Scala Crash Course
scala> val myIntArray:Array[Int] = new Array(3)
myIntArray: Array[Int] = Array(0, 0, 0)
scala> myIntArray
res0: Array[Int] = Array(0, 0, 0)
scala> myIntArray.foreach(println)
0
0
0
scala> myIntArray(0)=10
scala> myIntArray(1)=20
scala> myIntArray(2)=30
scala> myIntArray.foreach(println)
10
20
30
scala> def addOne(x:Int): Int = {
| x+1
| }
addOne: (x: Int)Int
scala> addOne(5)
res6: Int = 6
scala> addOne(50)
res7: Int = 51
scala> def addTwo(x:Int):Int = {
| return x + 2;
| }
addTwo: (x: Int)Int
scala> addTwo(5);
res8: Int = 7
scala> (1 to 10).foreach(x => println(addTwo(x)))
3
4
5
6
7
8
9
10
11
12
scala> def max(x:Int, y:Int): Int = {
| if (x > y) x else y
| }
max: (x: Int, y: Int)Int
scala> max(5,6)
res22: Int = 6
scala> val myArray = Array("Zara","Lara","Sara")
myArray: Array[String] = Array(Zara, Lara, Sara)
scala> var i = 0
i: Int = 0
scala> while (i < myArray.length) {
| println(myArray(i))
| i += 1
| }
Zara
Lara
Sara
scala> myArray.foreach(arg => println(arg))
Zara
Lara
Sara
scala> myArray.foreach(println(_))
Zara
Lara
Sara
scala> myArray.foreach(println)
Zara
Lara
Sara
scala> for(arg <- br="" myarray=""> | println(arg)
Zara
Lara
Sara
$ cat hello.sc
object hello{
def main(args:Array[String]):Unit = {
println("Hello : " + args(0) + " !")
}
}
scala> :load /home/hadoop/Desktop/ScalaTraining/hello.sc
Loading /home/hadoop/Desktop/ScalaTraining/hello.sc...
defined object hello
scala> hello.main(Array("Sara"))
Hello : Sara !
scala> val word = "India!"
word: String = India!
scala> var n = 5
n: Int = 5
scala> var i = 0
i: Int = 0
scala> while (i < n){
| println(word)
| i += 1
| }
India!
India!
India!
India!
India!
scala> (1 to n).foreach(x => println(word + " #" + x))
India! #1
India! #2
India! #3
India! #4
India! #5
$ cat Hello.scala
object Hello extends App{
println("Hello, World!")
}
scala> :load /home/hadoop/Desktop/ScalaTraining/Hello.scala
Loading /home/hadoop/Desktop/ScalaTraining/Hello.scala...
defined object Hello
scala> Hello.main(null)
Hello, World!
scala> 1 to n
res41: scala.collection.immutable.Range.Inclusive = Range(1, 2, 3, 4, 5)
scala> (1).to(5)
res42: scala.collection.immutable.Range.Inclusive = Range(1, 2, 3, 4, 5)
scala> val greetStrings : Array[String] = new Array[String](3)
greetStrings: Array[String] = Array(null, null, null)
scala> greetStrings(0) = "Hello"
scala> greetStrings(1) = ", "
scala> greetStrings(2) = " world! \n"
scala> greetStrings.apply(0)
res47: String = Hello
scala> def printArgs(args:Array[String]):Unit = {
| var i = 0
| while (i < args.length) {
| println(args(i))
| i += 1
| }
| }
printArgs: (args: Array[String])Unit
scala> printArgs(greetStrings)
Hello
,
world!
scala> printArgs(Array("I","Love","India"))
I
Love
India
scala> def printArgs(args:Array[String]): Unit = {
| for (arg < args)
:2: error: '<- br="" but="" expected="" found.="">for (arg < args)
^
scala> def printArgs(args:Array[String]): Unit = {
| for (arg <- args="" br=""> | println(arg)
| }
printArgs: (args: Array[String])Unit
scala> printArgs(greetStrings)
Hello
,
world!
scala> printArgs(Array("I","Love","India"))
I
Love
India
scala> Array("Siva "," Lara", " Mala").mkString("\t")
res56: String = Siva Lara Mala
scala> println(Array("Siva "," Lara", " Mala").mkString("\t"))
Siva Lara Mala
scala> println(Array(" Siva "," Lara", " Mala").mkString("\n"))
Siva
Lara
Mala
scala> println(Array(" Siva "," Lara", " Mala").mkString(":"))
Siva : Lara: Mala
scala> def formatArgs(args:Array[String]):String = return args.mkString("\n")
formatArgs: (args: Array[String])String
scala> formatArgs(Array("sare","gare"))
res63: String =
sare
gare
scala> formatArgs(Array("sare","gare")).foreach(println)
s
a
r
e
g
a
r
e
scala> myArray
res65: Array[String] = Array(Zara, Lara, Sara)
scala> formatArgs(myArray)
res66: String =
Zara
Lara
Sara
scala> def formatArgs(args:Array[String]):String = return args.mkString(":")
formatArgs: (args: Array[String])String
scala> formatArgs(myArray)
res67: String = Zara:Lara:Sara
scala> val res = formatArgs(Array("zero","one","two"))
res: String = zero:one:two
scala> assert(res == "zero:one:two")
scala> val numNames = Array("zero","one","two")
numNames: Array[String] = Array(zero, one, two)
scala> val numNames = Array.apply("zero","one","two")
numNames: Array[String] = Array(zero, one, two)
scala> numNames.exists(s => s.contains("z"))
res72: Boolean = true
scala> val oneTwo = List(1,2,3)
oneTwo: List[Int] = List(1, 2, 3)
scala> val threeFour = List(3,4)
threeFour: List[Int] = List(3, 4)
scala> val oneTwoThreeFour = oneTwo ::: threeFour
oneTwoThreeFour: List[Int] = List(1, 2, 3, 3, 4)
scala> val twoThree = List(2,3)
twoThree: List[Int] = List(2, 3)
scala> val oneTwoThree = 1 :: twoThree
oneTwoThree: List[Int] = List(1, 2, 3)
scala> val thrill = "will " :: "fill " :: "until " :: Nil
thrill: List[String] = List("will ", "fill ", "until ")
scala> thrill.head
res75: String = "will "
scala> thrill.length
res76: Int = 3
scala> thrill.last
res77: String = "until "
scala> val len = thrill.length
len: Int = 3
scala> thrill(len-1)
res78: String = "until "
scala> thrill
res85: List[String] = List("will ", "fill ", "until ")
scala> thrill.filter(x => x.contains("fill"))
res86: List[String] = List("fill ")
scala> thrill.filterNot(x => x.contains("fill"))
res87: List[String] = List("will ", "until ")
Partially applied functions:
-----------------------------
scala> def origFunc(a:Int, b:Int) = a+b
origFunc: (a: Int, b: Int)Int
scala> def modFunc = origFunc(10,_:Int)
modFunc: Int => Int
scala> modFunc(10)
res89: Int = 20
scala> modFunc(103)
res90: Int = 113
named parameters:
-----------------
scala> def speed(distance:Float, time:Float) = distance / time
speed: (distance: Float, time: Float)Float
scala> speed(time=4.5F, distance=10F)
res91: Float = 2.2222223
scala> speed(distance=100F,time=5.5F)
res92: Float = 18.181818
scala> thrill
res93: List[String] = List("will ", "fill ", "until ")
scala> thrill.sorted
res94: List[String] = List("fill ", "until ", "will ")
scala> thrill.map(s => s + "y")
res95: List[String] = List(will y, fill y, until y)
scala> thrill.map(s => s.trim() + "y")
