(&polygon, &point);
let is_within = boolean_within(&point, &polygon);

5. 几何操作

use turf::bbox::bbox;
use turf::center::center;

// 计算几何体的边界框
let bbox = bbox(&polygon);

// 计算几何体的中心点
let center_point = center(&polygon);

6. 可视化（使用geo-json）

use turf::geometry::Geometry;
use turf::helpers::feature_collection;
use std::fs::File;

let points = vec![
    point!(x: -75.343, y: 39.984),
    point!(x: -75.534, y: 39.123),
];

let fc = feature_collection(points.iter().map(|p| p.into()).collect();

// 保存为GeoJSON文件
let file = File::create("points.geojson").unwrap();
serde_json::to_writer_pretty(file, &fc).unwrap();

高级用法

1. 自定义坐标参考系统(CRS)

use turf::projection::web_mercator::web_mercator;

let point = point!(x: -75.343, y: 39.984);
let projected = web_mercator(&point);

2. 空间索引

use turf::kdbush::KDBush;

let points = vec![
    point!(x: -75.343, y: 39.984),
    point!(x: -75.534, y: 39.123),
    // 更多点...
];

let index = KDBush::new(points.iter().map(|p| (p.x(), p.y())).collect());
let neighbors = index.within_radius(-75.4, 39.9, 10.0);

3. 地理空间分析

use turf::convex::convex_hull;
use turf::dissolve::dissolve;

// 计算凸包
let hull = convex_hull(&feature_collection);

// 合并重叠的多边形
let dissolved = dissolve(&feature_collection);

性能提示

1. 对于大量数据，考虑使用空间索引(KDBush)
2. 批量处理数据而不是单个操作
3. 使用&Geometry引用而不是克隆几何对象

下面是一个完整的Turf库使用示例：

use turf::{
    geometry::{Geometry, Point, LineString, Polygon},
    helpers::point,
    distance::distance,
    buffer::buffer,
    boolean_contains::boolean_contains,
    boolean_within::boolean_within,
    bbox::bbox,
    center::center,
    projection::web_mercator::web_mercator,
    kdbush::KDBush,
    convex::convex_hull,
    dissolve::dissolve
};
use std::fs::File;

fn main() {
    // 1. 创建几何对象
    let point1 = point!(x: -75.343, y: 39.984);
    let point2 = point!(x: -75.534, y: 39.123);
    
    let line = LineString::new(vec![point1.clone(), point2.clone()]);
    
    let polygon = Polygon::new(vec![
        vec![
            point!(x: -75.5, y: 40.0),
            point!(x: -75.5, y: 39.0),
            point!(x: -75.0, y: 39.0),
            point!(x: -75.0, y: 40.0),
            point!(x: -75.5, y: 40.0),
        ]
    ]);

    // 2. 计算距离
    let dist = distance(&point1, &point2);
    println!("两点距离: {}公里", dist);

    // 3. 创建缓冲区
    let buffered = buffer(&point1, 5.0, Some("kilometers"));
    println!("创建了半径为5公里的缓冲区");

    // 4. 空间关系判断
    let is_contained = boolean_contains(&polygon, &point1);
    let is_within = boolean_within(&point1, &polygon);
    println!("点是否在多边形内: {}, 点是否在多边形中: {}", is_contained, is_within);

    // 5. 几何操作
    let bounds = bbox(&polygon);
    println!("多边形边界框: {:?}", bounds);
    
    let centroid = center(&polygon);
    println!("多边形中心点: {:?}", centroid);

    // 6. 坐标转换
    let projected = web_mercator(&point1);
    println!("投影后的坐标: {:?}", projected);

    // 7. 空间索引
    let points = vec![point1.clone(), point2.clone()];
    let index = KDBush::new(points.iter().map(|p| (p.x(), p.y())).collect());
    let neighbors = index.within_radius(point1.x(), point1.y(), 100.0);
    println!("附近点数量: {}", neighbors.len());

    // 8. 地理空间分析
    let hull = convex_hull(&points);
    println!("凸包几何体: {:?}", hull);

    // 9. 保存为GeoJSON
    let fc = feature_collection(points.iter().map(|p| p.into()).collect());
    let file = File::create("output.geojson").unwrap();
    serde_json::to_writer_pretty(file, &fc).unwrap();
    println!("GeoJSON文件已保存");
}

Turf库为Rust开发者提供了强大的地理空间计算能力，适用于GIS应用、地图服务、位置分析等多种场景。