2020寒假学习01 Scala 编程初级实践
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1. 计算级数
请用脚本的方式编程计算并输出下列级数的前 n 项之和 Sn，直到 Sn 刚好大于或等于 q为止，其中 q 为大于 0 的整数，其值通过键盘输入。
Sn = 2/1+3/2+4/3+......+n+1/n
例如，若 q 的值为 50.0，则输出应为：Sn=50.416695。请将源文件保存为exercise2-1.scala，在REPL模式下测试运行，测试样例：q=1时，Sn=2；q=30时，Sn=30.891459；q=50 时，Sn=50.416695。
object test1 {
def main(args: Array[String]): Unit = {
import scala.io.StdIn
print("请输入Q值(>0)：");
var Q = StdIn.readInt();
var Sn:Double = 0;
var i:Double = 1;
while(Sn<Q){
var Sn1 = (i+1)/i;
Sn = Sn+Sn1;
i=i+1;
}
print(Sn+">"+Q);
}
}
运行结果如下：
2， 模拟图形绘制
对于一个图形绘制程序，用下面的层次对各种实体进行抽象。定义一个 Drawable 的特质，其包括一个 draw 方法，默认实现为输出对象的字符串表示。定义一个 Point 类表示点，其混入了 Drawable 特质，并包含一个 shift 方法，用于移动点。所有图形实体的抽象类为Shape，其构造函数包括一个 Point 类型，表示图形的具体位置（具体意义对不同的具体图形不一样）。Shape 类有一个具体方法 moveTo 和一个抽象方法 zoom，其中 moveTo 将图形从当前位置移动到新的位置， 各种具体图形的 moveTo 可能会有不一样的地方。zoom 方法实现对图形的放缩，接受一个浮点型的放缩倍数参数，不同具体图形放缩实现不一样。继承Shape 类的具体图形类型包括直线类 Line 和圆类 Circle。Line 类的第一个参数表示其位置，第二个参数表示另一个端点，Line 放缩的时候，其中点位置不变，长度按倍数放缩（注意，缩放时，其两个端点信息也改变了），另外，Line 的 move 行为影响了另一个端点，需要对move 方法进行重载。Circle 类第一个参数表示其圆心，也是其位置，另一个参数表示其半径，Circle 缩放的时候，位置参数不变，半径按倍数缩放。另外直线类 Line 和圆类 Circle都混入了 Drawable 特质，要求对 draw 进行重载实现，其中类 Line 的 draw 输出的信息样式为“Line:第一个端点的坐标--第二个端点的坐标)”，类 Circle 的 draw 输出的信息样式为“Circle center:圆心坐标,R=半径”。如下的代码已经给出了 Drawable 和 Point 的定义，同时也给出了程序入口 main 函数的实现，请完成 Shape 类、Line 类和 Circle 类的定义。
object test2 {
def main(args: Array[String]) {
val p=new Point(10,30)
p.draw;
val line1 = new Line(Point(0,0),Point(20,20))
line1.draw
line1.moveTo(Point(5,5)) //移动到一个新的点
line1.draw
line1.zoom(2) //放大两倍
line1.draw
val cir= new Circle(Point(10,10),5)
cir.draw
cir.moveTo(Point(30,20))
cir.draw
cir.zoom(0.5)
cir.draw
}
}
abstract class shape extends Drawable {
def moveTo(point: Point)
def zoom(position: Double)
def draw()
}
case class Point(var x:Double,var y:Double) extends Drawable{
var Px :Double=x
var Py :Double=y
def shift(deltaX:Double,deltaY:Double){
Px+=deltaX;Py+=deltaY
}
override def draw():Unit = {
println("Point:("+Px+","+Py+")")
}
}
trait Drawable{
def draw(){println(this.toString)}
}
class Line(point1: Point, point2: Point)extends shape {
override def moveTo(point: Point):Unit = {
point1.shift(point.Px,point.Py)
point2.shift(point.Px,point.Py)
}
override def zoom(position:Double): Unit ={
var lengthx = point2.Px-point1.Px
var lengthy = point2.Py-point1.Py
if(lengthx<0){
lengthx = -lengthx;
}
if(lengthy<0){
lengthy = -lengthy;
}
var newx = (lengthx/2)*(position-1);
point1.Px = point1.Px-newx;
point2.Px = point2.Px+newx;
var newy =(lengthy/2)*(position-1);
point1.Py = point1.Py-newy;
point2.Py = point2.Py+newy;
}
override def draw(): Unit = {
println("Line:(" + point1.Px + "," + point1.Py + ")--(" + point2.Px + "," + point2.Py + ")")
}
}
class Circle(point: Point, r: Double) extends shape {
var R = r
override def moveTo(point: Point): Unit = {
this.point.Px = point.Px
this.point.Py = point.Py
}
override def zoom(step: Double): Unit = {
R = R * step
}
override def draw(): Unit = {
println("Circle center:(" + point.Px + "," + point.Py + "),R=" + R);
}
}
运行结果：
3， 统计学生成绩学生的成绩清单格式如下所示，第一行为表头，各字段意思分别为学号、性别、课程名1、课程名 2 等，后面每一行代表一个学生的信息，各字段之间用空白符隔开
Id gender Math English Physics
301610 male 80 64 78
301611 female 65 87 58
...