res96: List[String] = List(willy, filly, untily)
scala> thrill
res99: List[String] = List("will ", "fill ", "until ")
scala> val thrill = List("I","Love","India")
thrill: List[String] = List(I, Love, India)
scala> val thrill = List("Will","Fill","Until")
thrill: List[String] = List(Will, Fill, Until)
scala> thrill.map(s => s + "y")
res100: List[String] = List(Willy, Filly, Untily)
scala> val thrill = "will" :: "will" :: "until" :: Nil
thrill: List[String] = List(will, will, until)
scala> thrill.map(s => s+ "y")
res0: List[String] = List(willy, willy, untily)
scala> thrill.mkString(",")
res1: String = will,will,until
scala> thrill.mkString("$")
res2: String = will$will$until
scala> thrill.mkString(":")
res3: String = will:will:until
scala> thrill.sortBy(s => s.charAt(0).toLower)
res7: List[String] = List(until, will, will)
scala> val pair = (99,"LuftBallons")
pair: (Int, String) = (99,LuftBallons)
scala> println(pair._1)
99
scala> println(pair._2)
LuftBallons
scala> val largeTuple = ('u','r',"the",1,4,"me")
largeTuple: (Char, Char, String, Int, Int, String) = (u,r,the,1,4,me)
// mutable Set example
scala> import scala.collection.mutable.Set
import scala.collection.mutable.Set
scala> val movieSet = Set("Hitch","Poltergeist")
movieSet: scala.collection.mutable.Set[String] = Set(Poltergeist, Hitch)
scala> movieSet += "Shrek"
res12: movieSet.type = Set(Poltergeist, Shrek, Hitch)
scala> println(movieSet)
Set(Poltergeist, Shrek, Hitch)
//Immutable Set Example
scala> import scala.collection.immutable.Set
import scala.collection.immutable.Set
scala> val movieSet = Set("Hitch","Poltergeist")
movieSet: scala.collection.immutable.Set[String] = Set(Hitch, Poltergeist)
scala> movieSet += "Shrek"
:29: error: value += is not a member of scala.collection.immutable.Set[String]
Expression does not convert to assignment because receiver is not assignable.
movieSet += "Shrek"
^
scala> println(movieSet)
Set(Hitch, Poltergeist)
scala> import scala.collection.mutable.Map
import scala.collection.mutable.Map
scala> val treasureMap = Map[Int,String]()
treasureMap: scala.collection.mutable.Map[Int,String] = Map()
scala> treasureMap += (1 -> "Go to Island")
res16: treasureMap.type = Map(1 -> Go to Island)
scala> treasureMap += (2 -> "Find Big X on Ground")
res17: treasureMap.type = Map(2 -> Find Big X on Ground, 1 -> Go to Island)
scala> treasureMap += (3 -> "Dig.")
res18: treasureMap.type = Map(2 -> Find Big X on Ground, 1 -> Go to Island, 3 -> Dig.)
scala> println(treasureMap)
Map(2 -> Find Big X on Ground, 1 -> Go to Island, 3 -> Dig.)
scala> treasureMap.foreach(println)
(2,Find Big X on Ground)
(1,Go to Island)
(3,Dig.)
//Immutable Map but val
scala> import scala.collection.immutable.Map
import scala.collection.immutable.Map
scala> val romanNumeral = Map(1 -> "I", 2 -> "II")
romanNumeral: scala.collection.immutable.Map[Int,String] = Map(1 -> I, 2 -> II)
scala> romanNumeral += (3 -> "III")
:32: error: value += is not a member of scala.collection.immutable.Map[Int,String]
Expression does not convert to assignment because receiver is not assignable.
romanNumeral += (3 -> "III")
^
//Immutable Map but var
scala> import scala.collection.immutable.Map
import scala.collection.immutable.Map
scala> var romanNumeral = Map(1->"I",2 -> "II")
romanNumeral: scala.collection.immutable.Map[Int,String] = Map(1 -> I, 2 -> II)
scala> romanNumeral += (3 -> "III")
scala> println(romanNumeral)
Map(1 -> I, 2 -> II, 3 -> III)
// Execption handling...
scala> def getContent(filePath:String) = {
| for(line <- br="" filepath="" getlines="" source.fromfile=""> | println(line.length + " " + line)
| }
getContent: (filePath: String)Unit
scala> getContent("")
java.io.FileNotFoundException: (No such file or directory)
at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(FileInputStream.java:195)
at java.io.FileInputStream.(FileInputStream.java:138)
at scala.io.Source$.fromFile(Source.scala:91)
at scala.io.Source$.fromFile(Source.scala:76)
at scala.io.Source$.fromFile(Source.scala:54)
at getContent(:37)
... 54 elided
scala> getContent("/home/hadoop/Desktop/emp_data.csv")
52 empno,ename,designation,manager,hire_date,sal,deptno
39 7369,SMITH,CLERK,7902,12/17/1980,800,20
42 7499,ALLEN,SALESMAN,7698,2/20/1981,1600,30
41 7521,WARD,SALESMAN,7698,2/22/1981,1250,30
41 7566,TURNER,MANAGER,7839,4/2/1981,2975,20
43 7654,MARTIN,SALESMAN,7698,9/28/1981,1250,30
41 7698,MILLER,MANAGER,7839,5/1/1981,2850,30
//Exception Handling
scala> def getContent(filePath:String) = {
| try{
| for (line <- br="" filepath="" getlines="" source.fromfile=""> | println(line.length + " " + line)
| }
| catch{
| case e: java.io.FileNotFoundException => println("No file found")
| }
| }
getContent: (filePath: String)Unit
scala> getContent("")
No file found
scala> getContent("/home/hadoop/Desktop/emp_Nosuchfile.csv")
No file found
//Partial functions
scala> def SalaryCalculator(base:Int, inc:Int, varComp:Int):Int = base + inc + varComp
SalaryCalculator: (base: Int, inc: Int, varComp: Int)Int
scala> def jrSalCalc = SalaryCalculator(10,_:Int,_:Int)
jrSalCalc: (Int, Int) => Int
scala> def MidSalCalc = SalaryCalculator(20,_:Int, _:Int)
MidSalCalc: (Int, Int) => Int
scala> def SeniorCalc = SalaryCalculator(30, _:Int, _:Int)
SeniorCalc: (Int, Int) => Int
scala> SalaryCalculator(35,10,12)
res0: Int = 57
scala> jrSalCalc(10,12)
res1: Int = 32
scala> MidSalCalc(10,12)
res2: Int = 42
scala> SeniorCalc(10,12)
res3: Int = 52
// named arguments
scala> def speed(distance:Float, time:Float) = distance / time
speed: (distance: Float, time: Float)Float
scala> def speed(distance:Float=10F, time:Float=2F) = distance / time
speed: (distance: Float, time: Float)Float
scala> speed(time=4F)
res5: Float = 2.5
scala> speed(10,4.5F)
res6: Float = 2.2222223
scala> speed(time=4.5F,distance=10F)
res7: Float = 2.2222223
scala> speed()
res8: Float = 5.0
scala> speed(distance=10F)
res9: Float = 5.0
scala> speed(distance=10F,time=4.5F)
res10: Float = 2.2222223
// Pattern matching example
scala> val myStr = "Hello"
myStr: String = Hello
scala> val result = myStr match {
case "Hello" => println("Greeting!")
