clusterReduce

描述

🌐 Description

减少 GeoJSON 要素中的聚类，类似于 Array.reduce()

🌐 Reduce clusters in GeoJSON Features, similar to Array.reduce()

参数

🌐 Parameters

名称	类型	描述
geojson	FeatureCollection	GeoJSON 特性
property	string | number	用于创建聚类的 GeoJSON 属性键/值
callback	clusterReduceCallback	一个方法，它接收（previousValue，cluster，clusterValue，currentIndex）
initialValue?	any	作为回调的第一次调用的第一个参数使用的值。

返回

🌐 Returns

任意 由归约得到的值。

示例

🌐 Examples

var geojson = turf.featureCollection([
  turf.point([0, 0]),
  turf.point([2, 4]),
  turf.point([3, 6]),
  turf.point([5, 1]),
  turf.point([4, 2]),
]);

// Create a cluster using K-Means (adds `cluster` to GeoJSON properties)
var clustered = turf.clustersKmeans(geojson);

// Iterate over each cluster and perform a calculation
var initialValue = 0;
turf.clusterReduce(
  clustered,
  "cluster",
  function (previousValue, cluster, clusterValue, currentIndex) {
    //=previousValue
    //=cluster
    //=clusterValue
    //=currentIndex
    return previousValue++;
  },
  initialValue,
);

// Calculate the total number of clusters
var total = turf.clusterReduce(
  clustered,
  "cluster",
  function (previousValue) {
    return previousValue++;
  },
  0,
);

// Create an Array of all the values retrieved from the 'cluster' property
var values = turf.clusterReduce(
  clustered,
  "cluster",
  function (previousValue, cluster, clusterValue) {
    return previousValue.concat(clusterValue);
  },
  [],
);

安装

🌐 Installation

$ npm install @turf/clusters

import { clusterReduce } from "@turf/clusters";
const result = clusterReduce(...);

$ npm install @turf/turf

import * as turf from "@turf/turf";
const result = turf.clusterReduce(...);