给定任何一个如上格式的清单（不同清单里课程数量可能不一样），要求尽可能采用函数式编程，统计出各门课程的平均成绩，最低成绩，和最高成绩；另外还需按男女同学分开，
分别统计各门课程的平均成绩，最低成绩，和最高成绩。测试样例 1 如下：
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
样例 1 的统计结果输出为：
course average min max
Math: 69.20 44.00 89.00
English: 71.70 54.00 87.00
Physics: 76.65 54.00 100.00
course average min max (males)
Math: 72.67 50.00 89.00
English: 67.75 54.00 87.00
Physics: 75.83 61.00 100.00
course average min max (females)
Math: 64.00 44.00 73.00
English: 77.63 71.00 87.00
Physics: 77.88 54.00 100.00
import scala.collection.mutable.ArrayBuffer
object test3 {
def main(args: Array[String]): Unit = {
var students:ArrayBuffer[Student] = new ArrayBuffer[Student]()
students.append(new Student(301610, "male", 80, 64, 78))
students.append(new Student(301611, "female", 65, 87, 58))
students.append(new Student(301612, "female", 44, 71, 77))
students.append(new Student(301613, "female", 66, 71, 91))
students.append(new Student(301614, "female", 70, 71, 100))
students.append(new Student(301615, "male", 72, 77, 72))
students.append(new Student(301616, "female", 73, 81, 75))
students.append(new Student(301617, "female", 69, 77, 75))
students.append(new Student(301618, "male", 73, 61, 65))
students.append(new Student(301619, "male", 74, 69, 68))
students.append(new Student(301620, "male", 76, 62, 76))
students.append(new Student(301621, "male", 73, 69, 91))
students.append(new Student(301622, "male", 55, 69, 61))
students.append(new Student(301623, "male", 50, 58, 75))
students.append(new Student(301624, "female", 63, 83, 93))
students.append(new Student(301625, "male", 72, 54, 100))
students.append(new Student(301626, "male", 76, 66, 73))
students.append(new Student(301627, "male", 82, 87, 79))
students.append(new Student(301628, "female", 62, 80, 54))
students.append(new Student(301629, "male", 89, 77, 72))
println(students.length)
println(students(1).toString)
getData(students)
getDataMale(students)
getDataFeMale(students)
}
def getData(value: ArrayBuffer[Student]): Unit ={
var Mathaverage:Double=0;
var MathSum:Double = 0;
var MathMin:Double = value(0).Math;
var MathMax:Double = 0;
var Englishaverage:Double=0;
var EnglishSum:Double = 0;
var EnglishMin:Double = value(0).English;
var EnglishMax:Double = 0;
var Physicsaverage:Double=0;
var PhysicsSum:Double = 0;
var PhysicsMin:Double = value(0).Physics;
var PhysicsMax:Double = 0;
var number = value.length;
for (i <- 0 until value.length){
//三科总数
MathSum = value(i).Math+MathSum
EnglishSum = value(i).English+EnglishSum
PhysicsSum = value(i).Physics+PhysicsSum
//最大和最小
if(value(i).Math>MathMax){
MathMax=value(i).Math;
}
if(value(i).English>EnglishMax){
EnglishMax=value(i).English;
}
if(value(i).Physics>PhysicsMax){
PhysicsMax=value(i).Physics;
}
if(value(i).Math<MathMin){
MathMin=value(i).Math;
}
if(value(i).English<EnglishMin){
EnglishMin=value(i).English;
}
if(value(i).Physics<PhysicsMin){
PhysicsMin=value(i).Physics;
}
}
//平均值
Mathaverage=MathSum/number
Englishaverage=EnglishSum/number
Physicsaverage=PhysicsSum/number
println("course average min max ")
println("Math: "+Mathaverage+" "+MathMin+" "+MathMax)
println("English: "+Englishaverage+" "+EnglishMin+" "+EnglishMax)
println("Physics: "+Physicsaverage+" "+PhysicsMin+" "+PhysicsMax)
}
def getDataMale(value: ArrayBuffer[Student]): Unit = {
var Mathaverage: Double = 0;
var MathSum: Double = 0;
var MathMin: Double = value(0).Math;
var MathMax: Double = 0;
var Englishaverage: Double = 0;
var EnglishSum: Double = 0;
var EnglishMin: Double = value(0).English;
var EnglishMax: Double = 0;
var Physicsaverage: Double = 0;
var PhysicsSum: Double = 0;
var PhysicsMin: Double = value(0).Physics;
var PhysicsMax: Double = 0;
var number = 0;
for (i <- 0 until value.length) {
if (value(i).gender.equals("male")) {
number = number + 1
//三科总数
MathSum = value(i).Math + MathSum
EnglishSum = value(i).English + EnglishSum
PhysicsSum = value(i).Physics + PhysicsSum
//最大和最小
if (value(i).Math > MathMax) {
MathMax = value(i).Math;
}
if (value(i).English > EnglishMax) {
EnglishMax = value(i).English;
}
if (value(i).Physics > PhysicsMax) {
PhysicsMax = value(i).Physics;
}
if (value(i).Math < MathMin) {
MathMin = value(i).Math;
}
if (value(i).English < EnglishMin) {
EnglishMin = value(i).English;
}
if (value(i).Physics < PhysicsMin) {
PhysicsMin = value(i).Physics;
}
}
}
//平均值
Mathaverage=MathSum/number
Englishaverage=EnglishSum/number
Physicsaverage=PhysicsSum/number
println("course average min max (Male)")
Mathaverage=Mathaverage.toInt
Englishaverage=Englishaverage.toInt
Physicsaverage=Physicsaverage.toInt
println("Math: "+Mathaverage+" "+MathMin+" "+MathMax)
println("English: "+Englishaverage+" "+EnglishMin+" "+EnglishMax)
println("Physics: "+Physicsaverage+" "+PhysicsMin+" "+PhysicsMax)
}
def getDataFeMale(value: ArrayBuffer[Student]): Unit ={
var Mathaverage:Double=0;
var MathSum:Double = 0;
var MathMin:Double = value(1).Math;
var MathMax:Double = 0;
var Englishaverage:Double=0;
var EnglishSum:Double = 0;
var EnglishMin:Double = value(1).English;
var EnglishMax:Double = 0;
var Physicsaverage:Double=0;
var PhysicsSum:Double = 0;
var PhysicsMin:Double = value(1).Physics;
var PhysicsMax:Double = 0;
var number = 0;
for (i <- 0 until value.length){
if(value(i).gender.equals("female")){
number=number+1
//三科总数
MathSum = value(i).Math+MathSum
EnglishSum = value(i).English+EnglishSum
PhysicsSum = value(i).Physics+PhysicsSum
//最大和最小
if(value(i).Math>MathMax){
MathMax=value(i).Math;
}
if(value(i).English>EnglishMax){
EnglishMax=value(i).English;
}
if(value(i).Physics>PhysicsMax){
PhysicsMax=value(i).Physics;
}
if(value(i).Math<MathMin){
MathMin=value(i).Math;
}
if(value(i).English<EnglishMin){
EnglishMin=value(i).English;
}
if(value(i).Physics<PhysicsMin){
PhysicsMin=value(i).Physics;
}
}
}
//平均值
Mathaverage=MathSum/number
Englishaverage=EnglishSum/number
Physicsaverage=PhysicsSum/number
println("course average min max (FeMale)")
Mathaverage=Mathaverage.toInt
Englishaverage=Englishaverage.toInt
Physicsaverage=Physicsaverage.toInt
println("Math: "+Mathaverage+" "+MathMin+" "+MathMax)
println("English: "+Englishaverage+" "+EnglishMin+" "+EnglishMax)
println("Physics: "+Physicsaverage+" "+PhysicsMin+" "+PhysicsMax)
}
}
class Student(id1:Int,gender1:String,Math1:Double,English1:Double,Physics1:Double){
var id:Int = id1
var gender:String = gender1
var Math:Double = Math1
var English:Double = English1
var Physics:Double = Physics1
override def toString = s"Student($id, $gender, $Math, $English, $Physics)"
}
运行结果如下：
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