StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
19588807
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
8
CommunityOwnedDate
CreationDate
2013-10-25T11:38:49.050
FavoriteCount
0
LastActivityDate
2013-10-25T15:07:42.837
LastEditDate
2017-05-23T12:02:31.193
LastEditorUserId
-1
OwnerUserId
1281433
ParentId
19587520
PostTypeId
2
Score
7
ViewCount
0
LastEditorDisplayName
text
Body
You count the number of edges in a unique path using SPARQL's property paths and aggregate functions. For instance, with data like this, which contains two paths that we care about (a to c with two edges, and d to g with three edges): <pre><code>@prefix : <https://stackoverflow.com/questions/19587520/sparql-path-between-two-instance/> . :a :p :b . # a to c is a path of length 2 :b :p :c . :d :p :e . # d to g is a path of length 3 :e :p :f . :f :p :g . </code></pre> you can use a query like the following one. Notice that I've used the specific property <code>:p</code>, rather than a variable. This is necessary, because <a href="http://www.w3.org/TR/sparql11-query/#pp-language" rel="nofollow noreferrer">9.1 Property Path Syntax</a> from the SPARQL 1.1 specification doesn't allow variables in property paths. <pre><code>prefix : <https://stackoverflow.com/questions/19587520/sparql-path-between-two-instance/> select ?start ?end (count(?mid) as ?length) where { values (?start ?end) { (:a :c) (:d :g) } ?start :p+ ?mid . ?mid :p* ?end . } group by ?start ?end </code></pre> and get results like this: <pre><code>$ sparql --query query.rq --data data.n3 ------------------------ | start | end | length | ======================== | :d | :g | 3 | | :a | :c | 2 | ------------------------ </code></pre> A fuller description of what's happening here can be found in: <ul> <li><a href="https://stackoverflow.com/q/5198889/1281433">Calculate length of path between nodes?</a> (which is actually look at paths in a tree)</li> <li><a href="https://stackoverflow.com/a/18032019/1281433">this answer</a> to <a href="https://stackoverflow.com/q/18024413/1281433">Finding all steps in property path</a> (Note that the accepted answer says you can't do this, but the linked answer shows that you actually can); and</li> <li>the accepted answer to <a href="https://stackoverflow.com/q/17523804/1281433">Is it possible to get the position of an element in an RDF Collection in SPARQL?</a>.</li> </ul> The basic idea, though, is that if you have a path from <code>?start</code> to <code>?end</code>, then you've also got, for a bunch of different values of <code>?mid</code>, a path from <code>?start</code> to <code>?mid</code> and a path from <code>?mid</code> to <code>?end</code>. The number of different values that you can pick for <code>?mid</code> (if you allow one of the endpoints, and disallow the other) is exactly the length of the path.
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POpath between two resources
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. USCommunity
UserOwnerUserId
1. USJoshua Taylor
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. This table or related slice is empty.
CommentsPostId

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.