scala - 如何使用 Scala 组合字符串中的值？

Question

我想将值组合成一个字符串。例如，

Let A = a,b,c,d

我想要这样的组合，

AComb = a,b,c,d,ab,ac,ad,bc,bd,cd,abc,abd,bcd,acd

Answer 1

我假设 A 是一个 Set

scala> val A =Set("a","b","c","d")
A: scala.collection.immutable.Set[String] = Set(a, b, c, d)


scala> val AComb=A.toSet[String].subsets.map(_.mkString).toVector
AComb: Vector[String] = Vector("", a, b, c, d, ab, ac, ad, bc, bd, cd, abc, abd, acd, bcd, abcd)

我认为您不需要第一个元素，所以您可以尝试

scala> val AComb=A.toSet[String].subsets.map(_.mkString).toVector.tail
AComb: scala.collection.immutable.Vector[String] = Vector(a, b, c, d, ab, ac, ad, bc, bd, cd, abc, abd, acd, bcd, abcd)

删除第一个和最后一个元素

scala> val AComb=A.toSet[String].subsets.map(_.mkString).toVector.init.tail
AComb: scala.collection.immutable.Vector[String] = Vector(a, b, c, d, ab, ac, ad, bc, bd, cd, abc, abd, acd, bcd)

根据评论更新

scala> val xc1=Set("sunny","hot","high","FALSE","no")
xc1: scala.collection.immutable.Set[String] = Set(sunny, FALSE, hot, no, high)

scala> val AComb=xc1.toSet[String].subsets.map(_.mkString(" ")).toVector.tail;
AComb: scala.collection.immutable.Vector[String] = Vector(sunny, FALSE, hot, no, high, sunny FALSE, sunny hot, sunny no, sunny high, FALSE hot, FALSE no, FALSE high, hot no, hot high, no high, sunny FALSE hot, sunny FALSE no, sunny FALSE high, sunny hot no, sunny hot high, sunny no high, FALSE hot no, FALSE hot high, FALSE no high, hot no high, sunny FALSE hot no, sunny FALSE hot high, sunny FALSE no high, sunny hot no high, FALSE hot no high)