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jooyunghan/ListExercises.scala

Created February 10, 2015 00:39
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ListExercises.scala
import scala.collection.mutable.ListBuffer
object ListExercises {
object SetA {
// Exercise 1. print all names in list
def printAllNames = {
val names = IndexedSeq("Ben", "Jafar", "Matt", "Priya", "Brian")
for (i <- 0 until names.length) {
println(names(i))
}
}
//printAllNames
// Exercise 2. use foreach to print all the names in ... whatever
def useForEach = {
val names = Seq("Ben", "Jafar", "Matt", "Priya", "Brian")
names.foreach(name => println(name))
}
//useForEach
case class Bookmark(id: Long, time: Long)
case class Video(id: Long, title: String, boxart: String, url: String, rating: Double, bookmark: Seq[Bookmark])
val newReleases = Seq(
Video(70111470L,
"Die Hard",
"http://cdn-0.nflximg.com/images/2891/DieHard.jpg",
"http://api.netflix.com/catalog/titles/movies/70111470",
4.0,
Seq()),
Video(654356453L,
"Bad Boys",
"http://cdn-0.nflximg.com/images/2891/BadBoys.jpg",
"http://api.netflix.com/catalog/titles/movies/70111470",
5.0,
Seq(Bookmark(432534, 65876586L))),
Video(65432445L,
"The Chamber",
"http://cdn-0.nflximg.com/images/2891/TheChamber.jpg",
"http://api.netflix.com/catalog/titles/movies/70111470",
4.0,
Seq()),
Video(675465L,
"Fracture",
"http://cdn-0.nflximg.com/images/2891/Fracture.jpg",
"http://api.netflix.com/catalog/titles/movies/70111470",
5.0,
Seq(Bookmark(432534, 65876586L))))
// Exercise 3. Project an array of videos into an array of (id,title) using foreach
def projectingSeq = {
val idTitlePairs = new ListBuffer[(Long, String)]
// --- INSERT CODE HERE ---
// user foreach to accumulate (id, title) pairs from each video.
// put the results into idTitlePairs using append() method.
// example: idTitlePairs.append(newItem)
???
// --- INSERT CODE HERE ---
idTitlePairs.toSeq
}
//println(projectingSeq)
// Exercise 4. Use map to project a sequence of videos into a sequence of (id, title) pairs
def useMap = {
// --- INSERT CODE HERE ---
newReleases.map(???) // complete this expression
// --- INSERT CODE HERE ---
}
//println(useMap)
// Exercise 5. Use foreach() to collect only those videos with a rating of 5.0
def filteringSeq = {
val videos = new ListBuffer[Video]
// --- INSERT CODE HERE ---
// user foreach to accumulate video with a rating of 5.0
???
// --- INSERT CODE HERE ---
videos.toSeq
}
//println(filteringSeq)
// Exercise 6. Chain filter and map to collect the ids of videos that have a rating of 5.0
def useFilterAndMap = {
// --- INSERT CODE HERE ---
newReleases // complete this expression
// --- INSERT CODE HERE ---
}
//println(useFilterAndMap)
case class Category(name: String, videos: Seq[Video])
val movieLists = Seq(
Category(name = "New Releases",
videos = Seq(
Video(70111470L,
"Die Hard",
"http://cdn-0.nflximg.com/images/2891/DieHard.jpg",
"http://api.netflix.com/catalog/titles/movies/70111470",
4.0,
Seq()),
Video(654356453L,
"Bad Boys",
"http://cdn-0.nflximg.com/images/2891/BadBoys.jpg",
"http://api.netflix.com/catalog/titles/movies/70111470",
5.0,
Seq(Bookmark(432534, 65876586L))))),
Category(name = "Drama",
videos = Seq(
Video(65432445L,
"The Chamber",
"http://cdn-0.nflximg.com/images/2891/TheChamber.jpg",
"http://api.netflix.com/catalog/titles/movies/70111470",
4.0,
Seq()),
Video(675465L,
"Fracture",
"http://cdn-0.nflximg.com/images/2891/Fracture.jpg",
"http://api.netflix.com/catalog/titles/movies/70111470",
5.0,
Seq(Bookmark(432534, 65876586L)))))
)
// Exercise 7. Flatten the movieLists sequence into a sequence of ids
def flattenMovieLists = {
val allVideoIdsinMovieLists = new ListBuffer[Long]
// --- INSERT CODE HERE ---
// use two nested foreach loops to flatten the movieLists into a sequence of video ids
???
// --- INSERT CODE HERE ---
allVideoIdsinMovieLists.toSeq
}
//println(flattenMovieLists)
// Exercise 8. Use map and flatten to project and flatten the movieLists into a sequence of video ids
def useMapAndFlatten = {
// --- INSERT CODE HERE ---
// use map and flatten the movieLists into a sequence of video ids.
movieLists // complete this expression
// --- INSERT CODE HERE ---
}
//println(useMapAndFlatten)
}
object SetB {
import SetA.Bookmark
case class BoxArt(width: Int, height: Int, url: String)
case class Video(id: Long, title: String, boxarts: Seq[BoxArt], url: String, rating: Double, bookmark: Seq[Bookmark])
case class Category(name: String, videos: Seq[Video])
val movieLists = Seq(
Category(name = "New Releases",
videos = Seq(
Video(70111470L,
"Die Hard",
Seq(BoxArt(150, 200, "http://cdn-0.nflximg.com/images/2891/DieHard150.jpg"),
BoxArt(200, 200, "http://cdn-0.nflximg.com/images/2891/DieHard200.jpg")),
"http://api.netflix.com/catalog/titles/movies/70111470",
4.0,
Seq()),
Video(654356453L,
"Bad Boys",
Seq(BoxArt(200, 200, "http://cdn-0.nflximg.com/images/2891/BadBoys200.jpg"),
BoxArt(150, 200, "http://cdn-0.nflximg.com/images/2891/BadBoys150.jpg")),
"http://api.netflix.com/catalog/titles/movies/70111470",
5.0,
Seq(Bookmark(432534, 65876586L))))),
Category(name = "Drama",
videos = Seq(
Video(65432445L,
"The Chamber",
Seq(BoxArt(150, 200, "http://cdn-0.nflximg.com/images/2891/TheChamber150.jpg"),
BoxArt(200, 200, "http://cdn-0.nflximg.com/images/2891/TheChamber200.jpg")),
"http://api.netflix.com/catalog/titles/movies/70111470",
4.0,
Seq()),
Video(675465L,
"Fracture",
Seq(BoxArt(200, 200, "http://cdn-0.nflximg.com/images/2891/Fracture200.jpg"),
BoxArt(150, 200, "http://cdn-0.nflximg.com/images/2891/Fracture150.jpg"),
BoxArt(300, 200, "http://cdn-0.nflximg.com/images/2891/Fracture300.jpg")),
"http://api.netflix.com/catalog/titles/movies/70111470",
5.0,
Seq(Bookmark(432534, 65876586L)))))
)
// Exercise 9. Retrieve id, title, and a 150x200 box art url for every video
def retrieveIdTitleAndBoxArt = {
// --- INSERT CODE HERE ---
// use one or more map, filter, flatten calls to create a sequence with following items
// List(
// (70111470,Die Hard,http://cdn-0.nflximg.com/images/2891/DieHard150.jpg),
// (654356453,Bad Boys,http://cdn-0.nflximg.com/images/2891/BadBoys150.jpg),
// (65432445,The Chamber,http://cdn-0.nflximg.com/images/2891/TheChamber150.jpg),
// (675465,Fracture,http://cdn-0.nflximg.com/images/2891/Fracture150.jpg))
movieLists // complete this expression
// --- INSERT CODE HERE ---
}
//println(retrieveIdTitleAndBoxArt)
// Exercise 10. Use flatMap to retrieve id, title, and 150x200 box art url for every video
def useFlatMap = {
// --- INSERT CODE HERE ---
// use one or more flatMap, map, filter calls to create a sequence with the following items
// List(
// (70111470,Die Hard,http://cdn-0.nflximg.com/images/2891/DieHard150.jpg),
// (654356453,Bad Boys,http://cdn-0.nflximg.com/images/2891/BadBoys150.jpg),
// (65432445,The Chamber,http://cdn-0.nflximg.com/images/2891/TheChamber150.jpg),
// (675465,Fracture,http://cdn-0.nflximg.com/images/2891/Fracture150.jpg))
movieLists // complete this expression
// --- INSERT CODE HERE ---
}
//println(useFlatMap)
}
object SetC {
import SetA.Bookmark
import SetB._
val boxArts = Seq(
