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 要素
property	string | number	用于创建聚类的 GeoJSON 属性键/值
callback	clusterReduceCallback	一个接收(previousValue, cluster, clusterValue, currentIndex)
initialValue?	any	用作回调函数首次调用的第一个参数的值。

返回

¥Returns

任意 缩减后的值。

¥any The value that results from the reduction.

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(...);