StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
4536937
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2010-12-27T06:21:44.783
FavoriteCount
0
LastActivityDate
2010-12-27T06:21:44.783
LastEditDate
LastEditorUserId
0
OwnerUserId
257449
ParentId
4534230
PostTypeId
2
Score
2
ViewCount
0
LastEditorDisplayName
text
Body
Not really answering the question but since I spent some times benchmarking various combinations... You can get better performance if you use <code>Iterator</code>, <code>ArrayBuffer</code> and avoid <code>takeWhile</code> in the inner loop, to minimize memory allocations. <pre><code>def primes2(): Stream[Int] = { def sieve(p: Int, ps: ArrayBuffer[Int]): Stream[Int] = { def hasNoDivisor(prime_? :Int, j: Int = 0): Boolean = { val n = ps(j) if (n*n > prime_?) true else if (prime_? % n == 0) false else hasNoDivisor(prime_?, j+1) } p #:: { val nextprime = Iterator.from(ps.last + 2, 2).find(hasNoDivisor(_)).get sieve(nextprime, ps += nextprime) } } sieve(3, ArrayBuffer(3)) } </code></pre> Here is a version with <code>Iterator</code> instead of <code>Stream</code>, it's faster and you can always use <code>primes3().toStream</code> to get a Stream if needed. <pre><code>def primes3() = List(2,3).iterator ++ new Iterator[Int] { val ps = ArrayBuffer[Int](3) def hasNoDivisor(prime_? :Int, j: Int = 0): Boolean = { val n = ps(j) if (n*n > prime_?) true else if (prime_? % n == 0) false else hasNoDivisor(prime_?, j+1) } def hasNext = true def next() = { val nextprime = Iterator.from(ps.last + 2, 2).find(hasNoDivisor(_)).get ps += nextprime nextprime } } </code></pre> Results: <pre><code>primes : warming... primes : running... primes : elapsed: 3.711 res39: Int = 283145 primes2: warming... primes2: running... primes2: elapsed: 1.039 res40: Int = 283145 primes3: warming... primes3: running... primes3: elapsed: 0.530 res41: Int = 283146 </code></pre> I also tried replacing <code>from</code>, <code>find</code> and <code>hasNoDivisor</code> with a couple of <code>while</code> loops, and that was faster, but less comprehensible.
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POWhy Stream/lazy val implementation using is faster than ListBuffer one
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. This table or related slice is empty.
UserOwnerUserId
1. UShuynhjl
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
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
CommentsPostId
1. This table or related slice is empty.

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.