如何将第一个列表中的每个元素添加到Scala中相应的列表中？

因此，我有一份清单：

    var data = List(
      List(Some(313.062468), Some(27.847252), Some(29.847252)),
      List(Some(301.873641), Some(42.884065), Some(89.847252)),
      List(Some(332.373186), Some(53.509768), Some(10.847252))
    )

如何计算基本函数，如： 对于每个列表的每个元素：

第一排 第二列 第三纵队 我现在被困在这里 这仅打印每个嵌套列表的标题。我不知道如何获取嵌套元素的每个元素并进行上述计算

结果应该是这样的：

List(
  List(Some(-0.03573991820699504), Some(0.5399747522663995), Some(88.847252) )
  List(Some(0.10103414428290529), Some(0.24777742035415723), Some(9.847252) )
)

---

您可能希望从使用

transpose

方法开始，并从那里处理所需的逻辑。下面是对示例数据调用

transpose

的结果：

scala> data.transpose.foreach(println)
List(Some(313.062468), Some(301.873641), Some(332.373186))
List(Some(27.847252), Some(42.884065), Some(53.509768))
List(Some(29.847252), Some(89.847252), Some(10.847252))

---

转置、展平和压缩

val list = data.transpose.flatMap(_.flatten)
list.tail zip list map { case (a, b) => (b - a)/b }

scala> val list = data.transpose.flatMap(_.flatten)
list: List[Double] = List(313.062468, 301.873641, 332.373186, 27.847252, 42.884065, 53.509768, 29.847252, 89.847252, 10.847252)

Scala REPL

scala> list.tail zip list map { case (a, b) => (b - a)/b }
res19: List[Double] = List(0.03573991820699504, -0.10103414428290529, 0.9162169116734945, -0.5399747522663995, -0.24777742035415723, 0.4422092803691468, -2.010235314125401, 0.8792700749489812)

scala> var data = List(
     |       List(Some(313.062468), Some(27.847252), Some(29.847252)),
     |       List(Some(301.873641), Some(42.884065), Some(89.847252)),
     |       List(Some(332.373186), Some(53.509768), Some(10.847252))
     |     )
data: List[List[Some[Double]]] = List(List(Some(313.062468), Some(27.847252), Some(29.847252)), List(Some(301.873641), Some(42.884065), Some(89.847252)), List(Some(332.373186), Some(53.509768), Some(10.847252)))

scala> data.zip(data.tail)
res0: List[(List[Some[Double]], List[Some[Double]])] = List((List(Some(313.062468), Some(27.847252), Some(29.847252)),List(Some(301.873641), Some(42.884065), Some(89.847252))), (List(Some(301.873641), Some(42.884065), Some(89.847252)),List(Some(332.373186), Some(53.509768), Some(10.847252))))

scala> data.zip(data.tail).map { case (alist, blist) => alist zip blist }
res1: List[List[(Some[Double], Some[Double])]] = List(List((Some(313.062468),Some(301.873641)), (Some(27.847252),Some(42.884065)), (Some(29.847252),Some(89.847252))), List((Some(301.873641),Some(332.373186)), (Some(42.884065),Some(53.509768)), (Some(89.847252),Some(10.847252))))

scala> data.zip(data.tail).map { case (alist, blist) => alist zip blist }.flatten
res2: List[(Some[Double], Some[Double])] = List((Some(313.062468),Some(301.873641)), (Some(27.847252),Some(42.884065)), (Some(29.847252),Some(89.847252)), (Some(301.873641),Some(332.373186)), (Some(42.884065),Some(53.509768)), (Some(89.847252),Some(10.847252)))

scala> data.zip(data.tail).map { case (alist, blist) => alist zip blist }.flatten
res3: List[(Some[Double], Some[Double])] = List((Some(313.062468),Some(301.873641)), (Some(27.847252),Some(42.884065)), (Some(29.847252),Some(89.847252)), (Some(301.873641),Some(332.373186)), (Some(42.884065),Some(53.509768)), (Some(89.847252),Some(10.847252)))

scala> data.zip(data.tail).map { case (alist, blist) => alist.flatten zip blist.flatten }.flatten
res4: List[(Double, Double)] = List((313.062468,301.873641), (27.847252,42.884065), (29.847252,89.847252), (301.873641,332.373186), (42.884065,53.509768), (89.847252,10.847252))

scala> data.zip(data.tail).map { case (alist, blist) => alist.flatten zip blist.flatten }.flatten.map { case (a, b) => (b - a)/b}
res5: List[Double] = List(-0.037064604126863805, 0.35063870460974256, 0.6678000569232768, 0.09176295286347183, 0.19857501531309202, -7.282950557431505)