case "Hi" => println("Short Greeting!")
case _ => println("Unknown")
}
Greeting!
result: Unit = ()
scala> val myStr = "Hello"
myStr: String = Hello
scala> val result = myStr match {
| case "Hello" => println("Greeting!")
| case "Hi" => println("Short Greeting!")
| case _ => println("Unknown")
| }
Greeting!
result: Unit = ()
scala> def UsingMatchPatternExa(myStr:String) = {
| val result = myStr match {
| case "Hello" => println("Greeting!")
| case "Hi" => println("Short Greeting!")
| case _ => println("Unknown")
| }
| }
UsingMatchPatternExa: (myStr: String)Unit
scala> UsingMatchPatternExa("Hello")
Greeting!
scala> UsingMatchPatternExa("Hi")
Short Greeting!
scala> UsingMatchPatternExa("Hey")
Unknown
scala> var a = 0
a: Int = 0
scala> var b = 0
b: Int = 0
scala> for (a <- 1="" 3="" b="" br="" to="" until=""> | println("Value of a : " + a + ", b: " + b)
| }
Value of a : 1, b: 1
Value of a : 1, b: 2
Value of a : 2, b: 1
Value of a : 2, b: 2
Value of a : 3, b: 1
Value of a : 3, b: 2
scala> val numList = List(1 to 10)
numList: List[scala.collection.immutable.Range.Inclusive] = List(Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
scala> for (a <- br="" numlist=""> | println("Value of a : " + a)
| }
Value of a : Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
scala> val numList = List(1 to 10)
numList: List[scala.collection.immutable.Range.Inclusive] = List(Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
scala> for (a <- br="" numlist=""> | println("Value of a : " + a)
| }
Value of a : Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
scala> val numList = List(1,2,3,4,5,6)
numList: List[Int] = List(1, 2, 3, 4, 5, 6)
scala> val retVal = numList.filter( x => x != 3 && x < 6)
retVal: List[Int] = List(1, 2, 4, 5)
scala> val retVal = for(a <- 3="" 6="" a="" br="" if="" numlist="" yield="">retVal: List[Int] = List(1, 2, 4, 5)
/// variable arguments
scala> def printStrings(args: String*) = {
| var i:Int = 0
| for (arg <- args="" br=""> | println("Arg Value[" + i + "] = " + arg)
| i = i + 1;
| }
| }
printStrings: (args: String*)Unit
scala> printStrings("Hadoop","Scala","Spark","Oozie","Hive","Hbase")
Arg Value[0] = Hadoop
Arg Value[1] = Scala
Arg Value[2] = Spark
Arg Value[3] = Oozie
Arg Value[4] = Hive
Arg Value[5] = Hbase
scala> printStrings("Arun","Prasad")
Arg Value[0] = Arun
Arg Value[1] = Prasad
// Anonymous functions
scala> var inc = (x: Int) => x + 1
inc: Int => Int =
scala>
scala> inc(7)
res3: Int = 8
scala> inc(7) - 10
res4: Int = -2
scala> var mul = (x:Int, y:Int) => x * y
mul: (Int, Int) => Int =
scala> mul(5,7)
res5: Int = 35
scala> var userDir = () => { System.getProperty("user.dir")}
userDir: () => String =
scala> println(userDir())
/home/hadoop
//Higher Order function0
//(x:A) --> x's type is A. So A is a type
//A means Any Type
scala> def apply(f:Int => String, v:Int) = f(v)
apply: (f: Int => String, v: Int)String
scala> def CurlyIt[A] (x: A) = "{" + x.toString() + "}"
CurlyIt: [A](x: A)String
scala> def SquareIt[A](x: A) = "[" + x.toString() + "]"
SquareIt: [A](x: A)String
scala> SquareIt(10)
res9: String = [10]
scala> CurlyIt(20)
res10: String = {20}
scala> println(apply(SquareIt,10))
[10]
scala> println(apply(CurlyIt,20))
{20}
scala> SquareIt("sare")
res14: String = [sare]
scala> CurlyIt("sare")
res15: String = {sare}
//Higher Order function
scala> def apply(f:String => String, v:String) = f(v)
apply: (f: String => String, v: String)String
scala> def CurlyIt[A] (x: A) = "{" + x.toString() + "}"
CurlyIt: [A](x: A)String
scala> def SquareIt[A](x: A) = "[" + x.toString() + "]"
SquareIt: [A](x: A)String
scala> println(apply(SquareIt,"--Sare--"))
[--Sare--]
scala> println(apply(CurlyIt,"--Sare--"))
{--Sare--}
// Partially applied function
scala> def adder (m:Int, n:Int, p:Int) = m + n + p
adder: (m: Int, n: Int, p: Int)Int
scala> val add2 = adder(2, _:Int, _:Int)
add2: (Int, Int) => Int =
scala> add2(10,2)
res19: Int = 14
scala> add2(1,1)
res20: Int = 4
scala> def adder(m:Int)(n:Int)(p:Int) = m + n + p
adder: (m: Int)(n: Int)(p: Int)Int
scala> adder(2)(3)(4)
res21: Int = 9
/*
Scala collections can be mutable and immutable
Mutable collections can be updated or extended in place.
