实验 2 Scala 编程初级实践

// 在 spark-shell 提示符下直接粘贴即可
import scala.io.StdInval q = StdIn.readLine("请输入 q: ").trim.toDoublevar n   = 1
var sn  = 0.0
var term = 0.0while (sn < q) {term = (n + 1).toDouble / nsn  += termn   += 1
}println(f"Sn=$sn%.6f")

// ========= 1. 基础定义（题目已给出，顺手修掉笔误） =========
case class Point(var x: Double, var y: Double) extends Drawable {def shift(deltaX: Double, deltaY: Double): Unit = { x += deltaX; y += deltaY }override def toString: String = s"($x,$y)"
}trait Drawable {def draw(): Unit = println(this.toString)
}// ========= 2. 抽象基类 =========
abstract class Shape(var pos: Point) extends Drawable {def moveTo(newPos: Point): Unit = { pos = newPos }def zoom(factor: Double): Unit
}// ========= 3. 直线 =========
class Line(var p1: Point, var p2: Point) extends Shape(p1) with Drawable {/* 中点 */private def mid: Point =Point((p1.x + p2.x) / 2, (p1.y + p2.y) / 2)/* 以中点为基准缩放 factor 倍 */override def zoom(factor: Double): Unit = {val m = midp1.x = m.x + (p1.x - m.x) * factorp1.y = m.y + (p1.y - m.y) * factorp2.x = m.x + (p2.x - m.x) * factorp2.y = m.y + (p2.y - m.y) * factor}/* 移动：保持向量不变，整体平移 */override def moveTo(newPos: Point): Unit = {val dx = newPos.x - p1.xval dy = newPos.y - p1.yp1.shift(dx, dy)p2.shift(dx, dy)}override def toString: String = s"Line: $p1--$p2"override def draw(): Unit = println(toString)
}// ========= 4. 圆 =========
class Circle(center: Point, var radius: Double)extends Shape(center) with Drawable {override def zoom(factor: Double): Unit = radius *= factoroverride def toString: String = s"Circle center: $pos,R=$radius"override def draw(): Unit = println(toString)
}// ========= 5. 入口 =========
object MyDraw {def main(args: Array[String]): Unit = {val p = new Point(10, 30)p.drawval line1 = new Line(Point(0, 0), Point(20, 20))line1.drawline1.moveTo(Point(5, 5))line1.drawline1.zoom(2)line1.drawval cir = new Circle(Point(10, 10), 5)cir.drawcir.moveTo(Point(30, 20))cir.drawcir.zoom(0.5)cir.draw}
}// ========= 6. 在 spark-shell 里跑起来 =========
MyDraw.main(Array.empty)

object GradeStatistics {private case class Student(id: String, gender: String, scores: Map[String, Double])// 从字符串解析数据private def parseData(data: String): (List[Student], List[String]) = {val lines = data.linesIterator.map(_.trim).filter(_.nonEmpty).toListif (lines.length < 2) return (Nil, Nil)// 解析表头val header = lines.head.split("\\s+").toListval courses = header.drop(2)// 解析学生数据val students = lines.tail.map { line =>val fields = line.split("\\s+")val id = fields(0)val gender = fields(1)val scores = (courses zip fields.drop(2).map(_.toDouble)).toMapStudent(id, gender, scores)}(students, courses)}// 统计单个组private def calculateStats(students: List[Student], courses: List[String]):Map[String, (Double, Double, Double)] = {courses.map { course =>val scores = students.map(_.scores(course))val avg = scores.sum / scores.sizeval min = scores.minval max = scores.maxcourse -> (avg, min, max)}.toMap}// 打印统计结果private def printStats(title: String, stats: Map[String, (Double, Double, Double)]): Unit = {println(title)println("course    average   min   max")stats.foreach { case (course, (avg, min, max)) =>println(f"$course:     $avg%5.2f   $min%5.2f   $max%5.2f")}println()}// 主处理函数def analyze(data: String): Unit = {val (students, courses) = parseData(data)if (students.isEmpty) {println("没有学生数据")return}println(s"共读取 ${students.size} 名学生数据")println(s"课程：${courses.mkString(", ")}")println("-" * 40)// 所有学生统计val overallStats = calculateStats(students, courses)printStats("所有学生成绩统计：", overallStats)// 男生统计val maleStats = calculateStats(students.filter(_.gender == "male"), courses)printStats("男生成绩统计：", maleStats)// 女生统计val femaleStats = calculateStats(students.filter(_.gender == "female"), courses)printStats("女生成绩统计：", femaleStats)}
}// 测试主程序
object Test {def main(args: Array[String]): Unit = {println("=== 学生成绩统计分析 ===\n")// 测试样例1println("测试样例1：")val data1 ="""Id  gender  Math    English   Physics|301610    male   80      64        78|301611  female   65      87        58|301612  female   44      71        77|301613  female   66      71        91|301614  female   70      71       100|301615    male   72      77        72|301616  female   73      81        75|301617  female   69      77        75|301618    male   73      61        65|301619    male   74      69        68|301620    male   76      62        76|301621    male   73      69        91|301622    male   55      69        61|301623    male   50      58        75|301624  female   63      83        93|301625    male   72      54       100|301626    male   76      66        73|301627    male   82      87        79|301628  female   62      80        54|301629    male   89      77        72""".stripMarginGradeStatistics.analyze(data1)println("=" * 60)// 测试样例2println("测试样例2：")val data2 ="""Id  gender  Math    English   Physics  Science|301610    male   72   39     74   93|301611    male   75   85     93   26|301612  female   85   79     91   57|301613  female   63   89     61   62|301614    male   72   63     58   64|301615    male   99   82     70   31|301616  female  100   81     63   72|301617    male   74  100     81   59|301618  female   68   72     63  100|301619    male   63   39     59   87|301620  female   84   88     48   48|301621    male   71   88     92   46|301622    male   82   49     66   78|301623    male   63   80     83   88|301624  female   86   80     56   69|301625    male   76   69     86   49|301626    male   91   59     93   51|301627  female   92   76     79  100|301628    male   79   89     78   57|301629    male   85   74     78   80""".stripMarginGradeStatistics.analyze(data2)}
}