README.md

Useful links

• https://github.com/caseypt/node-pollster
• https://github.com/jgoodall/us-maps

index.js

'use strict'
var topojson = require('topojson');
var fs = require('fs');
var path = require('path');
var pollster = require('pollster');

var topojsonFilename = path.join(__dirname, 'us_states.topojson');
var outputFile = path.join(__dirname, 'us_states-enriched-2016-president.topojson');


function loadPollData () {
    return new Promise((resolve, reject) => {
        pollster.charts({topic: '2016-president'}, data => {
            var dataMap = {};
            data.forEach(object => {
                // console.log(object);
                dataMap[object.state] = {};
                object.estimates.forEach(estimate => {
                    dataMap[object.state][estimate.choice] = estimate.value;
                });
            });
            console.log(dataMap);
            resolve(dataMap);
        });
    });
}

function loadTopojsonFile (topojsonFilename) {
    return new Promise((resolve, reject) => {
        fs.readFile(topojsonFilename, 'utf8', function (err, data) {
            if (err) {
                return reject(err);
            }
            try {
                var norge = JSON.parse(data);
            } catch (error) {
                return reject(error);
            }
            resolve(norge);
        });
    });
}

function enrichTopojson(dataSets) {
    return new Promise((resolve, reject) => {
        var electionData = dataSets[0];
        var topojsonData = dataSets[1];
        console.log(topojsonData);
        var states = topojson.feature(topojsonData, topojsonData.objects.state);
        // console.log(states);

        states.features.forEach((stateObject, i) => {
            var state = stateObject.properties.STUSPS10;
            console.log(JSON.stringify(stateObject));
            // console.log(JSON.stringify(state));
            // Remove unwanted chars.
            if (typeof electionData[state] === 'object') {
                stateObject.properties.clinton = electionData[state].Clinton;
                stateObject.properties.trump = electionData[state].Trump;
                // Format the maps
                var fillColor = '#c0c0c0';
                if (stateObject.properties.clinton > stateObject.properties.trump) {
                    fillColor = '#0000ff';
                } else if (stateObject.properties.trump > 0) {
                    fillColor = '#ff0000';
                }
                stateObject.properties.fill = fillColor;
                stateObject.properties.stroke = '#000000';
                var diff = Math.abs(stateObject.properties.clinton - stateObject.properties.trump) / 40;
                stateObject.properties['fill-opacity'] = diff;
                // console.log(municipality, 'opacity:', stateObject.properties['fill-opacity']);
                stateObject.properties['stroke-opacity'] = .2;
                stateObject.properties['stroke-width'] = 1;
            } else {
                console.log('NOT FOUND!', state);
            }

        });
        resolve(topojsonData);
    });
}

//  { id: 624,
    // title: '2016 General Election: Trump vs. Clinton',
    // slug: '2016-general-election-trump-vs-clinton',
    // topic: '2016-president',
    // state: 'US',
    // short_title: '2016 President: Trump vs. Clinton',
    // election_date: '2016-11-08',
    // poll_count: 352,
    // last_updated: '2016-10-28T07:01:21.000Z',
    // url: 'http://elections.huffingtonpost.com/pollster/2016-general-election-trump-vs-clinton',
    // estimates: [ [Object], [Object], [Object] ] }

// [ { choice: 'Trump',
  //   value: '54.7',
  //   lead_confidence: 100,
  //   first_name: 'Donald',
  //   last_name: 'Trump',
  //   party: 'Rep',
  //   incumbent: false },
  // { choice: 'Clinton',
  //   value: '30.9',
  //   lead_confidence: 0,
  //   first_name: 'Hillary',
  //   last_name: 'Clinton',
  //   party: 'Dem',
  //   incumbent: false },
  // { choice: 'Other',
  //   value: '8.9',
  //   lead_confidence: null,
  //   first_name: '',
  //   last_name: 'Other',
  //   party: null,
  //   incumbent: false } ]




function writeTopojson(topojsonData, topojsonFilename) {
    return new Promise((resolve, reject) => {
        var wstream = fs.createWriteStream(topojsonFilename);
        wstream.write(JSON.stringify(topojsonData));
        wstream.end();
        resolve('File saved as: ' + topojsonFilename);
    });
}

function calcOpacity (value) {
    if (value > 1) {
        value = 0;
    }
    value = 1 - value;
    if (value > .9) {
        value = .9;
    }
    return value;
}

Promise.all([loadPollData(), loadTopojsonFile(topojsonFilename)])
    .then(enrichTopojson)
    .then(topojsonData => {
        return writeTopojson(topojsonData, outputFile);
    })
    .then(console.log)
    .catch(console.error);

us_states-enriched-2016-president.topojson