Cluster Stats

<!--
  示例：分类聚合统计
  核心逻辑：clusterEach 按类别分组，统计数量与均值并写回界面
  依赖：Turf.js 7 · jsDelivr CDN
-->
<!DOCTYPE html>
<html lang="zh-CN">
<head>
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<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>分类聚合统计</title>
<style>
  html,body{height:100%;margin:0}
  body{display:flex;flex-direction:column;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif;color:#16181d;background:#fff}
  .bar{flex:0 0 auto;display:flex;gap:12px;align-items:center;padding:8px 12px;
       background:#f6f7f9;border-bottom:1px solid #e3e6ea;font-size:12px;color:#58606e;flex-wrap:wrap}
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  .bar input[type=range]{width:150px}
  .bar b{color:#1f5fd0;font-weight:600}
  .hint{color:#8a929f}
  svg{flex:1 1 auto;min-height:0;width:100%;display:block;background:#fbfcfd}
  .out{flex:0 0 auto;display:flex;gap:20px;flex-wrap:wrap;padding:8px 12px;
       border-top:1px solid #e3e6ea;
       font-family:ui-monospace,Consolas,monospace;font-size:11.5px;color:#3a4250}
  .out b{font-weight:600;color:#1f5fd0}
</style>
</head>
<body>
<div class="bar"><span>600 个点按类别分组</span><span class="hint">颜色对应三类 · 均值来自 v 字段</span></div>
<svg id="stage" viewBox="0 0 640 320" preserveAspectRatio="xMidYMid meet"></svg>
<div class="out">
  <span>A 组 <b id="ca">—</b></span>
  <span>B 组 <b id="cb">—</b></span>
  <span>C 组 <b id="cc">—</b></span>
  <span>总计 <b id="ct">—</b></span>
</div>
<script src="https://cdn.jsdelivr.net/npm/@turf/turf@7/turf.min.js"></script>
<script>
(function () {
  'use strict';

  if (typeof turf === 'undefined') {
    document.body.innerHTML =
      '<div style="padding:24px;color:#b42318">Turf.js 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    return;
  }

  function makeProjection(BOX, W, H, PAD) {
    var kx = Math.cos(((BOX[1] + BOX[3]) / 2) * Math.PI / 180);
    var x0 = BOX[0] * kx, x1 = BOX[2] * kx;
    var y0 = BOX[1], y1 = BOX[3];
    var s = Math.min((W - PAD * 2) / (x1 - x0), (H - PAD * 2) / (y1 - y0));
    var ox = (W - (x1 - x0) * s) / 2;
    var oy = (H - (y1 - y0) * s) / 2;
    var to = function (c) {
      return [(c[0] * kx - x0) * s + ox, (y1 - c[1]) * s + oy];
    };
    to.inverse = function (px, py) {
      return [((px - ox) / s + x0) / kx, y1 - (py - oy) / s];
    };
    return to;
  }

  function linePath(pr, coords) {
    var d = '';
    for (var i = 0; i < coords.length; i++) {
      var p = pr(coords[i]);
      d += (i ? 'L' : 'M') + p[0].toFixed(1) + ' ' + p[1].toFixed(1);
    }
    return d;
  }

  function ringPath(pr, ring) { return linePath(pr, ring) + 'Z'; }

  function polyPath(pr, rings) {
    var d = '';
    for (var i = 0; i < rings.length; i++) d += ringPath(pr, rings[i]);
    return d;
  }
  var BOX = [116.28, 39.82, 116.52, 39.96];
  var pr = makeProjection(BOX, 640, 320, 22);
  var stage = document.getElementById('stage');

  var COLORS = { A: '#1f5fd0', B: '#0f8a7a', C: '#c2410c' };
  var feats = [];
  var cats = ['A', 'B', 'C'];

  for (var i = 0; i < 600; i++) {
    var cat = cats[i % 3];
    feats.push(turf.point(
      [116.29 + Math.random() * 0.22, 39.83 + Math.random() * 0.12],
      { cat: cat, v: cat === 'A' ? 40 + Math.random() * 20 :
              (cat === 'B' ? 60 + Math.random() * 30 : 25 + Math.random() * 15) }
    ));
  }

  var fc = turf.featureCollection(feats);
  var stats = {};

  turf.clusterEach(fc, 'cat', function (cluster, cat) {
    var sum = 0;
    turf.featureEach(cluster, function (f) {
      sum += f.properties.v;
    });
    stats[cat] = {
      count: cluster.features.length,
      mean: sum / cluster.features.length
    };
  });

  var parts = ['<rect x="0" y="0" width="640" height="320" fill="none" stroke="#e3e6ea"/>'];

  turf.featureEach(fc, function (f) {
    var c = pr(f.geometry.coordinates);
    parts.push('<circle cx="' + c[0].toFixed(1) + '" cy="' + c[1].toFixed(1) +
               '" r="3" fill="' + COLORS[f.properties.cat] + '" fill-opacity="0.72"/>');
  });

  var lx = 24;
  cats.forEach(function (cat) {
    parts.push('<rect x="' + lx + '" y="288" width="12" height="12" fill="' + COLORS[cat] + '"/>');
    parts.push('<text x="' + (lx + 18) + '" y="299" font-size="12" fill="#3a4250">' +
               cat + ' 组</text>');
    lx += 84;
  });

  stage.innerHTML = parts.join('');

  document.getElementById('ca').textContent =
    stats.A.count + ' 个 · 均值 ' + stats.A.mean.toFixed(1);
  document.getElementById('cb').textContent =
    stats.B.count + ' 个 · 均值 ' + stats.B.mean.toFixed(1);
  document.getElementById('cc').textContent =
    stats.C.count + ' 个 · 均值 ' + stats.C.mean.toFixed(1);
  document.getElementById('ct').textContent = feats.length;
})();
</script>
</body>
</html>