scala

- right triangle pythagorean theorem solver
  solve for a, b, or c

    // solve c
    printRT(solveRT(3, 4))  // 3, 4, 5

    val r = new rt(3, 4)
    r.print               // 3, 4, 0
    r.solve.print         // 3, 4, 5

    // solve a
    new rt(0, 12, 13).solve.print  // 5, 12, 13

    // solve b, read line, space delimited no commas
    val r = inputRT  // 7 0  25
    r.solve.print    // 7, 24, 25

    // solve c, a = b
    var r = new rt(2)
    r.print            // 2, 2, 0
    r.solve.print      // 2, 2, 2.8284271247461903

    (inputRT).solve.print  // 2 => 2, 2, 2.8284271247461903

    // scale
    new rt(2).solve.scale(2).print  // 4, 4, 5.656854249492381
    new rt(2).solve.halve.print     // 1, 1, 1.4142135623730951


      // :paste into repl

      import math._

      type rt = RightTriangle
      class RightTriangle(val a:Double = 0, private var _b:Double = 0, val c:Double = 0)
      {
          def b = _b
          _b = if (_b + c == 0) a else _b

          def solve(): RightTriangle =
          {
              solveRT(this.a, this.b, this.c)
          }

          def print() =
          {
              printRT(this)
          }

          def scale(aScale:Double): RightTriangle =
          {
              scaleRT(this, aScale)
          }

          def halve(): RightTriangle =
          {
             halveRT(this)
          }
      }

      // lib
      def solveRT(rt:RightTriangle): RightTriangle =
      {
          solveRT(rt.a, rt.b, rt.c)
      }
      
      def solveRT(a:Double, _b:Double = 0, c:Double = 0): RightTriangle =
      {
              def fx(hyp:Double, leg:Double): Double =
              {
                  sqrt(pow(hyp, 2) - pow(leg, 2))
              }

          val b = if (_b + c == 0) a else _b

          (a, b, c) match
          {
              case (0, _, _) => new RightTriangle(fx(c, b), b, c)     // solve a
              case (_, 0, _) => new RightTriangle(a, fx(c, a), c)     //       b
              case _         => new RightTriangle(a, b, hypot(a, b))  //       c
          }
      }

      def halveRT(rt:RightTriangle): RightTriangle =
      {
          scaleRT(rt, 0.5)
      }

      def inputRT: RightTriangle =
      {
          val input:String = io.StdIn.readLine()
          val rt:Array[Double] = input.trim().replaceAll(" +", " ").split(" ").map(_.toDouble)

          rt.length match
          {
              case 1 => new RightTriangle(rt(0))
              case 2 => new RightTriangle(rt(0), rt(1))
              case 3 => new RightTriangle(rt(0), rt(1), rt(2))
          }
      }
      def irt = inputRT

      def printRT(rt:RightTriangle)
      {
          println(f"a: ${rt.a}\nb: ${rt.b}\nc: ${rt.c}")
      }

      def scaleRT(rt:RightTriangle, scale:Double) =
      {
          new RightTriangle(rt.a * scale, rt.b * scale, rt.c * scale)
      }


- file io
  number lines

    import java.io._  // PrintWriter

    val inFile  = io.Source.fromFile("/users/lc/file.txt")
    val outFile = new PrintWriter(new File("/users/lc/file.txt.out"))

    var i = 0
    for (line <- inFile.getLines()) {
        i += 1
        println(s"$i. $line")
        outFile.write("%d. %s\n".format(i, line))
    }
    outFile.close
    inFile.close


- misc

    scala.util.Properties.versionString  // 2.12.1

    val guid = java.util.UUID.randomUUID
    guid.toString().filter(!"-".contains(_))
    guid.toString().toUpperCase()

    "foo bar".getBytes             // Array[Byte] = Array(102, 111, 111, 32, 98, 97, 114)
    "scala".intersect("language")  // String = ala
    "FOO".toLowerCase()

    1.to(10).foreach (print)
    1.to(10).foreach (println)
    1.to(10).foreach {x => println(x + ".")}

    1.to(10).map(_ * 2)              // scala.collection.immutable.IndexedSeq[Int] = Vector(2, 4, 6, 8, 10, 12, 14, 16, 18, 20)
    List(1, 2, 3, 4, 5).map(_ * 10)  // List[Int] = List(10, 20, 30, 40, 50)

    val d = new java.util.Date  // Wed Nov 12 08:50:00 MST 2014

    math.pow(3, 2)
    import math._
    pow(3, 2)
    hypot(3, 4)  // Double = 5.0

    (90:Double).toRadians         // Double = 1.5707963267948966
    1.5707963267948966.toDegrees  // Double = 90.0

    (122:Float)/255   // 0.47843137
    (122:Double)/255  // 0.47843137254901963
    122/255.0         // 0.47843137254901963

    "decode%20url".replaceAll("%20", " ")

    val a:Double = 2.0
    println(s"a: $a")      // 2.0
    println(f"a: $a")      // 2.0
    println(f"a: $a%g")    // 2.00000
    println(f"a: $a%.1g")  // 2
    println(f"a: $a%.2g")  // 2.0
    println(f"a: $a%.3g")  // 2.00


- java

    java -version  # 12.0.1, 04-16-2019
                   # /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java
                   # temp files: /Users/*/Library/Application Support/Oracle/Java/Deployment/cache

    // javac Hello.java
    // java Hello
    // 
    public class Hello {
        
        public static void main(String[] args) {
            
            System.out.println("hello Java");
        
        }
        
    }