如何对元组列表求和 [英] How to sum a list of tuples

问题描述

给定以下元组列表...

Given the following list of tuples...

val list = List((1, 2), (1, 2), (1, 2))

...我如何对所有值求和并获得这样的单个元组?

... how do I sum all the values and obtain a single tuple like this?

(3, 6)

推荐答案

使用 foldLeft 方法.请查看 scaladoc 了解更多信息.

Using the foldLeft method. Please look at the scaladoc for more information.

scala> val list = List((1, 2), (1, 2), (1, 2))
list: List[(Int, Int)] = List((1,2), (1,2), (1,2))

scala> list.foldLeft((0, 0)) { case ((accA, accB), (a, b)) => (accA + a, accB + b) }
res0: (Int, Int) = (3,6)

使用解压.不如上述解决方案有效.也许更具可读性.

Using unzip. Not as efficient as the above solution. Perhaps more readable.

scala> list.unzip match { case (l1, l2) => (l1.sum, l2.sum) }
res1: (Int, Int) = (3,6) 

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