Immutable collections never change: Additions, Removals, Updates operators return a new collection and leave the old collection unchanged
*/
Arrays :
Fixed size sequential collection of elements of the same type
Lists :
Sequential collection of elements of the same type
Immutable
Lists represents a Linked List
Sets
Maps
Tuples
Fixed number of items of different types together
Immutable
Option
scala> val myList = List(1,2,3)
myList: List[Int] = List(1, 2, 3)
scala> val ourList = 1 :: 2 :: 3 :: Nil
ourList: List[Int] = List(1, 2, 3)
// Add Leader -- Adding an element to the head of a list
scala> val AddLeaderList = 0 :: myList
AddLeaderList: List[Int] = List(0, 1, 2, 3)
//Add Follower -- Adding an element to the tail of a list
scala> val AddFollowerList = ourList :+ 4
AddFollowerList: List[Int] = List(1, 2, 3, 4)
// List concatenation
scala> val t3 = myList ::: ourList
t3: List[Int] = List(1, 2, 3, 1, 2, 3)
// remove duplicates
scala> t3.distinct
res23: List[Int] = List(1, 2, 3)
scala>
Left: List[String] = List(Arun, Banu, Chitra)
scala> val Right = List("Sara","Tanu","Umesh")
Right: List[String] = List(Sara, Tanu, Umesh)
scala> Left ::: Right
res27: List[String] = List(Arun, Banu, Chitra, Sara, Tanu, Umesh)
//List concatenation
scala> Right ::: Left
res28: List[String] = List(Sara, Tanu, Umesh, Arun, Banu, Chitra)
scala> Left.union(Right)
res30: List[String] = List(Arun, Banu, Chitra, Sara, Tanu, Umesh)
scala> Right.union(Left)
res31: List[String] = List(Sara, Tanu, Umesh, Arun, Banu, Chitra)
scala> val t = (10,"Twenty",30,"Fourty",true,3.5F)
t: (Int, String, Int, String, Boolean, Float) = (10,Twenty,30,Fourty,true,3.5)
scala> t._1
res35: Int = 10
//Sets
scala> val numberSet = Set(0,1,2,3,4,5,6,7,8, 9,10)
numberSet: scala.collection.immutable.Set[Int] = Set(0, 5, 10, 1, 6, 9, 2, 7, 3, 8, 4)
scala> numberSet.filter ( _ % 2 == 0)
res39: scala.collection.immutable.Set[Int] = Set(0, 10, 6, 2, 8, 4)
scala> numberSet.filter ( _ % 2 != 0)
res40: scala.collection.immutable.Set[Int] = Set(5, 1, 9, 7, 3)
// Set doesn't keep duplicates. It keeps unique only
scala> val noDuplicates = Set(1,2,3,2,3,1,2,3,4,3,2,1,2,34,5,4,3,2,1)
noDuplicates: scala.collection.immutable.Set[Int] = Set(5, 1, 2, 34, 3, 4)
scala> noDuplicates.foreach(println)
5
1
2
34
3
4
scala> def toInt(in : String) : Option[Int] = {
| try{
| Some(Integer.parseInt(in.trim))
| } catch {
| case e:NumberFormatException => None
| }
| }
toInt: (in: String)Option[Int]
scala> val someString = "123"
someString: String = 123
scala> toInt(someString) match {
| case Some(i) => println(i)
| case None => println(" Failed ")
| }
123
scala> val someString = "sare"
someString: String = sare
scala> toInt(someString) match {
| case Some(i) => println(i)
| case None => println(" Failed ")
| }
Failed
scala> toInt(someString).getOrElse(-1)
res44: Int = -1
scala> toInt("10101").getOrElse(-1)
res45: Int = 10101
scala> toInt("Aries").getOrElse("Format Error")
res47: Any = Format Error
scala> val countryCapitals = Map ("India"->"Delhi","Afhanistan"->"Kabul","Egypt"->"Cairo")
countryCapitals: scala.collection.immutable.Map[String,String] = Map(India -> Delhi, Afhanistan -> Kabul, Egypt -> Cairo)
scala> countryCapitals.get("Egypt")
res48: Option[String] = Some(Cairo)
scala> countryCapitals.get("Egypt").isDefined
res49: Boolean = true
scala> countryCapitals.get("China").getOrElse("Not Defined in our list")
res51: String = Not Defined in our list
// zip example
scala> val numbers = List(1,2,3,4,5)
numbers: List[Int] = List(1, 2, 3, 4, 5)
scala> val chars = List("a","b","c","d","e")
chars: List[String] = List(a, b, c, d, e)
scala> numbers.zip(chars)
res52: List[(Int, String)] = List((1,a), (2,b), (3,c), (4,d), (5,e))
scala> chars.zip(numbers)
res54: List[(String, Int)] = List((a,1), (b,2), (c,3), (d,4), (e,5))
// zipWithIndex example
scala> val myList = List("Arun","Prasad","Kalai","Harini","Nila","Silva")
myList: List[String] = List(Arun, Prasad, Kalai, Harini, Nila, Silva)
scala> myList.zipWithIndex
res55: List[(String, Int)] = List((Arun,0), (Prasad,1), (Kalai,2), (Harini,3), (Nila,4), (Silva,5))
scala> myList.zipWithIndex.foreach(println)
(Arun,0)
(Prasad,1)
(Kalai,2)
(Harini,3)
(Nila,4)
(Silva,5)
scala> myList.zip(List(1,2,3,4,5,6))
res57: List[(String, Int)] = List((Arun,1), (Prasad,2), (Kalai,3), (Harini,4), (Nila,5), (Silva,6))
scala> List(1,2,3,4,5,6).zip(myList)
res58: List[(Int, String)] = List((1,Arun), (2,Prasad), (3,Kalai), (4,Harini), (5,Nila), (6,Silva))
//fold left
scala> val numbers = List(1,2,3,4,5,6,7,8,9,10)
numbers: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
// with Seed value as 0
scala> numbers.foldLeft(0) { (m,n) => println("m : " + m + " n: " + n ); m + n}
m : 0 n: 1
m : 1 n: 2
m : 3 n: 3
m : 6 n: 4
m : 10 n: 5
m : 15 n: 6
m : 21 n: 7
m : 28 n: 8
m : 36 n: 9
m : 45 n: 10
res59: Int = 55
// with Seed value as 5
scala> numbers.foldLeft(5) { (m,n) => println("m : " + m + " n: " + n ); m + n}
m : 5 n: 1
m : 6 n: 2
m : 8 n: 3
m : 11 n: 4
m : 15 n: 5
m : 20 n: 6
m : 26 n: 7
m : 33 n: 8
m : 41 n: 9
m : 50 n: 10
res60: Int = 60
// fold Right
scala> val numbers = List(1,2,3,4,5,6,7,8,9,10)
numbers: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
scala> numbers.foldRight(0) { (m,n) => println("m : " + m + " n: " + n ); m + n}
m : 10 n: 0
m : 9 n: 10
m : 8 n: 19
m : 7 n: 27
m : 6 n: 34
m : 5 n: 40
m : 4 n: 45
m : 3 n: 49
m : 2 n: 52
m : 1 n: 54
res61: Int = 55
//with seed value as 5
scala> numbers.foldRight(5) { (m,n) => println("m : " + m + " n: " + n ); m + n}
m : 10 n: 5
m : 9 n: 15
m : 8 n: 24
m : 7 n: 32
m : 6 n: 39
m : 5 n: 45
m : 4 n: 50
m : 3 n: 54
m : 2 n: 57
m : 1 n: 59
res62: Int = 60
//flatten
//It collapses one level of nested structure
cala> List(List(1,2,3),List(3,4,5),List(5,6,7)).flatten
res63: List[Int] = List(1, 2, 3, 3, 4, 5, 5, 6, 7)
scala> List(List(1,2,3),List(3,4,5),List(5,6,7)).flatten.toSet
res64: scala.collection.immutable.Set[Int] = Set(5, 1, 6, 2, 7, 3, 4)
scala> List(List(1,2,3),List(3,4,5),List(5,6,7)).flatten.distinct
res65: List[Int] = List(1, 2, 3, 4, 5, 6, 7)
class Calculator(brand:String){
val color: String = if (brand =="TI"){
"blue"
} else if (brand =="HP"){
"black"
} else {
"white"
}
def add(m:Int, n:Int) : Int = m + n
def displayBrandAndColor()={
println("Brand : " + brand + ", Color : " + color)
}defined class Calculator
}
scala>
scala> val calc = new Calculator("HP")
calc: Calculator = Calculator@51d6e3ae
scala> println(calc.color)
black
cala> class Calculator(brand:String){
| val color: String = if (brand =="TI"){
| "blue"
| } else if (brand =="HP"){
| "black"
| } else {
| "white"
| }
| def add(m:Int, n:Int) : Int = m + n
| def displayBrandAndColor()={
| println("Brand : " + brand + ", Color : " + color)
| }
| }
defined class Calculator
scala> val c = new Calculator("HP")
c: Calculator = Calculator@67885e1f
scala> c.displayBrandAndColor
Brand : HP, Color : black
myIntArray: Array[Int] = Array(0, 0, 0)
scala> myIntArray
res0: Array[Int] = Array(0, 0, 0)
scala> myIntArray.foreach(println)
0
0
0
scala> myIntArray(0)=10
scala> myIntArray(1)=20
scala> myIntArray(2)=30
scala> myIntArray.foreach(println)
10
20
30
scala> def addOne(x:Int): Int = {
| x+1
| }
addOne: (x: Int)Int
scala> addOne(5)
res6: Int = 6
scala> addOne(50)
res7: Int = 51
scala> def addTwo(x:Int):Int = {
| return x + 2;
| }
addTwo: (x: Int)Int
scala> addTwo(5);
res8: Int = 7
scala> (1 to 10).foreach(x => println(addTwo(x)))
3
4
5
6
7
8
9
10
11
12
scala> def max(x:Int, y:Int): Int = {
| if (x > y) x else y
| }
max: (x: Int, y: Int)Int
scala> max(5,6)
res22: Int = 6
scala> val myArray = Array("Zara","Lara","Sara")
myArray: Array[String] = Array(Zara, Lara, Sara)
scala> var i = 0
i: Int = 0
scala> while (i < myArray.length) {
| println(myArray(i))
| i += 1
| }
Zara
Lara
Sara
scala> myArray.foreach(arg => println(arg))
Zara
Lara
Sara
scala> myArray.foreach(println(_))
Zara
Lara
Sara
scala> myArray.foreach(println)
Zara
Lara
Sara
scala> for(arg <- br="" myarray=""> | println(arg)
Zara
Lara
Sara
$ cat hello.sc
object hello{
def main(args:Array[String]):Unit = {
println("Hello : " + args(0) + " !")
