bmcminn · March 26, 2019 22:54 · Mar 26, 2019
diff --git a/zip-distance.js b/zip-distance.js
@@ -0,0 +1,127 @@
+
+const ZIPCODES  = require('./zipcodes.js')
+const sqlite    = require('sqlite')
+const Promise   = require('bluebird')
+
+
+// http://www.zipcodeapi.com/API
+
+/**
+ * Calculates distance between two ZIPCODES
+ * @sauce: https://www.movable-type.co.uk/scripts/latlong.html
+ * @param  {object}  zip1       Object containing zip, lat, lng
+ * @param  {object}  zip2       Object containing zip, lat, lng
+ * @param  {integer} PRECISION  Flag to return the result in kilometers or miles
+ * @return {double}             A double representing the distance between the two points
+ */
+function zipDistance(zip1, zip2, PRECISION=3) {
+    const R  = 6371
+    // const R  = 6371e3 // meters
+    // const M  = R / 1.609
+
+    const φ1 = degressToRadians(zip1.lat)
+    const φ2 = degressToRadians(zip2.lat)
+    const Δφ = degressToRadians((zip2.lat-zip1.lat))
+    const Δλ = degressToRadians((zip2.lng-zip1.lng))
+
+    let a = Math.sin(Δφ/2) * Math.sin(Δφ/2) +
+            Math.cos(φ1) * Math.cos(φ2) *
+            Math.sin(Δλ/2) * Math.sin(Δλ/2)
+
+    let c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a))
+
+    return (R * c).toFixed(PRECISION)
+}
+
+
+/**
+ * Calculate the lat and lng ranges for a given "radius"
+ * @param  {[type]} zip1   [description]
+ * @param  {[type]} radius [description]
+ * @return {[type]}        [description]
+ */
+function getZipRadius(zip1, radius) {
+
+    let DIST = 0.01035 * radius
+
+    return {
+        latMin: zip1.lat - DIST,
+        latMax: zip1.lat + DIST,
+        lngMin: zip1.lng - DIST,
+        lngMax: zip1.lng + DIST,
+    }
+}
+
+
+/**
+ * [degressToRadians description]
+ * @param  {[type]} degrees [description]
+ * @return {[type]}         [description]
+ */
+function degressToRadians(degrees) {
+  return degrees * (Math.PI/180)
+}
+
+
+/**
+ * Converts Km to miles
+ * @param  {float}  km      distance in kilometers
+ * @return {double} miles   distance in miles
+ */
+function kmToMiles(km, PRECISION=3) {
+    return (km / 1.609).toFixed(PRECISION)
+}
+
+
+/**
+ * [getZipsInRadius description]
+ * @param  {[type]} zip    [description]
+ * @param  {[type]} zips   [description]
+ * @param  {[type]} radius [description]
+ * @return {[type]}        [description]
+ */
+function getZipsInRadius(zip, zips, radius) {
+
+    const RADIUS = getZipRadius(zip, radius)
+
+    return zips.filter(el => {
+        if (RADIUS.latMin <= el.lat && el.lat <= RADIUS.latMax
+        &&  RADIUS.lngMin <= el.lng && el.lng <= RADIUS.lngMax
+        ) {
+
+            let distance = zipDistance(zip, el)
+
+            if (distance <= radius) {
+                return el
+            }
+        }
+    })
+}
+
+
+
+
+
+// const TARGET = ZIPCODES[0]
+const RADIUS = 100
+
+
+const TARGET = {
+    lat: 30.3,
+    lng: -97.6,
+    zip_code: '???',
+}
+
+
+// let res = getZipsInRadius(TARGET, ZIPCODES, RADIUS)
+
+// res.map(el => {
+//     console.log(`distance from ${TARGET.zip_code} to ${el.zip_code} is`, kmToMiles(zipDistance(TARGET, el)), 'miles')
+// })
+
+
+getZipsInRadius(TARGET, ZIPCODES, RADIUS)
+    .map(el => {
+        console.log(`distance from ${TARGET.zip_code} to ${el.zip_code} is`, kmToMiles(zipDistance(TARGET, el)), 'miles')
+    })
+