地域メッシュの GeoJSON 変換

mesh2geojson.js

'use strict';

var fs = require('fs');
var path = require('path');

var _ = require('underscore');
var concat = require('concat-stream');
var csv = require('csv');
var GeoJSON = require('geojson');
var iconv = require('iconv');


var latlng = function (_mesh) {
  var mesh = _mesh.toString();
  var mesh1 = mesh.slice(0, 4);
  var mesh2 = mesh.slice(4, 6);
  var mesh3 = mesh.slice(6, 8);

  var latDeg = parseInt(mesh1.slice(0, 2)) / 1.5;
  var latMin = parseInt(mesh2.slice(0, 1)) * 5;
  var latSec = parseInt(mesh3.slice(0, 1)) * 30;
  var lngDeg = parseInt(mesh1.slice(2, 4)) + 100;
  var lngMin = parseInt(mesh2.slice(1, 2)) * 7.5;
  var lngSec = parseInt(mesh3.slice(1, 2)) * 45;

  var lat = ((latDeg * 3600) + (latMin * 60) + latSec) / 3600;
  var lng = ((lngDeg * 3600) + (lngMin * 60) + lngSec) / 3600;

  return [ lat, lng ];
};

var f = fs.statSync(process.argv[2]).isFile() ? path.resolve(process.argv[2]) : undefined;
var filein = fs.createReadStream(f);
var fileconv = new iconv.Iconv('Shift_JIS', 'UTF-8//TRANSLIT//IGNORE');
var fileout = fs.createWriteStream(f.replace(/\.csv$/, '.json'));

filein
  .pipe(fileconv)
  .pipe(csv.parse())
  .pipe(csv.transform(function (values) {
    return {
      code: parseInt(values[0]),
      name: values[1],
      coords: [ latlng(values[2]) ]
    };
  }))
  .pipe(concat(function (_data) {
    var data = _.reduce(_data, function (memo, item) {
      if (!_.isArray(memo)) return [ item ];
      var last = _.last(memo);
      if (last.code === item.code) {
        last.coords.push(item.coords[0]);
      } else {
        memo.push(item);
      }
      return memo;
    });
    var geoData = GeoJSON.parse(data, { 'MultiPoint': 'coords' });
    fileout.end(JSON.stringify(geoData));
  }));

package.json

{
  "name": "mesh2latlng",
  "author": "Yu I.",
  "license": "UNLICENSE",
  "scripts": {
    "convert": "node ./mesh2geojson.js"
  },
  "dependencies": {
    "concat-stream": "^1.4.8",
    "csv": "^0.4.1",
    "geojson": "^0.2.0",
    "iconv": "^2.1.6",
    "underscore": "^1.8.3"
  }
}