list 如何从列表的元素创建所有可能的组合？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/13109720/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to create all possible combinations from the elements of a list?
提问by Shakti
I have the following list:
我有以下清单：
List(a, b, c, d, e)
How to create all possible combinations from the above list?
如何从上面的列表中创建所有可能的组合？
I expect something like:
我期待这样的事情：
a
ab
abc
回答by Kim Stebel
Or you could use the subsetsmethod. You'll have to convert your list to a set first though.
或者你可以使用该subsets方法。不过，您必须先将列表转换为一组。
scala> List(1,2,3).toSet[Int].subsets.map(_.toList).toList
res9: List[List[Int]] = List(List(), List(1), List(2), List(3), List(1, 2), List(1, 3), List(2, 3), List(1, 2, 3))
回答by pagoda_5b
def combine(in: List[Char]): Seq[String] =
for {
len <- 1 to in.length
combinations <- in combinations len
} yield combinations.mkString
回答by Science_Fiction
回答by Santosh Gokak
val xs = List( 'a', 'b' , 'c' , 'd' , 'e' )
(1 to xs.length flatMap (x => xs.combinations(x))) map ( x => x.mkString(""))
This should give you all the combination concatenated by empty String.
这应该为您提供由空字符串连接的所有组合。
