如何用Scala语言对多个Colmun(超过十列)进行排序。例如:
1 2 3 4
4 5 6 3
1 2 1 1
2 3 5 10
所需的输出
1 2 1 1
1 2 3 3
2 3 5 4
4 5 6 10
不多。
val input = io.Source.fromFile("junk.txt") // open file
.getLines // load all contents
.map(_.split("\W+")) // turn rows into Arrays
.map(_.map(_.toInt)) // Arrays of Ints
val output = input.toList // from Iterator to List
.transpose // swap rows/columns
.map(_.sorted) // sort rows
.transpose // swap back
output.foreach(x => println(x.mkString(" "))) // report results
注意:这允许数字之间的任何空格,但是如果它遇到其他分离器(逗号等),或者行以空格开头,它将无法创建预期的Array[Int]
。
另外,如果行的大小不一样,则transpose
将投掷。
我遵循以下算法。首先更改行和列的尺寸。然后对行进行排序,然后再次更改尺寸以带回原始的行柱配置。这是概念的示例证明。
object SO_42720909 extends App {
// generating dummy data
val unsortedData = getDummyData(2, 3)
prettyPrint(unsortedData)
println("----------------- ")
// altering the dimension
val unsortedAlteredData = alterDimension(unsortedData)
// prettyPrint(unsortedAlteredData)
// sorting the altered data
val sortedAlteredData = sort(unsortedAlteredData)
// prettyPrint(sortedAlteredData)
// bringing back original dimension
val sortedData = alterDimension(sortedAlteredData)
prettyPrint(sortedData)
def alterDimension(data: Seq[Seq[Int]]): Seq[Seq[Int]] = {
val col = data.size
val row = data.head.size // make it safe
for (i <- (0 until row))
yield for (j <- (0 until col)) yield data(j)(i)
}
def sort(data: Seq[Seq[Int]]): Seq[Seq[Int]] = {
for (row <- data) yield row.sorted
}
def getDummyData(row: Int, col: Int): Seq[Seq[Int]] = {
val r = scala.util.Random
for (i <- (1 to row))
yield for (j <- (1 to col)) yield r.nextInt(100)
}
def prettyPrint(data: Seq[Seq[Int]]): Unit = {
data.foreach(row => {
println(row.mkString(", "))
})
}
}