exercise

exercise.sc

// Write some code, that will flatten an array of arbitrarily
// nested arrays of integers into a flat array of integers.
// e.g. [[1,2,[3]],4] -> [1,2,3,4].
val a = List(List(1,2,List(3)),4)
val b = List(1,2,List(3))
///////////////////
//implicit class WrapFlatten(val ls: List[Any]) {
def flatten(ls: List[Any]): List[Any] = ls flatMap {
  case i: List[_] => flatten(i)
  case e => List(e)
}
val k = List(1, List(2, 3), List(List(List(List(4)), List(5)), List(6, 7)), 8)
flatten(k)
flatten(a)
//val z = k.flatten
///////////////////

// We have some customer records in a text file
// (customers.json, attached) one customer per line,
// JSON-encoded. We want to invite any customer within 100km
// of our Dublin office (GPS coordinates 53.3381985, -6.2592576)
// to some food and drinks on us.
// Write a program that will read the full list of customers and
// output the names and user ids of matching customers (within 100km),
// sorted by user id (ascending).
// You can use the first formula from this Wikipedia
// article to calculate distance, don’t forget, you’ll need to
// convert degrees to radians. Your program should be fully
// tested too.

/* https://en.wikipedia.org/wiki/Great-circle_distance
* customer names and userId
* */

import org.json4s._
import org.json4s.jackson.JsonMethods._
//import org.json4s.native.JsonMethods._
implicit val formats = DefaultFormats // Brings in default date formats etc.

////////////////////////////
import math._
def haversine(lat1: Double, lon1: Double, lat2: Double, lon2: Double) = {
  val dLat = (lat2 - lat1).toRadians
  val dLon = (lon2 - lon1).toRadians

  val a = pow(sin(dLat / 2), 2) + pow(sin(dLon / 2), 2) * cos(lat1.toRadians) * cos(lat2.toRadians)
  val c = 2 * asin(sqrt(a))
  6371 * c
}
////////////////////////////
case class Customer(latitude: String, user_id: Int, name: String, longitude: String)
val a1 = """{"latitude": "52.986375", "user_id": 12, "name": "Christina McArdle", "longitude": "-6.043701"}"""
val b1 = """{"latitude": "53", "user_id": 13, "name": "Olive Ahearn", "longitude": "-7"}"""

val pa = parse(a1).extract[Customer]
val pb = parse(b1).extract[Customer]
//////////////////////////////////
val intercomLatitude = 53.3381985
val intercomLongitude = -6.2592576
val path = "/home/gustavo/workspace/funprog-assignements/montecarlo/src/main/resources/customers.txt"

val inputLines = io.Source
  .fromFile(path)
  .getLines
  .toList

inputLines.length

val parsed = inputLines
  .map(parse(_).extract[Customer])
  .map(cust => (cust.name, cust.user_id, haversine(cust.latitude.toDouble, cust.longitude.toDouble, intercomLatitude, intercomLongitude)))
  .filter(_._3 <= 100)
  .sortBy(_._2)

parsed.length
parsed.foreach(x => println(s"${x._1} | ${x._2}"))