}
}
scala> :load /home/hadoop/Desktop/ScalaTraining/hello.sc
Loading /home/hadoop/Desktop/ScalaTraining/hello.sc...
defined object hello
scala> hello.main(Array("Sara"))
Hello : Sara !
scala> val word = "India!"
word: String = India!
scala> var n = 5
n: Int = 5
scala> var i = 0
i: Int = 0
scala> while (i < n){
| println(word)
| i += 1
| }
India!
India!
India!
India!
India!
scala> (1 to n).foreach(x => println(word + " #" + x))
India! #1
India! #2
India! #3
India! #4
India! #5
$ cat Hello.scala
object Hello extends App{
println("Hello, World!")
}
scala> :load /home/hadoop/Desktop/ScalaTraining/Hello.scala
Loading /home/hadoop/Desktop/ScalaTraining/Hello.scala...
defined object Hello
scala> Hello.main(null)
Hello, World!
scala> 1 to n
res41: scala.collection.immutable.Range.Inclusive = Range(1, 2, 3, 4, 5)
scala> (1).to(5)
res42: scala.collection.immutable.Range.Inclusive = Range(1, 2, 3, 4, 5)
scala> val greetStrings : Array[String] = new Array[String](3)
greetStrings: Array[String] = Array(null, null, null)
scala> greetStrings(0) = "Hello"
scala> greetStrings(1) = ", "
scala> greetStrings(2) = " world! \n"
scala> greetStrings.apply(0)
res47: String = Hello
scala> def printArgs(args:Array[String]):Unit = {
| var i = 0
| while (i < args.length) {
| println(args(i))
| i += 1
| }
| }
printArgs: (args: Array[String])Unit
scala> printArgs(greetStrings)
Hello
,
world!
scala> printArgs(Array("I","Love","India"))
I
Love
India
scala> def printArgs(args:Array[String]): Unit = {
| for (arg < args)
^
scala> def printArgs(args:Array[String]): Unit = {
| for (arg <- args="" br=""> | println(arg)
| }
printArgs: (args: Array[String])Unit
scala> printArgs(greetStrings)
Hello
,
world!
scala> printArgs(Array("I","Love","India"))
I
Love
India
scala> Array("Siva "," Lara", " Mala").mkString("\t")
res56: String = Siva Lara Mala
scala> println(Array("Siva "," Lara", " Mala").mkString("\t"))
Siva Lara Mala
scala> println(Array(" Siva "," Lara", " Mala").mkString("\n"))
Siva
Lara
Mala
scala> println(Array(" Siva "," Lara", " Mala").mkString(":"))
Siva : Lara: Mala
scala> def formatArgs(args:Array[String]):String = return args.mkString("\n")
formatArgs: (args: Array[String])String
scala> formatArgs(Array("sare","gare"))
res63: String =
sare
gare
scala> formatArgs(Array("sare","gare")).foreach(println)
s
a
r
e
g
a
r
e
scala> myArray
res65: Array[String] = Array(Zara, Lara, Sara)
scala> formatArgs(myArray)
res66: String =
Zara
Lara
Sara
scala> def formatArgs(args:Array[String]):String = return args.mkString(":")
formatArgs: (args: Array[String])String
scala> formatArgs(myArray)
res67: String = Zara:Lara:Sara
scala> val res = formatArgs(Array("zero","one","two"))
res: String = zero:one:two
scala> assert(res == "zero:one:two")
scala> val numNames = Array("zero","one","two")
numNames: Array[String] = Array(zero, one, two)
scala> val numNames = Array.apply("zero","one","two")
numNames: Array[String] = Array(zero, one, two)
scala> numNames.exists(s => s.contains("z"))
res72: Boolean = true
scala> val oneTwo = List(1,2,3)
oneTwo: List[Int] = List(1, 2, 3)
scala> val threeFour = List(3,4)
threeFour: List[Int] = List(3, 4)
scala> val oneTwoThreeFour = oneTwo ::: threeFour
oneTwoThreeFour: List[Int] = List(1, 2, 3, 3, 4)
scala> val twoThree = List(2,3)
twoThree: List[Int] = List(2, 3)
scala> val oneTwoThree = 1 :: twoThree
oneTwoThree: List[Int] = List(1, 2, 3)
scala> val thrill = "will " :: "fill " :: "until " :: Nil
thrill: List[String] = List("will ", "fill ", "until ")
scala> thrill.head
res75: String = "will "
scala> thrill.length
res76: Int = 3
scala> thrill.last
res77: String = "until "
scala> val len = thrill.length
len: Int = 3
scala> thrill(len-1)
res78: String = "until "
scala> thrill
res85: List[String] = List("will ", "fill ", "until ")
scala> thrill.filter(x => x.contains("fill"))
res86: List[String] = List("fill ")
scala> thrill.filterNot(x => x.contains("fill"))
res87: List[String] = List("will ", "until ")
Partially applied functions:
-----------------------------
scala> def origFunc(a:Int, b:Int) = a+b
origFunc: (a: Int, b: Int)Int
scala> def modFunc = origFunc(10,_:Int)
modFunc: Int => Int
scala> modFunc(10)
res89: Int = 20
scala> modFunc(103)
res90: Int = 113
named parameters:
-----------------
scala> def speed(distance:Float, time:Float) = distance / time
speed: (distance: Float, time: Float)Float
scala> speed(time=4.5F, distance=10F)
res91: Float = 2.2222223
scala> speed(distance=100F,time=5.5F)
res92: Float = 18.181818
scala> thrill
res93: List[String] = List("will ", "fill ", "until ")
scala> thrill.sorted
res94: List[String] = List("fill ", "until ", "will ")
scala> thrill.map(s => s + "y")
res95: List[String] = List(will y, fill y, until y)
scala> thrill.map(s => s.trim() + "y")
res96: List[String] = List(willy, filly, untily)
scala> thrill
res99: List[String] = List("will ", "fill ", "until ")
scala> val thrill = List("I","Love","India")
thrill: List[String] = List(I, Love, India)
scala> val thrill = List("Will","Fill","Until")
thrill: List[String] = List(Will, Fill, Until)
scala> thrill.map(s => s + "y")
res100: List[String] = List(Willy, Filly, Untily)
scala> val thrill = "will" :: "will" :: "until" :: Nil
thrill: List[String] = List(will, will, until)
scala> thrill.map(s => s+ "y")
res0: List[String] = List(willy, willy, untily)
