Turf.js正确使用超详细案例

// 创建围绕 TCU 大学的 2 英里缓冲区
const tcu = turf.point([-97.364, 32.708]);
const buffered = turf.buffer(tcu, 2, {units: 'miles'});

// 可视化：紫色半透明缓冲区
// 用途：学校服务范围、噪音影响区域、配送范围

// 计算纽约和伦敦之间的距离
const from = turf.point([-74.0060, 40.7128]); // 纽约
const to = turf.point([-0.1278, 51.5074]);   // 伦敦

const distance = turf.distance(from, to, {units: 'kilometers'});
console.log(distance); // 约 5570 公里

// 支持单位：degrees, radians, miles, kilometers

// 查找与缓冲区相交的所有人口普查区
const filtered = turf.filter(tracts, bufferZone, {
  predicate: 'intersects' // 或 'within', 'contains', 'crosses', 'disjoint'
});

// 几何中心（几何中心点）
const centroid = turf.centroid(polygon);

// 质心（面积加权中心，适用于不规则形状）
const centerOfMass = turf.centerOfMass(polygon);

// 两者可能不同：对于不规则多边形，质心更准确

// 为一系列点创建凸包
const points = turf.featureCollection([
  turf.point([-76, 39]),
  turf.point([-76, 41]),
  turf.point([-78, 40]),
  turf.point([-77, 38])
]);

const hull = turf.convexHull(points);
// 结果：包围所有点的最小凸多边形

// 为一系列点生成 Voronoi 图
const points = turf.featureCollection([...]); // 多个点
const voronoi = turf.voronoi(points, {
  bbox: [-77, 38, -76, 40] // 边界框
});

// 每个多边形代表该点的"影响区域"

// 创建两个重叠的缓冲区
const buffer1 = turf.buffer(point1, 1, {units: 'miles'});
const buffer2 = turf.buffer(point2, 1, {units: 'miles'});

// 计算重叠区域
const intersection = turf.intersect(buffer1, buffer2);

// 如果无重叠，返回 null

const union = turf.union(polygon1, polygon2, polygon3);
// 结果：所有多边形合并后的单一多边形

const difference = turf.difference(protectedArea, developmentZone);
// 结果：保护区内未开发的区域

// 创建点
const point = turf.point([-76.5, 39.5]);

// 创建线
const line = turf.lineString([
  [-76.5, 39.5],
  [-76.4, 39.6],
  [-76.3, 39.7]
]);

// 创建多边形
const polygon = turf.polygon([[
  [-76.5, 39.5],
  [-76.4, 39.5],
  [-76.4, 39.6],
  [-76.5, 39.6],
  [-76.5, 39.5] // 闭合
]]);

// 创建矩形
const bbox = [-76.5, 39.5, -76.3, 39.7]; // [minX, minY, maxX, maxY]
const rectangle = turf.bboxPolygon(bbox);

// 旋转多边形
const rotated = turf.rotate(polygon, 45, {pivot: 'center'});

// 缩放
const scaled = turf.transformScale(polygon, 2); // 放大 2 倍

// 平移
const translated = turf.translate(polygon, [1, 1]); // 向东北移动

// 计算点的密度
const density = turf.nearestPointDensity(points, {
  radius: 100,
  units: 'kilometers'
});

// 查找最近点
const nearest = turf.nearestPoint(targetPoint, pointCollection);

// 创建网格
const grid = turf.rectangleGrid(bbox, 1, 1, {units: 'kilometers'});

// 六边形网格（更适合空间分析）
const hexGrid = turf.hexGrid(bbox, 1, {units: 'kilometers'});

// 计算两点间的测地线（最短路径）
const greatCircle = turf.greatCircle(start, end);

// 沿线创建点
const along = turf.along(lineString, 5, {units: 'kilometers'});
// 返回从起点开始 5 公里处的点

// 线的长度
const length = turf.length(lineString, {units: 'kilometers'});

npm install @turf/turf

// 导入整个库
const turf = require('@turf/turf');

// 或按需导入（推荐，减小打包体积）
const buffer = require('@turf/buffer');
const distance = require('@turf/distance');
const intersect = require('@turf/intersect');

<!-- CDN 方式 -->
<script src="https://unpkg.com/@turf/turf@7/turf.min.js"></script>
<script>
  const point = turf.point([-76.5, 39.5]);
  const buffered = turf.buffer(point, 1, {units: 'miles'});
</script>

import { buffer, distance, intersect } from '@turf/turf';

const point = turf.point([-76.5, 39.5]);

// 分析现有站点的覆盖范围
const stations = [...]; // 站点位置
const coverage = stations.map(station => 
  turf.buffer(station, 0.5, {units: 'kilometers'}) // 500 米覆盖
);

// 找出未覆盖的区域
const cityBounds = turf.polygon([...]);
const unionCoverage = turf.union(...coverage);
const gaps = turf.difference(cityBounds, unionCoverage);

// 在缺口处建议新站点
const suggestedLocations = turf.centroid(gaps);

// 计算每个医院的服务范围（15 分钟车程 ≈ 10 公里）
const hospitals = [...];
const serviceAreas = hospitals.map(h => 
  turf.buffer(h, 10, {units: 'kilometers'})
);

// 查找未被覆盖的居民区
const residentialAreas = [...];
const uncovered = residentialAreas.filter(area => 
  !serviceAreas.some(service => turf.booleanIntersects(area, service))
);

// 建议新医院位置
const optimalLocation = turf.centerOfMass(turf.union(...uncovered));

// 计算每个社区的绿地可达性
const parks = [...];
const communities = [...];

communities.forEach(community => {
  const nearbyParks = parks.filter(park => {
    const dist = turf.distance(community, park, {units: 'kilometers'});
    return dist < 0.5; // 500 米内有公园
  });
  
  community.properties.greenSpaceAccess = nearbyParks.length > 0;
});

// Shiny/R 或 React 应用中的实时空间过滤
map.on('draw:created', (e) => {
  const drawnPolygon = e.layer;
  
  // 立即过滤显示结果
  const filtered = turf.filter(allFeatures, drawnPolygon, {
    predicate: 'intersects'
  });
  
  // 即时更新地图显示
  updateMapLayer(filtered);
});