Datastringer example: Greater London crime stats

listofpolys.json

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"51.486533,-0.238312:51.489376,-0.248684:51.485696,-0.252531:51.47683,-0.258219:51.473819,-0.265078:51.474655,-0.281137:51.484191,-0.304725:51.480678,-0.318776:51.47064,-0.319446:51.465622,-0.308907:51.449395,-0.329148:51.442871,-0.329315:51.436347,-0.320282:51.429656,-0.33149:51.435678,-0.331992:51.439024,-0.331156:51.44354,-0.311416:51.450065,-0.319613:51.462276,-0.334501:51.454581,-0.342029:51.457592,-0.375319:51.459265,-0.385189:51.445715,-0.364947:51.441198,-0.373311:51.435009,-0.391713:51.432834,-0.392214:51.425975,-0.396229:51.421291,-0.393553:51.407742,-0.370468:51.409247,-0.346211:51.400883,-0.332494:51.392518,-0.316267:51.395362,-0.30991:51.405734,-0.313758:51.426812,-0.311918:51.433503,-0.302884:51.433336,-0.299371:51.427481,-0.286992:51.428987,-0.279632:51.423968,-0.251361:51.435845,-0.244502:51.444879,-0.25939:51.458094,-0.254539:51.46512,-0.23781:51.464786,-0.233461:51.473317,-0.229781:51.471812,-0.224595",
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"51.537889,-0.190134:51.532201,-0.198331:51.526681,-0.204354:51.529692,-0.215896:51.529358,-0.203517:51.522833,-0.192811:51.509785,-0.188796:51.509953,-0.185952:51.501755,-0.162867:51.50025,-0.16019:51.490046,-0.153331:51.489544,-0.151659:51.486198,-0.135934:51.4867,-0.129577:51.489376,-0.120042:51.508782,-0.113183:51.512295,-0.114856:51.516979,-0.12389:51.516979,-0.131585:51.512295,-0.135097:51.517648,-0.150655:51.526012,-0.155841:51.535213,-0.172067"
]

london-stringer.js

var sync = require('synchronize');
var utils = require('./utils.js');
var listOfPolys = require('./listofpolys.json');

function stringer(numberOfMonths, threshold, callback) {

  sync.fiber(function() {
    // get last update date, so that we know where to start from.
    var dateJson = sync.await(utils.getTheJSON(
      "http://data.police.uk/api/crime-last-updated", sync.defer()));

    var currentDate = new Date(JSON.parse(dateJson).date);

    var lastUpdateTimeRef = new Date(0);
    try {
      var refJSON = sync.await(utils.readAsset(
        'london-stringer-reference/lastUpdate-' + numberOfMonths + '-' + threshold + '.json',
        sync.defer()));
      lastUpdateTimeRef = new Date(JSON.parse(refJSON));
    } catch (except) {}
    if (currentDate < lastUpdateTimeRef) {
      //return;
      console.log("ERROR");
      console.log("current date:", currentDate);
      console.log("lastUpdateTimeRef:", lastUpdateTimeRef);
    }

    utils.writeAsset(
        'london-stringer-reference/lastUpdate-' + numberOfMonths + '-' + threshold + '.json',
        JSON.stringify(currentDate),
      function(err) {
        console.log(err);
      });

    // query crime stats for each month
    var crimeArray = [];
    while (numberOfMonths) {

      var crime = {};

      // build query for current month
      var currMonth = currentDate.getMonth() + 1; // months start at 0 ¬_¬
      currMonth = currMonth > 9 ? String(currMonth) : '0' + String(currMonth);
      var timeQuery = "&date=" + currentDate.getFullYear() + "-" + currMonth;

      console.log('police-uk: fetching data for ' + timeQuery);

      for (var i = 0; i < listOfPolys.length; i++) {
        var baseQuery =
          "http://data.police.uk/api/crimes-street/all-crime?poly=" +
          listOfPolys[i];
        try {
          var data = sync.await(crimeQuery(baseQuery + timeQuery, sync.defer()));
          mergeCrime(crime, data);
        } catch (e) {
          console.log('somethin bad happened to that poly for that month, skipping.', e);
        }
      }

      crimeArray.push(crime);

      currentDate.setMonth(currentDate.getMonth() - 1);
      numberOfMonths--;

    } //while

    console.log("Crime Array: ", crimeArray);
    // compute average for each category, over the time range
    var categories = Object.keys(crimeArray[0]);
    numberOfMonths = crimeArray.length;
    var categoryAverages = {};
    for (var c = 0; c < categories.length; c++) {
      var cat = categories[c];
      categoryAverages[cat] = 0;

      for (var i = 0; i < crimeArray.length; i++) {
        if (cat in crimeArray[i]) {
          categoryAverages[cat] += crimeArray[i][cat];
        }
      }

      categoryAverages[cat] /= numberOfMonths;
    }

    // for each category, compute the diff btw crime amount for last month and
    // average.
    // callback if > threshold
    for (var c = 0; c < categories.length; c++) {
      var cat = categories[c];
      var categoryDiff = (crimeArray[0][cat] - categoryAverages[cat]) / categoryAverages[cat] * 100;

      console.log("Crime statistics updated for the last time on: " + currentDate);
      console.log("category: " + cat + ",  " + "diff: " + Math.round(
        categoryDiff) + "%");
      /*if (Math.abs(categoryDiff) > Math.abs(threshold)) {
        callback('crime-stringer', cat + ', diff: ' + categoryDiff);
      }*/
    }
  });
} //stringer

function crimeQuery(path_json, callback) {
  utils.getTheJSON(path_json, process);

  function process(err, json) {
    if (err) {
      callback(err);
      return;
    }

    if (!json) {
      callback('No JSON could be fetched for ' + path_json);
      return;
    }

    var data = JSON.parse(json);
    var monthCrimeStat = {};
    for (var i = 0; i < data.length; i++) {
      if (!(data[i].category in monthCrimeStat)) {
        monthCrimeStat[data[i].category] = 0; // 1st crime seen for this category
      }
      monthCrimeStat[data[i].category] += 1;
    }
    callback(undefined, monthCrimeStat);
  }
}

function mergeCrime(receiver, toMerge) {
  var p;
  for (p in toMerge) {
    if (receiver[p]) {
      receiver[p] += toMerge[p];
    }
    else {
      receiver[p] = toMerge[p];
    }
  }
}

module.exports = stringer;

mailer.js

var nm = require("nodemailer");
var utils = require('./utils.js');
var t = nm.createTransport();

function sendAlert(stringerName, alertContent) {
  utils.readAsset('user-email.json', function(err, data) {
    t.sendMail({
      from: "bot@data.string.er",
      to: data,
      subject: "ALERT for " + stringerName,
      text: "This is a Datastringer automatically-generated alert.\n On today's run, " + stringerName + "generated an alert, with the " +
          "following content:\n" + alertContent // TODO pretty print the object
    },
    function(err, info) {
      if(err) {
        console.log(err);
      }
    });
  });

}

module.exports = {
  sendAlert: sendAlert,
};