scala> thrill.mkString(",")
res1: String = will,will,until
scala> thrill.mkString("$")
res2: String = will$will$until
scala> thrill.mkString(":")
res3: String = will:will:until
scala> thrill.sortBy(s => s.charAt(0).toLower)
res7: List[String] = List(until, will, will)
scala> val pair = (99,"LuftBallons")
pair: (Int, String) = (99,LuftBallons)
scala> println(pair._1)
99
scala> println(pair._2)
LuftBallons
scala> val largeTuple = ('u','r',"the",1,4,"me")
largeTuple: (Char, Char, String, Int, Int, String) = (u,r,the,1,4,me)
// mutable Set example
scala> import scala.collection.mutable.Set
import scala.collection.mutable.Set
scala> val movieSet = Set("Hitch","Poltergeist")
movieSet: scala.collection.mutable.Set[String] = Set(Poltergeist, Hitch)
scala> movieSet += "Shrek"
res12: movieSet.type = Set(Poltergeist, Shrek, Hitch)
scala> println(movieSet)
Set(Poltergeist, Shrek, Hitch)
//Immutable Set Example
scala> import scala.collection.immutable.Set
import scala.collection.immutable.Set
scala> val movieSet = Set("Hitch","Poltergeist")
movieSet: scala.collection.immutable.Set[String] = Set(Hitch, Poltergeist)
scala> movieSet += "Shrek"
Expression does not convert to assignment because receiver is not assignable.
movieSet += "Shrek"
^
scala> println(movieSet)
Set(Hitch, Poltergeist)
scala> import scala.collection.mutable.Map
import scala.collection.mutable.Map
scala> val treasureMap = Map[Int,String]()
treasureMap: scala.collection.mutable.Map[Int,String] = Map()
scala> treasureMap += (1 -> "Go to Island")
res16: treasureMap.type = Map(1 -> Go to Island)
scala> treasureMap += (2 -> "Find Big X on Ground")
res17: treasureMap.type = Map(2 -> Find Big X on Ground, 1 -> Go to Island)
scala> treasureMap += (3 -> "Dig.")
res18: treasureMap.type = Map(2 -> Find Big X on Ground, 1 -> Go to Island, 3 -> Dig.)
scala> println(treasureMap)
Map(2 -> Find Big X on Ground, 1 -> Go to Island, 3 -> Dig.)
scala> treasureMap.foreach(println)
(2,Find Big X on Ground)
(1,Go to Island)
(3,Dig.)
//Immutable Map but val
scala> import scala.collection.immutable.Map
import scala.collection.immutable.Map
scala> val romanNumeral = Map(1 -> "I", 2 -> "II")
romanNumeral: scala.collection.immutable.Map[Int,String] = Map(1 -> I, 2 -> II)
scala> romanNumeral += (3 -> "III")
Expression does not convert to assignment because receiver is not assignable.
romanNumeral += (3 -> "III")
^
//Immutable Map but var
scala> import scala.collection.immutable.Map
import scala.collection.immutable.Map
scala> var romanNumeral = Map(1->"I",2 -> "II")
romanNumeral: scala.collection.immutable.Map[Int,String] = Map(1 -> I, 2 -> II)
scala> romanNumeral += (3 -> "III")
scala> println(romanNumeral)
Map(1 -> I, 2 -> II, 3 -> III)
// Execption handling...
scala> def getContent(filePath:String) = {
| for(line <- br="" filepath="" getlines="" source.fromfile=""> | println(line.length + " " + line)
| }
getContent: (filePath: String)Unit
scala> getContent("")
java.io.FileNotFoundException: (No such file or directory)
at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(FileInputStream.java:195)
at java.io.FileInputStream.
at scala.io.Source$.fromFile(Source.scala:91)
at scala.io.Source$.fromFile(Source.scala:76)
at scala.io.Source$.fromFile(Source.scala:54)
at getContent(
... 54 elided
scala> getContent("/home/hadoop/Desktop/emp_data.csv")
52 empno,ename,designation,manager,hire_date,sal,deptno
39 7369,SMITH,CLERK,7902,12/17/1980,800,20
42 7499,ALLEN,SALESMAN,7698,2/20/1981,1600,30
41 7521,WARD,SALESMAN,7698,2/22/1981,1250,30
41 7566,TURNER,MANAGER,7839,4/2/1981,2975,20
43 7654,MARTIN,SALESMAN,7698,9/28/1981,1250,30
41 7698,MILLER,MANAGER,7839,5/1/1981,2850,30
//Exception Handling
scala> def getContent(filePath:String) = {
| try{
| for (line <- br="" filepath="" getlines="" source.fromfile=""> | println(line.length + " " + line)
| }
| catch{
| case e: java.io.FileNotFoundException => println("No file found")
| }
| }
getContent: (filePath: String)Unit
scala> getContent("")
No file found
scala> getContent("/home/hadoop/Desktop/emp_Nosuchfile.csv")
No file found
//Partial functions
scala> def SalaryCalculator(base:Int, inc:Int, varComp:Int):Int = base + inc + varComp
SalaryCalculator: (base: Int, inc: Int, varComp: Int)Int
scala> def jrSalCalc = SalaryCalculator(10,_:Int,_:Int)
jrSalCalc: (Int, Int) => Int
scala> def MidSalCalc = SalaryCalculator(20,_:Int, _:Int)
MidSalCalc: (Int, Int) => Int
scala> def SeniorCalc = SalaryCalculator(30, _:Int, _:Int)
SeniorCalc: (Int, Int) => Int
scala> SalaryCalculator(35,10,12)
res0: Int = 57
scala> jrSalCalc(10,12)
res1: Int = 32
scala> MidSalCalc(10,12)
res2: Int = 42
scala> SeniorCalc(10,12)
res3: Int = 52
// named arguments
scala> def speed(distance:Float, time:Float) = distance / time
speed: (distance: Float, time: Float)Float
scala> def speed(distance:Float=10F, time:Float=2F) = distance / time
speed: (distance: Float, time: Float)Float
scala> speed(time=4F)
res5: Float = 2.5
scala> speed(10,4.5F)
res6: Float = 2.2222223
scala> speed(time=4.5F,distance=10F)
res7: Float = 2.2222223
scala> speed()
res8: Float = 5.0
scala> speed(distance=10F)
res9: Float = 5.0
scala> speed(distance=10F,time=4.5F)
res10: Float = 2.2222223
// Pattern matching example
scala> val myStr = "Hello"
myStr: String = Hello
scala> val result = myStr match {
case "Hello" => println("Greeting!")
