segmentReduce

描述

¥Description

Reduce 2-vertex line segment in any GeoJSON object, similar to Array.reduce() (Multi)Point geometries do not contain segments therefore they are ignored during this operation.

参数

¥Parameters

名称	类型	描述
geojson	FeatureCollection | 特性 | 几何图形	任意 GeoJSON
callback	segmentReduceCallback	a method that takes (previousValue, currentSegment, currentIndex)
initialValue?	Reducer	Value to use as the first argument to the first call of the callback.

返回

¥Returns

Reducer

示例

¥Examples

var polygon = turf.polygon([
  [
    [-50, 5],
    [-40, -10],
    [-50, -10],
    [-40, 5],
    [-50, 5],
  ],
]);

// Iterate over GeoJSON by 2-vertex segments
turf.segmentReduce(
  polygon,
  function (
    previousSegment,
    currentSegment,
    featureIndex,
    multiFeatureIndex,
    geometryIndex,
    segmentIndex,
  ) {
    //= previousSegment
    //= currentSegment
    //= featureIndex
    //= multiFeatureIndex
    //= geometryIndex
    //= segmentIndex
    return currentSegment;
  },
);

// Calculate the total number of segments
var initialValue = 0;
var total = turf.segmentReduce(
  polygon,
  function (previousValue) {
    previousValue++;
    return previousValue;
  },
  initialValue,
);

安装

¥Installation

$ npm install @turf/meta

import { segmentReduce } from "@turf/meta";
const result = segmentReduce(...);

$ npm install @turf/turf

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