不是一个简洁的解决方案，但很有效

data.zip(data.tail).map { case (alist, blist) => alist.flatten zip blist.flatten }.flatten.map { case (a, b) => (b - a)/b}

重要的代码行

scala> data.zip(data.tail).map { case (alist, blist) => alist.flatten zip blist.flatten }.flatten
res4: List[(Double, Double)] = List((313.062468,301.873641), (27.847252,42.884065), (29.847252,89.847252), (301.873641,332.373186), (42.884065,53.509768), (89.847252,10.847252))

scala> data.zip(data.tail).map { case (alist, blist) => alist.flatten zip blist.flatten }.flatten.map { case (a, b) => (b - a)/b}
res5: List[Double] = List(-0.037064604126863805, 0.35063870460974256, 0.6678000569232768, 0.09176295286347183, 0.19857501531309202, -7.282950557431505)

Scala REPL

scala> list.tail zip list map { case (a, b) => (b - a)/b }
res19: List[Double] = List(0.03573991820699504, -0.10103414428290529, 0.9162169116734945, -0.5399747522663995, -0.24777742035415723, 0.4422092803691468, -2.010235314125401, 0.8792700749489812)

scala> var data = List(
     |       List(Some(313.062468), Some(27.847252), Some(29.847252)),
     |       List(Some(301.873641), Some(42.884065), Some(89.847252)),
     |       List(Some(332.373186), Some(53.509768), Some(10.847252))
     |     )
data: List[List[Some[Double]]] = List(List(Some(313.062468), Some(27.847252), Some(29.847252)), List(Some(301.873641), Some(42.884065), Some(89.847252)), List(Some(332.373186), Some(53.509768), Some(10.847252)))

scala> data.zip(data.tail)
res0: List[(List[Some[Double]], List[Some[Double]])] = List((List(Some(313.062468), Some(27.847252), Some(29.847252)),List(Some(301.873641), Some(42.884065), Some(89.847252))), (List(Some(301.873641), Some(42.884065), Some(89.847252)),List(Some(332.373186), Some(53.509768), Some(10.847252))))

scala> data.zip(data.tail).map { case (alist, blist) => alist zip blist }
res1: List[List[(Some[Double], Some[Double])]] = List(List((Some(313.062468),Some(301.873641)), (Some(27.847252),Some(42.884065)), (Some(29.847252),Some(89.847252))), List((Some(301.873641),Some(332.373186)), (Some(42.884065),Some(53.509768)), (Some(89.847252),Some(10.847252))))

scala> data.zip(data.tail).map { case (alist, blist) => alist zip blist }.flatten
res2: List[(Some[Double], Some[Double])] = List((Some(313.062468),Some(301.873641)), (Some(27.847252),Some(42.884065)), (Some(29.847252),Some(89.847252)), (Some(301.873641),Some(332.373186)), (Some(42.884065),Some(53.509768)), (Some(89.847252),Some(10.847252)))

scala> data.zip(data.tail).map { case (alist, blist) => alist zip blist }.flatten
res3: List[(Some[Double], Some[Double])] = List((Some(313.062468),Some(301.873641)), (Some(27.847252),Some(42.884065)), (Some(29.847252),Some(89.847252)), (Some(301.873641),Some(332.373186)), (Some(42.884065),Some(53.509768)), (Some(89.847252),Some(10.847252)))

scala> data.zip(data.tail).map { case (alist, blist) => alist.flatten zip blist.flatten }.flatten
res4: List[(Double, Double)] = List((313.062468,301.873641), (27.847252,42.884065), (29.847252,89.847252), (301.873641,332.373186), (42.884065,53.509768), (89.847252,10.847252))

scala> data.zip(data.tail).map { case (alist, blist) => alist.flatten zip blist.flatten }.flatten.map { case (a, b) => (b - a)/b}
res5: List[Double] = List(-0.037064604126863805, 0.35063870460974256, 0.6678000569232768, 0.09176295286347183, 0.19857501531309202, -7.282950557431505)

