Scala编程初级实践

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。

• 样例一

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

• 结果
  
• 样例二

 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

• 结果
  

• 代码如下

import scala.collection.mutable.ArrayBuffer
object Student_core {

  //把所有的成绩都放在数组里   分为三个数组 array1  不分男女  array2 male  .... 筛选数据
  def get_alldata(array1:ArrayBuffer[Int],array2:ArrayBuffer[Int],array3:ArrayBuffer[Int]){
        for(i <- 2 to courseNames.length+1){
              for (j<- 0 to allStudents.length-1){
                array1.append(allStudents(j)(i).toInt)
              }
        }
        for(i <- 2 to courseNames.length+1){
              for (j<- 0 to allStudents.length-1){
                    if(allStudents(j)(1)=="male"){
                      array2.append(allStudents(j)(i).toInt)
                    }
              }
        }
        for(i <- 2 to courseNames.length+1){
              for (j<- 0 to allStudents.length-1){
                    if(allStudents(j)(1)=="female"){
                      array3.append(allStudents(j)(i).toInt)
                    }
              }
        }
  }

  def get_data(array:ArrayBuffer[Int],data:ArrayBuffer[Double],data2:ArrayBuffer[Double],Nn:Int){
        while (!array.isEmpty){
              for (i <-0 to Nn.toInt-1){   //用data来存储每个学科的成绩   存取的长度刚好是每一个学科的所有成绩
                    data.append(array(i))
              }
              array.trimStart(Nn)    //删除array里已经保存过的每学科成绩
              data2.append((data.sum/data.length).formatted("%.2f").toDouble)
              data2.append(data.min.formatted("%.2f").toDouble)
              data2.append(data.max.formatted("%.2f").toDouble)
              data.trimEnd(Nn)    //清空data
        }
  }

  def print_data(data:ArrayBuffer[Double]){
        for (i<-0 to courseNames.length-1){
              print(courseNames(i)+":  ")
              for(j<-0 to 2){
                    print(data(j)+"  ")
              }
              println()
              data.trimStart(3)
        }
  }
/**
                      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
**/


  val File = scala.io.Source.fromFile("d:/2.txt")
  val all_Data = File.getLines().map{_.split(" ")}.toList
  val courseNames = all_Data.head.drop(2)  //拿到课程名
  courseNames(0)="Math   "
  val allStudents = all_Data.tail

  def main(args: Array[String]): Unit = {

    val array1=ArrayBuffer[Int]()  //所有成绩数据  只有成绩
    val array2=ArrayBuffer[Int]()   //male的所有成绩
    val array3=ArrayBuffer[Int]()

    get_alldata(array1,array2, array3)


    val data=ArrayBuffer[Double]()
    val data2=ArrayBuffer[Double]()//data2是保存所有平均值，最小值，最大值的数组
    val Nn=(array1.length/courseNames.length)//Nn是一列数据的长度   不分男女 就是 60/3=20 male 就是42/3=13   female就是7

    val male_data2=ArrayBuffer[Double]()
    val male_Nn=array2.length/courseNames.length

    val  female_data2=ArrayBuffer[Double]()
    val  female_Nn=array3.length/courseNames.length


    get_data(array1,data,data2, Nn)
    get_data(array2,data,male_data2,male_Nn)
    get_data(array3,data,female_data2,female_Nn)


    println("course  "+"average  "+"min  "+"max  ")
    print_data(data2)
    println("course  "+"average  "+"min  "+"max(male)  ")
    print_data(male_data2)
    println("course  "+"average  "+"min  "+"max(female)  ")
    print_data(female_data2)


  }


}

运行结果输出如下