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#!/usr/bin/env node
/**
* Report features which overlap
*/
const fs = require('fs')
const { Readable, Transform, pipeline } = require('stream')
const ndjson = require('ndjson')
const argv = require('yargs/yargs')(process.argv.slice(2))
.argv
if (argv._.length < 2) {
console.error("Usage: ./reportOverlap.js input.geojson output.geojson")
process.exit(1)
}
const inputFile = argv._[0]
const outputFile = argv._[1]
if (!fs.existsSync(inputFile)) {
console.error(`${inputFile} not found`)
process.exit(1)
}
let sourceCount = 0
const features = {}
/**
* Index features by geometry. Used as a first pass, so a second pass can easily compare
* features with the same geometry.
*/
const index = new Transform({
readableObjectMode: true,
writableObjectMode: true,
transform(feature, encoding, callback) {
sourceCount++
if (!argv.quiet) {
if (process.stdout.isTTY && sourceCount % 10000 === 0) {
process.stdout.write(` ${sourceCount.toLocaleString()}\r`)
}
}
const geometryKey = feature.geometry.coordinates.join(',')
if (!(geometryKey in features)) {
features[geometryKey] = []
}
features[geometryKey].push(feature)
callback()
}
})
let totalFeaturesWhichOverlap = 0
let countGroupsOfOverlaps = 0
/**
* Report features with the same geometry.
*/
let featureIndex = 0
const reportOverlap = new Transform({
readableObjectMode: true,
writableObjectMode: true,
transform(key, encoding, callback) {
featureIndex++
if (!argv.quiet) {
if (process.stdout.isTTY && featureIndex % 10000 === 0) {
process.stdout.write(` ${featureIndex.toLocaleString()} / ${sourceCount.toLocaleString()} (${Math.round(featureIndex / sourceCount * 100)}%)\r`)
}
}
const sharedGeometry = features[key]
if (sharedGeometry.length === 1) {
// only one feature with this geometry
} else {
totalFeaturesWhichOverlap += sharedGeometry.length
countGroupsOfOverlaps++
this.push({
type: 'Feature',
properties: {
count: sharedGeometry.length
},
geometry: sharedGeometry[0].geometry
})
}
callback()
}
})
// first pass to index by geometry
console.log('Pass 1/2: index by geometry')
pipeline(
fs.createReadStream(inputFile),
ndjson.parse(),
index,
err => {
if (err) {
console.log(err)
process.exit(1)
} else {
console.log(` of ${sourceCount.toLocaleString()} features found ${Object.keys(features).length.toLocaleString()} unique geometries`)
// second pass to report overlapping features
console.log('Pass 2/2: report overlapping features')
pipeline(
Readable.from(Object.keys(features)),
reportOverlap,
ndjson.stringify(),
fs.createWriteStream(outputFile),
err => {
if (err) {
console.log(err)
process.exit(1)
} else {
console.log(`Total overlapping features: ${totalFeaturesWhichOverlap}`)
console.log(`Locations with overlapping features: ${countGroupsOfOverlaps}`)
process.exit(0)
}
}
)
}
}
)
|