---

转换列表，然后使用

.slideing（2）

获得元素的滚动窗口：

scala> def diffPercent(o1: Option[Double], o2: Option[Double]) = (o1, o2) match {
         case (Some(d1), Some(d2)) => Some((d2 - d1) / d1)  // need to handle d1 == 0 too
         case _ => None
       }
diffPercent: (o1: Option[Double], o2: Option[Double])Option[Double]

// sample value before the final operation
scala> data.transpose.map(_.sliding(2).toList) // .toList to show the values in REPL
res13: List[List[List[Some[Double]]]] = List(List(List(Some(313.062468), Some(301.873641)), List(Some(301.873641), Some(332.373186))), ...)

scala> data.transpose.map(_.sliding(2).map {
         case o1 :: o2 :: Nil => diffPercent(o1, o2)
         case _ => None // source has less than 2 elems
       }.toList).transpose  // transpose back the list
res17: List[List[Option[Double]]] = List(List(Some(-0.03573991820699504), Some(0.5399747522663995), Some(2.010235314125401)), List(Some(0.10103414428290529), Some(0.24777742035415723), Some(-0.8792700749489812)))

---

这个比其他的简单一点，并且不使用

转置

。它非常接近@pamu。我从@Marth的答案中借用了

diffPercent

data.sliding(2)
    .map{case List(a, b) => (a zip b).map {case (x,y) => diffPercent(x,y)}}
    .toList

---

我明白了，那么我该如何在转置中获取每个列表的每个元素呢？但是当被展平时，列表将被合并，这是我不想要的。我要获取每个列表头的元素，然后获取每个列表中的下一个元素，依此类推。。就像柱子一样。我想从列透视图的角度来表示数据，例如，您可以执行类似于

data.transpose.map{案例列表（一些（a），一些（b），一些（c））=>/*您涉及列a、b和c的逻辑*/？}

这正是

transpose

所做的。直观地说，它将行转换为列，反之亦然。很抱歉删除了注释，我意识到这不是你想要的。我真的很喜欢你的实现方式，只是想知道，输出的顺序不正确，也许你知道为什么吗？@NaseebullahSafi:我的错，我忘了将列表调回原处。我编辑了我的回答谢谢Marth，真的很感谢你非常有价值的天赋。嘿，这里，输出的顺序似乎不对。有什么办法可以解决吗？这是你围绕这个问题提出的第三个非常基本的问题。您不应该使用SO作为编写代码的机器人。你有没有考虑过去学习一下Scala？有很多很好的教程可供选择。道歉@thearchetypaull不会再发生了。我是Scala的新手，非常感谢您的帮助。说真的，您自己解决这个问题会收获更多，当您真的陷入困境时，可以问一个具体的问题。道歉@thearchetypall谢谢。非常感谢。真的

scala> def diffPercent(o1: Option[Double], o2: Option[Double]) = (o1, o2) match {
         case (Some(d1), Some(d2)) => Some((d2 - d1) / d1)  // need to handle d1 == 0 too
         case _ => None
       }
diffPercent: (o1: Option[Double], o2: Option[Double])Option[Double]

// sample value before the final operation
scala> data.transpose.map(_.sliding(2).toList) // .toList to show the values in REPL
res13: List[List[List[Some[Double]]]] = List(List(List(Some(313.062468), Some(301.873641)), List(Some(301.873641), Some(332.373186))), ...)

scala> data.transpose.map(_.sliding(2).map {
         case o1 :: o2 :: Nil => diffPercent(o1, o2)
         case _ => None // source has less than 2 elems
       }.toList).transpose  // transpose back the list
res17: List[List[Option[Double]]] = List(List(Some(-0.03573991820699504), Some(0.5399747522663995), Some(2.010235314125401)), List(Some(0.10103414428290529), Some(0.24777742035415723), Some(-0.8792700749489812)))

data.sliding(2)
    .map{case List(a, b) => (a zip b).map {case (x,y) => diffPercent(x,y)}}
    .toList