如何将 Scala 列表成对？
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How do you turn a Scala list into pairs?
提问by Garrett Hall
I am trying to split Scala list like List(1,2,3,4)into pairs (1,2) (2,3) (3,4), what's a simple way to do this?
我正在尝试将 Scala 列表List(1,2,3,4)分成对(1,2) (2,3) (3,4)，有什么简单的方法可以做到这一点？
回答by Luigi Plinge
val xs = List(1,2,3,4)
xs zip xs.tail
// res1: List[(Int, Int)] = List((1,2), (2,3), (3,4))
As the docs say, zip
正如文档所说， zip
Returns a list formed from this list and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.
通过将相应的元素成对组合，返回由此列表和另一个可迭代集合形成的列表。如果两个集合之一比另一个长，则忽略其剩余元素。
So List('a,'b,'c,'d)zipped with List('x,'y,'z)is List(('a,'x), ('b,'y), ('c,'z))with the final 'dof the first one ignored.
所以List('a,'b,'c,'d)压缩List('x,'y,'z)是第一个List(('a,'x), ('b,'y), ('c,'z))的最后'd一个被忽略。
From your example, the tailof List(1,2,3,4)is List(2,3,4)so you can see how these zip together in pairs.
从您的示例中，tailofList(1,2,3,4)是List(2,3,4)这样您就可以看到这些是如何成对地压缩在一起的。
回答by Jakob Odersky
To produce a list of pairs (i.e. tuples) try this
要产生对（即元组）的列表，试试这个
List(1,2,3,4,5).sliding(2).collect{case List(a,b) => (a,b)}.toList
回答by Brian
List(1,2,3,4).sliding(2).map(x => (x.head, x.tail.head)).toList
res0: List[(Int, Int)] = List((1,2), (2,3), (3,4))