BoxArt(200, 200, "http://cdn-0.nflximg.com/images/2891/Fracture200.jpg"),
BoxArt(150, 200, "http://cdn-0.nflximg.com/images/2891/Fracture150.jpg"),
BoxArt(300, 200, "http://cdn-0.nflximg.com/images/2891/Fracture300.jpg"),
BoxArt(425, 150, "http://cdn-0.nflximg.com/images/2891/Fracture425.jpg"))
// Exercise 11. Use foreach to find the largest box art
def findLargestArt = {
var maxSize = -1
var largest: BoxArt = null
boxArts foreach { art =>
val currentSize = art.width * art.height
if (currentSize > maxSize) {
largest = art
maxSize = currentSize
}
}
largest
}
//println(findLargestArt)
// Exercise 12. Retrieve the largest rating
def findLargestRating = {
val ratings = Seq(2, 3, 1, 4, 5)
// --- INSERT CODE HERE ---
ratings.reduce(???) // complete this expression
// --- INSERT CODE HERE ---
}
//println(findLargestRating)
// Exercise 13. Retrieve url of the largest boxart
def retrieveUrlOfLargest = {
// --- INSERT CODE HERE ---
boxArts // complete this expression
// --- INSERT CODE HERE ---
}
//println(retrieveUrlOfLargest)
// Exercise 14. Reducing with an initial value
def idTitleMap = {
case class Video(id: Long, title: String)
val videos = Seq(
Video(65432445L, "The Chamber"),
Video(675465L, "Fracture"),
Video(70111470L, "Die Hard"),
Video(654356453L, "Bad Boys"))
// expecting the following
// Map(65432445 -> The Chamber, 675465 -> Fracture, 70111470 -> Die Hard, 654356453 -> Bad Boys)
// --- INSERT CODE HERE ---
// Map is immutable and update(k,v) method creates new map
videos.foldLeft(Map.empty[Long, String])((map, video) => ???)
// --- INSERT CODE HERE ---
}
// println(idTitleMap)
// Exercise 15. Retrieve the id, title, and smallest box art url for every video
def retrieveIdTitleSmallestBoxUrl = {
val movieLists = Seq(
Category(name = "New Releases",
videos = Seq(
Video(70111470L,
"Die Hard",
Seq(BoxArt(150, 200, "http://cdn-0.nflximg.com/images/2891/DieHard150.jpg"),
BoxArt(200, 200, "http://cdn-0.nflximg.com/images/2891/DieHard200.jpg")),
"http://api.netflix.com/catalog/titles/movies/70111470",
4.0,
Seq()),
Video(654356453L,
"Bad Boys",
Seq(BoxArt(200, 200, "http://cdn-0.nflximg.com/images/2891/BadBoys200.jpg"),
BoxArt(140, 200, "http://cdn-0.nflximg.com/images/2891/BadBoys140.jpg")),
"http://api.netflix.com/catalog/titles/movies/70111470",
5.0,
Seq(Bookmark(432534, 65876586L))))),
Category(name = "Drama",
videos = Seq(
Video(65432445L,
"The Chamber",
Seq(BoxArt(130, 200, "http://cdn-0.nflximg.com/images/2891/TheChamber130.jpg"),
BoxArt(200, 200, "http://cdn-0.nflximg.com/images/2891/TheChamber200.jpg")),
"http://api.netflix.com/catalog/titles/movies/70111470",
4.0,
Seq()),
Video(675465L,
"Fracture",
Seq(BoxArt(200, 200, "http://cdn-0.nflximg.com/images/2891/Fracture200.jpg"),
BoxArt(120, 200, "http://cdn-0.nflximg.com/images/2891/Fracture120.jpg"),
BoxArt(300, 200, "http://cdn-0.nflximg.com/images/2891/Fracture300.jpg")),
"http://api.netflix.com/catalog/titles/movies/70111470",
5.0,
Seq(Bookmark(432534, 65876586L)))))
)
// --- INSERT CODE HERE ---
// use one or more flatMap, map, reduce
movieLists // complete this expression
// --- INSERT CODE HERE ---
}
//println(retrieveIdTitleSmallestBoxUrl)
}
def main(args: Array[String]): Unit = {
SetA
SetB
SetC
}
}
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