当任何元素比头元素长时 List.transpose 崩溃

发布于 2024-10-17 23:07:30 字数 550 浏览 1 评论 0原文

如图所示：

scala> List(List(1, 2), List(3, 4), List(5, 6)) transpose
res7: List[List[Int]] = List(List(1, 3, 5), List(2, 4, 6))

scala> List(List(1, 2), List(3), List(5, 6)) transpose
res8: List[List[Int]] = List(List(1, 3, 5), List(2, 6))

scala> List(List(1, 2), List(3, 4, 7), List(5, 6)) transpose
java.lang.IndexOutOfBoundsException: 2
        at scala.collection.immutable.Vector.checkRangeConvert(Vector.scala:104)
...

这种行为是故意的吗？如果是这样，为什么？

编辑：尽管问题的一部分已经得到澄清，我仍然想提出一个接受不规则尺寸的方法版本（可能使用不同的名称）。

原文

As illustrated:

scala> List(List(1, 2), List(3, 4), List(5, 6)) transpose
res7: List[List[Int]] = List(List(1, 3, 5), List(2, 4, 6))

scala> List(List(1, 2), List(3), List(5, 6)) transpose
res8: List[List[Int]] = List(List(1, 3, 5), List(2, 6))

scala> List(List(1, 2), List(3, 4, 7), List(5, 6)) transpose
java.lang.IndexOutOfBoundsException: 2
        at scala.collection.immutable.Vector.checkRangeConvert(Vector.scala:104)
...

Is this behaviour deliberate? If so, why?

EDIT: even though part of the question has been clarified, I'd still like to propose a version of this method (perhaps with a different name) that accepts irregular sizes.

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我的黑色迷你裙 2024-10-24 23:07:30

是的，这是故意的。任何使用不规则尺寸的尝试都会很快失败。查看错误报告 https://issues.scala-lang.org/browse/SI -3399。另请查看如何为您的案例编写转置：Scala 中是否有一种安全的方法来转置不等长列表的列表？

它在旧方法中工作。其中 7 被默默地忽略，而在前面的示例中，所有数字都出现在结果中。我想这是不可取的：

scala> List.transpose(List(List(1, 2), List(3, 4, 7), List(5, 6)))
warning: there were 1 deprecation warnings; re-run with -deprecation for details
res4: List[List[Int]] = List(List(1, 3, 5), List(2, 4, 6))

Yes it's intentional. It fails fast to any attempt to use irregular sizes. Check out the bug report https://issues.scala-lang.org/browse/SI-3399. Also take a look at how to write a transpose for your case: Is there a safe way in Scala to transpose a List of unequal-length Lists?

It works in the old method. Where 7 is silently ignored whereas in the previous examples all numbers appeared the result. I guess this was undesirable:

scala> List.transpose(List(List(1, 2), List(3, 4, 7), List(5, 6)))
warning: there were 1 deprecation warnings; re-run with -deprecation for details
res4: List[List[Int]] = List(List(1, 3, 5), List(2, 4, 6))

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