Purple AQI Widget

purpleaqijsnell.js

I've moved this to a proper GitHub project.

Check it out at: 

https://github.com/jasonsnell/PurpleAir-AQI-Scriptable-Widget

@yanlesin My javascript knowledge is pretty limited, but there's only a single network request happening here, right? Seems like this should be fine as is?

Thanks Rob @areohbe - you are correct - single request... That is why I deleted comment...

Hey @areohbe @yanlesin looks like the Springboard widget refresher runs pretty sporadically, too, so it doesn't do anything too hard to the server.

👍 Glad you caught my typos!

Ha, not sure I noticed any! But I did change the gradient colors to be closer to the "official" ones and added in the text color so you can have black text for lighter colors and white text for darker colors.

Hi Jason, if you're interested I cleaned up the indenting of the file (mostly tabs -> spaces), and moved the trends and EPA adjustment stuff into functions. I also simplified toLocaleTimeString() to use your current locale settings where appropriate.

It should otherwise be functionally identical, but easier to read 🙂.

// widget code by Jason Snell <jsnell@sixcolors.com>
// based on code by Matt Silverlock
// gradient routine contributed by Rob Silverii
const API_URL = "https://www.purpleair.com/json?show=";

// Find a nearby PurpleAir sensor ID via https://fire.airnow.gov/
// Click a sensor near your location: the ID is the trailing integers
// https://www.purpleair.com/json has all sensors by location & ID.
let SENSOR_ID = args.widgetParameter || "34663";

// Fetch content from PurpleAir
async function getSensorData(url, id) {
  let req = new Request(`${url}${id}`);
  let json = await req.loadJSON();

  return {
    "val": json.results[0].Stats,
    "adj1": json.results[0].pm2_5_cf_1,
    "adj2": json.results[1].pm2_5_cf_1,
    "ts": json.results[0].LastSeen,
    "hum": json.results[0].humidity,
    "loc": json.results[0].Label,
    "lat": json.results[0].Lat,
    "lon": json.results[0].Lon
  };
}

// Widget attributes: AQI level threshold, text label, gradient start and end colors, text color
const levelAttributes = [
  {
    threshold: 300,
    label: "Hazardous",
    startColor: "9e2043",
    endColor: "7e0023",
    textColor: "ffffff",
  },
  {
    threshold: 200,
    label: "Very Unhealthy",
    startColor: "8f3f97",
    endColor: "6f1f77",
    textColor: "ffffff",
  },
  {
    threshold: 150,
    label: "Unhealthy",
    startColor: "FF3D3D",
    endColor: "D60000",
    textColor: "000000",
  },
  {
    threshold: 100,
    label: "Unhealthy (S.G.)",
    startColor: "FFA63D",
    endColor: "D67200",
    textColor: "000000",
  },
  {
    threshold: 50,
    label: "Moderate",
    startColor: "ffff00",
    endColor: "cccc00",
    textColor: "000000",
  },
  {
    threshold: 0,
    label: "Good",
    startColor: "00e400",
    endColor: "00bb00",
    textColor: "000000",
  },
];

// Get level attributes for AQI
function getLevelAttributes(level, attributes) {
  let applicableAttributes = attributes
    .filter((c) => level > c.threshold)
    .sort((a, b) => b.threshold - a.threshold);
  return applicableAttributes[0];
}

// Function to get the EPA adjusted PPM
function computePM(data) {
  let adj1 = parseInt(data.adj1, 10);
  let adj2 = parseInt(data.adj2, 10);
  let hum = parseInt(data.hum, 10);
  let dataAverage = ((adj1 + adj2)/2);

  // Apply EPA draft adjustment for wood smoke and PurpleAir
  // from https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=349513&Lab=CEMM&simplesearch=0&showcriteria=2&sortby=pubDate&timstype=&datebeginpublishedpresented=08/25/2018

  return ((0.524 * dataAverage) - (.0085 * hum) + 5.71);
}

// Function to get AQI number from PPM reading
function aqiFromPM(pm) {
  if (pm > 350.5) {
    return calcAQI(pm, 500.0, 401.0, 500.0, 350.5);
  } else if (pm > 250.5) {
    return calcAQI(pm, 400.0, 301.0, 350.4, 250.5);
  } else if (pm > 150.5) {
    return calcAQI(pm, 300.0, 201.0, 250.4, 150.5);
  } else if (pm > 55.5) {
    return calcAQI(pm, 200.0, 151.0, 150.4, 55.5);
  } else if (pm > 35.5) {
    return calcAQI(pm, 150.0, 101.0, 55.4, 35.5);
  } else if (pm > 12.1) {
    return calcAQI(pm, 100.0, 51.0, 35.4, 12.1);
  } else if (pm >= 0.0) {
    return calcAQI(pm, 50.0, 0.0, 12.0, 0.0);
  } else {
    return "-";
  }
}

