Question

我正在尝试从地图中选择最后一个元素，并将其与地图中的其他最后元素进行比较，以确定所选元素是高还是低。

到目前为止，我可以从用户输入中选择元素，但无法解决如何遍历地图并将其与其他元素进行比较：

def menu(f: (String) => (String, Int)) = {
print("Number > ")
val data = f(readLine)
println(s"${data._1}: ${data._2}")

}

以下是元素来自的地图：

val mapdata = Map(
  "A1" -> List(9, 7, 2, 0, 0, 2, 7, 9, 1, 2, 4, 1, 9, 6, 5, 3, 2, 3, 7, 2, 8, 5, 4, 5, 1, 6, 5, 2, 4, 1),
  "B2" -> List(0, 7, 6, 3, 3, 3, 1, 2, 9, 2, 9, 7, 4, 7, 3, 6, 3, 9, 5, 2, 9, 7, 3, 4, 6, 3, 4, 3, 4, 1),
  "C3" -> List(8, 7, 1, 8, 0, 5, 8, 0, 5, 9, 7, 5, 3, 7, 9, 8, 1, 4, 6, 5, 6, 6, 3, 6, 8, 8, 7, 4, 0, 6),
  "D4" -> List(2, 9, 5, 7, 3, 8, 6, 9, 7, 9, 0, 1, 3, 1, 3, 0, 0, 1, 3, 8, 5, 4, 0, 9, 7, 1, 4, 5, 2, 9),
  "E5" -> List(2, 6, 8, 0, 3, 5, 2, 1, 5, 9, 4, 5, 3, 5, 5, 8, 8, 2, 5, 9, 3, 8, 6, 7, 8, 7, 4, 1, 2, 3),
  "F6" -> List(2, 7, 5, 9, 1, 9, 2, 4, 1, 6, 3, 7, 4, 3, 4, 5, 9, 2, 2, 4, 8, 7, 9, 2, 2, 7, 9, 1, 6, 9),
  "G7" -> List(6, 9, 5, 0, 8, 0, 0, 5, 8, 5, 8, 7, 1, 6, 6, 1, 5, 2, 2, 7, 9, 5, 5, 9, 1, 4, 4, 0, 2, 0),
  "H8" -> List(2, 8, 8, 3, 2, 1, 1, 8, 5, 9, 0, 2, 1, 6, 9, 7, 9, 6, 7, 7, 0, 9, 5, 2, 5, 0, 2, 1, 8, 6),
  "I9" -> List(2, 1, 8, 2, 4, 4, 2, 4, 9, 4, 0, 6, 9, 5, 9, 4, 9, 1, 8, 6, 3, 4, 4, 3, 7, 9, 1, 2, 6, 6)
)

例如我选择H8，其最后一个元素是6

然后我想将它与所有最后一个元素进行比较，并说它是否高于或低于最后一个元素。

提前致谢

Answer 1

我不确定我是否理解正确。您可以通过调用last来访问列表的最后一个元素。

object A extends App {
  val mapdata: Map[String, List[Int]] = Map(
  "A1" -> List(9, 7, 2, 0, 0, 2, 7, 9, 1, 2, 4, 1, 9, 6, 5, 3, 2, 3, 7, 2, 8, 5, 4, 5, 1, 6, 5, 2, 4, 1),
  "B2" -> List(0, 7, 6, 3, 3, 3, 1, 2, 9, 2, 9, 7, 4, 7, 3, 6, 3, 9, 5, 2, 9, 7, 3, 4, 6, 3, 4, 3, 4, 1),
  "C3" -> List(8, 7, 1, 8, 0, 5, 8, 0, 5, 9, 7, 5, 3, 7, 9, 8, 1, 4, 6, 5, 6, 6, 3, 6, 8, 8, 7, 4, 0, 6),
  "D4" -> List(2, 9, 5, 7, 3, 8, 6, 9, 7, 9, 0, 1, 3, 1, 3, 0, 0, 1, 3, 8, 5, 4, 0, 9, 7, 1, 4, 5, 2, 9),
  "E5" -> List(2, 6, 8, 0, 3, 5, 2, 1, 5, 9, 4, 5, 3, 5, 5, 8, 8, 2, 5, 9, 3, 8, 6, 7, 8, 7, 4, 1, 2, 3),
  "F6" -> List(2, 7, 5, 9, 1, 9, 2, 4, 1, 6, 3, 7, 4, 3, 4, 5, 9, 2, 2, 4, 8, 7, 9, 2, 2, 7, 9, 1, 6, 9),
  "G7" -> List(6, 9, 5, 0, 8, 0, 0, 5, 8, 5, 8, 7, 1, 6, 6, 1, 5, 2, 2, 7, 9, 5, 5, 9, 1, 4, 4, 0, 2, 0),
  "H8" -> List(2, 8, 8, 3, 2, 1, 1, 8, 5, 9, 0, 2, 1, 6, 9, 7, 9, 6, 7, 7, 0, 9, 5, 2, 5, 0, 2, 1, 8, 6),
  "I9" -> List(2, 1, 8, 2, 4, 4, 2, 4, 9, 4, 0, 6, 9, 5, 9, 4, 9, 1, 8, 6, 3, 4, 4, 3, 7, 9, 1, 2, 6, 6)
  )

  val choice = "H8"
  val numberToBeCompared = mapdata.getOrElse(choice, throw new RuntimeException(s"couldn't find $choice")).last
  mapdata.filter(_._1 != choice)
    .values
    .foreach(list => {
      if (list.last > numberToBeCompared)
        println(s"${list.last} > $numberToBeCompared")
      else
        println(s"${list.last} <= $numberToBeCompared")
    })
}

结果：

1 <= 6
1 <= 6
0 <= 6
3 <= 6
9 > 6
9 > 6
6 <= 6
6 <= 6

这是你需要的吗？

请注意，我仍然学习Scala，因此可能有更好的方法。我也不知道mapdata中的任何列表是否都可以为空，因此如有必要，请使用Option。

//编辑如果你想要这些字母，你可以尝试这样：

val choice = "H8"
val numberToBeCompared = mapdata.getOrElse(choice, throw new RuntimeException(s"couldn't find $choice")).last
mapdata.filter(_._1 != choice)
  .foreach(entry => {
    if (entry._2.last > numberToBeCompared)
      println(s"${choice} > ${entry._1}")
    else
      println(s"${choice} <= ${entry._1}")
    })

H8 <= A1
H8 <= B2
H8 <= G7
H8 <= E5
H8 > D4
H8 > F6
H8 <= C3
H8 <= I9

你需要记住，当你遍历mapdata时，你会得到一个条目。 entry._1是键（你的字符串），entry._2是列表。

将地图中的元素与地图的其余部分进行比较

1 个答案: