StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
10667788
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
1
CommunityOwnedDate
CreationDate
2012-05-19T18:22:34.877
FavoriteCount
0
LastActivityDate
2012-05-19T18:22:34.877
LastEditDate
LastEditorUserId
0
OwnerUserId
334519
ParentId
10662462
PostTypeId
2
Score
8
ViewCount
0
LastEditorDisplayName
text
Body
I'm sure the following messy version using type classes could be cleaned up a lot, but it works as a quick proof-of-concept. I don't see an easy way to get the return types right without dependent method types (I'm sure it's possible), so you'll have to use <code>-Xexperimental</code>: <pre><code>trait Mapping[A, B, C] { type M[D] <: PartialFunction[A, D] def domain(c: C): Seq[A] def fromPairs[D](ps: Seq[(A, D)]): M[D] def codomain(c: C)(implicit ev: C <:< PartialFunction[A, B]) = domain(c).map(c) def toPairs(c: C)(implicit ev: C <:< PartialFunction[A, B]) = domain(c).map(a => (a, c(a))) } implicit def seqMapping[A, B <: Seq[A]] = new Mapping[Int, A, B] { type M[C] = Seq[C] def domain(c: B) = 0 until c.size def fromPairs[C](ps: Seq[(Int, C)]) = ps.sortBy(_._1).map(_._2) } implicit def mapMapping[A, B, C <: Map[A, B]] = new Mapping[A, B, C] { type M[D] = Map[A, D] def domain(c: C) = c.keys.toSeq def fromPairs[D](ps: Seq[(A, D)]) = ps.toMap } def transpose[A, B, C, M, N](m: M)(implicit pev: M <:< PartialFunction[A, N], qev: N <:< PartialFunction[B, C], mev: Mapping[A, N, M], nev: Mapping[B, C, N] ) = nev.fromPairs(nev.domain(mev.codomain(m).head).map(b => b -> mev.fromPairs(mev.toPairs(m).map { case (a, c) => a -> c(b) }) )) </code></pre> And now for some tests: <pre><code>scala> println(transpose(List(Map("a" -> 1, "b" -> 13), Map("b" -> 99, "a" -> 14)))) Map(a -> Vector(1, 14), b -> Vector(13, 99)) scala> println(transpose(Map('a' -> List(1, 2, 3), 'z' -> List(4, 5, 6)))) Vector(Map(a -> 1, z -> 4), Map(a -> 2, z -> 5), Map(a -> 3, z -> 6)) scala> println(transpose(Map("x" -> Map(4 -> 'a, 99 -> 'z), "y" -> Map(4 -> 'b, 99 -> 's)))) Map(4 -> Map(x -> 'a, y -> 'b), 99 -> Map(x -> 'z, y -> 's)) </code></pre> So it's working as desired.
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POTransposing arbitrary collection-of-collections in Scala
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. This table or related slice is empty.
UserOwnerUserId
1. USTravis Brown
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. POTransposing arbitrary collection-of-collections in Scala
 singulars
 PostTypePostTypeId
 PTQuestion
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
2. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
3. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
CommentsPostId
1. COThanks - this is very useful ! It took me quite some time to understand what you have done because I am not familiar with some of the advanced features of Scala that you have used (it's a great excuse for me to learn these features in more detail now !).
 singulars
 PostPostId
 PO
 UserUserId
 USAshwin

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.