// Function that actually calculates the AQI number
function calcAQI(Cp, Ih, Il, BPh, BPl) {
  let a = (Ih - Il);
  let b = (BPh - BPl);
  let c = (Cp - BPl);
  return Math.round((a/b) * c + Il);
}

// Calculates the AQI level based on
// https://cfpub.epa.gov/airnow/index.cfm?action=aqibasics.aqi#unh
function calculateLevel(aqi) {
  let res = {
    level: "OK",
    label: "fine",
    startColor: "white",
    endColor: "white",
  };

  let level = parseInt(aqi, 10) || 0;

  // Set attributes
  res = getLevelAttributes(level, levelAttributes);
  // Set level
  res.level = level;
  return res;
}

// Function to get the AQI trends suffix
function trendsFromStats(stats) {
  let partLive = parseInt(stats.v1, 10);
  let partTime = parseInt(stats.v2, 10);
  let partDelta = partTime - partLive;

  if (partDelta > 5) {
    theTrend = " Improving";
  } else if (partDelta < -5) {
    theTrend = " Worsening";
  } else {
    theTrend = "";
  }
  return theTrend;
}

async function run() {
  let wg = new ListWidget();
  wg.setPadding(20, 15, 10, 10);

  try {
    console.log(`Using sensor ID: ${SENSOR_ID}`);

    let data = await getSensorData(API_URL, SENSOR_ID);
    let stats = JSON.parse(data.val);
    console.log(stats);

    let theTrend = trendsFromStats(stats);
    console.log(theTrend);

    let epaPM = computePM(data);
    console.log(epaPM);

    let aqi = aqiFromPM(epaPM);
    let level = calculateLevel(aqi);
    let aqiText = aqi.toString();
    console.log(aqi);
    console.log(level.level);

    let startColor = new Color(level.startColor);
    let endColor = new Color(level.endColor);
    let textColor = new Color(level.textColor);
    let gradient = new LinearGradient();
    gradient.colors = [startColor, endColor];
    gradient.locations = [0.0, 1];
    console.log(gradient);

    wg.backgroundGradient = gradient;

    let header = wg.addText("AQI" + theTrend);
    header.textColor = textColor;
    header.font = Font.regularSystemFont(15);

    let content = wg.addText(aqiText);
    content.textColor = textColor;
    content.font = Font.semiboldRoundedSystemFont(45);

    let wordLevel = wg.addText(level.label);
    wordLevel.textColor = textColor;
    wordLevel.font = Font.boldSystemFont(15);

    wg.addSpacer(10);

    let location = wg.addText(data.loc);
    location.textColor = textColor;
    location.font = Font.mediumSystemFont(12);

    let updatedAt = new Date(data.ts * 1000)
      .toLocaleTimeString([], { hour: '2-digit', minute: '2-digit'});
    let ts = wg.addText(`Updated ${updatedAt}`);
    ts.textColor = textColor;
    ts.font = Font.lightSystemFont(10);

    wg.addSpacer(10);

    let purpleMap = 'https://www.purpleair.com/map?opt=1/i/mAQI/a10/cC0&select=' + SENSOR_ID + '#14/' + data.lat + '/' + data.lon;
    wg.url = purpleMap;
  } catch (e) {
    console.log(e);

    let err = wg.addText(`${e}`);
    err.textColor = Color.red();
    err.textOpacity = 30;
    err.font = Font.regularSystemFont(10);
  }

  if (config.runsInApp) {
    wg.presentSmall();
  }

  Script.setWidget(wg);
  Script.complete();
}

await run();

Go to the PurpleAir map and find a location near you, click on that station, and in the URL you'll find a four or five digit number that is the station ID.

…

On Sun, Sep 20, 2020 at 10:07 AM maungtt ***@***.***> wrote: ***@***.**** commented on this gist. ------------------------------ How do i know my nearest location sensor ID? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <https://gist.github.com/4b458e2775e11ff7dd8b21dd26aa504e#gistcomment-3460819>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AA4G3ASXRMVKKNRIBGGK5PDSGYZELANCNFSM4RNV3ACQ> .

geez, should I just make this a GitHub project now? Thanks Adam!

Moved to: https://github.com/jasonsnell/PurpleAir-AQI-Scriptable-Widget