case "Hi" => println("Short Greeting!")
case _ => println("Unknown")
}
Greeting!
result: Unit = ()
scala> val myStr = "Hello"
myStr: String = Hello
scala> val result = myStr match {
| case "Hello" => println("Greeting!")
| case "Hi" => println("Short Greeting!")
| case _ => println("Unknown")
| }
Greeting!
result: Unit = ()
scala> def UsingMatchPatternExa(myStr:String) = {
| val result = myStr match {
| case "Hello" => println("Greeting!")
| case "Hi" => println("Short Greeting!")
| case _ => println("Unknown")
| }
| }
UsingMatchPatternExa: (myStr: String)Unit
scala> UsingMatchPatternExa("Hello")
Greeting!
scala> UsingMatchPatternExa("Hi")
Short Greeting!
scala> UsingMatchPatternExa("Hey")
Unknown
scala> var a = 0
a: Int = 0
scala> var b = 0
b: Int = 0
scala> for (a <- 1="" 3="" b="" br="" to="" until=""> | println("Value of a : " + a + ", b: " + b)
| }
Value of a : 1, b: 1
Value of a : 1, b: 2
Value of a : 2, b: 1
Value of a : 2, b: 2
Value of a : 3, b: 1
Value of a : 3, b: 2
scala> val numList = List(1 to 10)
numList: List[scala.collection.immutable.Range.Inclusive] = List(Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
scala> for (a <- br="" numlist=""> | println("Value of a : " + a)
| }
Value of a : Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
scala> val numList = List(1 to 10)
numList: List[scala.collection.immutable.Range.Inclusive] = List(Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
scala> for (a <- br="" numlist=""> | println("Value of a : " + a)
| }
Value of a : Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
scala> val numList = List(1,2,3,4,5,6)
numList: List[Int] = List(1, 2, 3, 4, 5, 6)
scala> val retVal = numList.filter( x => x != 3 && x < 6)
retVal: List[Int] = List(1, 2, 4, 5)
scala> val retVal = for(a <- 3="" 6="" a="" br="" if="" numlist="" yield="">retVal: List[Int] = List(1, 2, 4, 5)
/// variable arguments
scala> def printStrings(args: String*) = {
| var i:Int = 0
| for (arg <- args="" br=""> | println("Arg Value[" + i + "] = " + arg)
| i = i + 1;
| }
| }
printStrings: (args: String*)Unit
scala> printStrings("Hadoop","Scala","Spark","Oozie","Hive","Hbase")
Arg Value[0] = Hadoop
Arg Value[1] = Scala
Arg Value[2] = Spark
Arg Value[3] = Oozie
Arg Value[4] = Hive
Arg Value[5] = Hbase
scala> printStrings("Arun","Prasad")
Arg Value[0] = Arun
Arg Value[1] = Prasad
// Anonymous functions
scala> var inc = (x: Int) => x + 1
inc: Int => Int =
scala>
scala> inc(7)
res3: Int = 8
scala> inc(7) - 10
res4: Int = -2
scala> var mul = (x:Int, y:Int) => x * y
mul: (Int, Int) => Int =
scala> mul(5,7)
res5: Int = 35
scala> var userDir = () => { System.getProperty("user.dir")}
userDir: () => String =
scala> println(userDir())
/home/hadoop
//Higher Order function0
//(x:A) --> x's type is A. So A is a type
//A means Any Type
scala> def apply(f:Int => String, v:Int) = f(v)
apply: (f: Int => String, v: Int)String
scala> def CurlyIt[A] (x: A) = "{" + x.toString() + "}"
CurlyIt: [A](x: A)String
scala> def SquareIt[A](x: A) = "[" + x.toString() + "]"
SquareIt: [A](x: A)String
scala> SquareIt(10)
res9: String = [10]
scala> CurlyIt(20)
res10: String = {20}
scala> println(apply(SquareIt,10))
[10]
scala> println(apply(CurlyIt,20))
{20}
scala> SquareIt("sare")
res14: String = [sare]
scala> CurlyIt("sare")
res15: String = {sare}
//Higher Order function
scala> def apply(f:String => String, v:String) = f(v)
apply: (f: String => String, v: String)String
scala> def CurlyIt[A] (x: A) = "{" + x.toString() + "}"
CurlyIt: [A](x: A)String
scala> def SquareIt[A](x: A) = "[" + x.toString() + "]"
SquareIt: [A](x: A)String
scala> println(apply(SquareIt,"--Sare--"))
[--Sare--]
scala> println(apply(CurlyIt,"--Sare--"))
{--Sare--}
// Partially applied function
scala> def adder (m:Int, n:Int, p:Int) = m + n + p
adder: (m: Int, n: Int, p: Int)Int
scala> val add2 = adder(2, _:Int, _:Int)
add2: (Int, Int) => Int =
scala> add2(10,2)
res19: Int = 14
scala> add2(1,1)
res20: Int = 4
scala> def adder(m:Int)(n:Int)(p:Int) = m + n + p
adder: (m: Int)(n: Int)(p: Int)Int
scala> adder(2)(3)(4)
res21: Int = 9
/*
Scala collections can be mutable and immutable
Mutable collections can be updated or extended in place.
