geobuf-to-grid/src/grid-summary.js

Convert a GeoBuf to a regular grid.

#!/usr/bin/env node

/** Print summary statistics on a grid */

import fs from 'fs'

let nodeBuf = fs.readFileSync(process.argv[2])

let off = 0

let zoom = nodeBuf.readInt32LE((off++) * 4)
let west = nodeBuf.readInt32LE((off++) * 4)
let north = nodeBuf.readInt32LE((off++) * 4)
let width = nodeBuf.readInt32LE((off++) * 4)
let height = nodeBuf.readInt32LE((off++) * 4)

console.log(`${width} x ${height} grid at zoom ${zoom}, upper-left ${west}, ${north}`)

let sum = 0
let current = 0

let min = Infinity
let max = -Infinity

while (off < nodeBuf.length / 4) {
  current += nodeBuf.readInt32LE((off++) * 4)

  sum += current
  min = Math.min(min, current)
  max = Math.max(max, current)
}

console.log(`Total ${sum}, average ${sum / (width * height)}, min ${min}, max ${max}`)