Immutable collections never change: Additions, Removals, Updates operators return a new collection and leave the old collection unchanged
*/
Arrays :
Fixed size sequential collection of elements of the same type
Lists :
Sequential collection of elements of the same type
Immutable
Lists represents a Linked List
Sets
Maps
Tuples
Fixed number of items of different types together
Immutable
Option
scala> val myList = List(1,2,3)
myList: List[Int] = List(1, 2, 3)
scala> val ourList = 1 :: 2 :: 3 :: Nil
ourList: List[Int] = List(1, 2, 3)
// Add Leader -- Adding an element to the head of a list
scala> val AddLeaderList = 0 :: myList
AddLeaderList: List[Int] = List(0, 1, 2, 3)
//Add Follower -- Adding an element to the tail of a list
scala> val AddFollowerList = ourList :+ 4
AddFollowerList: List[Int] = List(1, 2, 3, 4)
// List concatenation
scala> val t3 = myList ::: ourList
t3: List[Int] = List(1, 2, 3, 1, 2, 3)
// remove duplicates
scala> t3.distinct
res23: List[Int] = List(1, 2, 3)
scala>
Left: List[String] = List(Arun, Banu, Chitra)
scala> val Right = List("Sara","Tanu","Umesh")
Right: List[String] = List(Sara, Tanu, Umesh)
scala> Left ::: Right
res27: List[String] = List(Arun, Banu, Chitra, Sara, Tanu, Umesh)
//List concatenation
scala> Right ::: Left
res28: List[String] = List(Sara, Tanu, Umesh, Arun, Banu, Chitra)
scala> Left.union(Right)
res30: List[String] = List(Arun, Banu, Chitra, Sara, Tanu, Umesh)
scala> Right.union(Left)
res31: List[String] = List(Sara, Tanu, Umesh, Arun, Banu, Chitra)
scala> val t = (10,"Twenty",30,"Fourty",true,3.5F)
t: (Int, String, Int, String, Boolean, Float) = (10,Twenty,30,Fourty,true,3.5)
scala> t._1
res35: Int = 10
//Sets
scala> val numberSet = Set(0,1,2,3,4,5,6,7,8, 9,10)
numberSet: scala.collection.immutable.Set[Int] = Set(0, 5, 10, 1, 6, 9, 2, 7, 3, 8, 4)
scala> numberSet.filter ( _ % 2 == 0)
res39: scala.collection.immutable.Set[Int] = Set(0, 10, 6, 2, 8, 4)
scala> numberSet.filter ( _ % 2 != 0)
res40: scala.collection.immutable.Set[Int] = Set(5, 1, 9, 7, 3)
// Set doesn't keep duplicates. It keeps unique only
scala> val noDuplicates = Set(1,2,3,2,3,1,2,3,4,3,2,1,2,34,5,4,3,2,1)
noDuplicates: scala.collection.immutable.Set[Int] = Set(5, 1, 2, 34, 3, 4)
scala> noDuplicates.foreach(println)
5
1
2
34
3
4
scala> def toInt(in : String) : Option[Int] = {
| try{
| Some(Integer.parseInt(in.trim))
| } catch {
| case e:NumberFormatException => None
| }
| }
toInt: (in: String)Option[Int]
scala> val someString = "123"
someString: String = 123
scala> toInt(someString) match {
| case Some(i) => println(i)
| case None => println(" Failed ")
| }
123
scala> val someString = "sare"
someString: String = sare
scala> toInt(someString) match {
| case Some(i) => println(i)
| case None => println(" Failed ")
| }
Failed
scala> toInt(someString).getOrElse(-1)
res44: Int = -1
scala> toInt("10101").getOrElse(-1)
res45: Int = 10101
scala> toInt("Aries").getOrElse("Format Error")
res47: Any = Format Error
scala> val countryCapitals = Map ("India"->"Delhi","Afhanistan"->"Kabul","Egypt"->"Cairo")
countryCapitals: scala.collection.immutable.Map[String,String] = Map(India -> Delhi, Afhanistan -> Kabul, Egypt -> Cairo)
scala> countryCapitals.get("Egypt")
res48: Option[String] = Some(Cairo)
scala> countryCapitals.get("Egypt").isDefined
res49: Boolean = true
scala> countryCapitals.get("China").getOrElse("Not Defined in our list")
res51: String = Not Defined in our list
// zip example
scala> val numbers = List(1,2,3,4,5)
numbers: List[Int] = List(1, 2, 3, 4, 5)
scala> val chars = List("a","b","c","d","e")
chars: List[String] = List(a, b, c, d, e)
scala> numbers.zip(chars)
res52: List[(Int, String)] = List((1,a), (2,b), (3,c), (4,d), (5,e))
scala> chars.zip(numbers)
res54: List[(String, Int)] = List((a,1), (b,2), (c,3), (d,4), (e,5))
// zipWithIndex example
scala> val myList = List("Arun","Prasad","Kalai","Harini","Nila","Silva")
myList: List[String] = List(Arun, Prasad, Kalai, Harini, Nila, Silva)
scala> myList.zipWithIndex
res55: List[(String, Int)] = List((Arun,0), (Prasad,1), (Kalai,2), (Harini,3), (Nila,4), (Silva,5))
scala> myList.zipWithIndex.foreach(println)
(Arun,0)
(Prasad,1)
(Kalai,2)
(Harini,3)
(Nila,4)
(Silva,5)
scala> myList.zip(List(1,2,3,4,5,6))
res57: List[(String, Int)] = List((Arun,1), (Prasad,2), (Kalai,3), (Harini,4), (Nila,5), (Silva,6))
scala> List(1,2,3,4,5,6).zip(myList)
res58: List[(Int, String)] = List((1,Arun), (2,Prasad), (3,Kalai), (4,Harini), (5,Nila), (6,Silva))
//fold left
scala> val numbers = List(1,2,3,4,5,6,7,8,9,10)
numbers: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
// with Seed value as 0
scala> numbers.foldLeft(0) { (m,n) => println("m : " + m + " n: " + n ); m + n}
m : 0 n: 1
m : 1 n: 2
m : 3 n: 3
m : 6 n: 4
m : 10 n: 5
m : 15 n: 6
m : 21 n: 7
m : 28 n: 8
m : 36 n: 9
m : 45 n: 10
res59: Int = 55
// with Seed value as 5
scala> numbers.foldLeft(5) { (m,n) => println("m : " + m + " n: " + n ); m + n}
m : 5 n: 1
m : 6 n: 2
m : 8 n: 3
m : 11 n: 4
m : 15 n: 5
m : 20 n: 6
m : 26 n: 7
m : 33 n: 8
m : 41 n: 9
m : 50 n: 10
res60: Int = 60
// fold Right
scala> val numbers = List(1,2,3,4,5,6,7,8,9,10)
numbers: List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
scala> numbers.foldRight(0) { (m,n) => println("m : " + m + " n: " + n ); m + n}
m : 10 n: 0
m : 9 n: 10
m : 8 n: 19
m : 7 n: 27
m : 6 n: 34
m : 5 n: 40
m : 4 n: 45
m : 3 n: 49
m : 2 n: 52
m : 1 n: 54
res61: Int = 55
//with seed value as 5
scala> numbers.foldRight(5) { (m,n) => println("m : " + m + " n: " + n ); m + n}
m : 10 n: 5
m : 9 n: 15
m : 8 n: 24
m : 7 n: 32
m : 6 n: 39
m : 5 n: 45
m : 4 n: 50
m : 3 n: 54
m : 2 n: 57
m : 1 n: 59
res62: Int = 60
//flatten
//It collapses one level of nested structure
cala> List(List(1,2,3),List(3,4,5),List(5,6,7)).flatten
res63: List[Int] = List(1, 2, 3, 3, 4, 5, 5, 6, 7)
scala> List(List(1,2,3),List(3,4,5),List(5,6,7)).flatten.toSet
res64: scala.collection.immutable.Set[Int] = Set(5, 1, 6, 2, 7, 3, 4)
scala> List(List(1,2,3),List(3,4,5),List(5,6,7)).flatten.distinct
res65: List[Int] = List(1, 2, 3, 4, 5, 6, 7)
class Calculator(brand:String){
val color: String = if (brand =="TI"){
"blue"
} else if (brand =="HP"){
"black"
} else {
"white"
}
def add(m:Int, n:Int) : Int = m + n
def displayBrandAndColor()={
println("Brand : " + brand + ", Color : " + color)
}defined class Calculator
}
scala>
scala> val calc = new Calculator("HP")
calc: Calculator = Calculator@51d6e3ae
scala> println(calc.color)
black
cala> class Calculator(brand:String){
| val color: String = if (brand =="TI"){
| "blue"
| } else if (brand =="HP"){
| "black"
| } else {
| "white"
| }
| def add(m:Int, n:Int) : Int = m + n
| def displayBrandAndColor()={
| println("Brand : " + brand + ", Color : " + color)
| }
| }
defined class Calculator
scala> val c = new Calculator("HP")
c: Calculator = Calculator@67885e1f
scala> c.displayBrandAndColor
Brand : HP, Color : black
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