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<P>
<DIV class="title">SWI-Prolog Spatial Indexing</DIV>
<DIV class="author">Willem Robert van Hage <BR>
VU University Amsterdam <BR>
The Netherlands <BR>
E-mail: <A class="url" href="mailto:wrvhage@few.vu.nl">wrvhage@few.vu.nl</A></DIV>
<DIV class="abstract">
<DIV class="abstract-title">Abstract</DIV> SWI-Prolog interface to 
Spatial Index and GEOS libraries, providing spatial indexing of URI's. 
Supports import and export to GML, KML, and RDF with GeoRSS Simple, 
GeoRSS GML, and W3C WGS84 vocabulary properties.<BR>
<BR>
<B>Nota bene</B> that the spatialindex and GEOS C++ libraries have to be 
installed separately for this module to work.
</DIV>

<H1><A NAME="document-contents">Table of Contents</A></H1>

<DIV class="toc">
<DIV class="toc-h2"><A class="sec" href="#sec:1"><SPAN class="sec-nr">1</SPAN> <SPAN class="sec-title">Introduction</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="#sec:2"><SPAN class="sec-nr">2</SPAN> <SPAN class="sec-title">Shapes 
as Prolog Terms</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="#sec:3"><SPAN class="sec-nr">3</SPAN> <SPAN class="sec-title">Adding, 
Removing, and Bulkloading Shapes</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="#sec:4"><SPAN class="sec-nr">4</SPAN> <SPAN class="sec-title">Query 
types</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="#sec:5"><SPAN class="sec-nr">5</SPAN> <SPAN class="sec-title">Importing 
and Exporting Shapes</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="#sec:6"><SPAN class="sec-nr">6</SPAN> <SPAN class="sec-title">Integration 
of Space and Semantics</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="#sec:7"><SPAN class="sec-nr">7</SPAN> <SPAN class="sec-title">Architecture</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="#sec:7.1"><SPAN class="sec-nr">7.1</SPAN> <SPAN class="sec-title">Incremental 
Search and Non-determinism</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="#sec:8"><SPAN class="sec-nr">8</SPAN> <SPAN class="sec-title">Documentation</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="#sec:8.1"><SPAN class="sec-nr">8.1</SPAN> <SPAN class="sec-title">Library 
space/space -- Core spatial database</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="#sec:8.2"><SPAN class="sec-nr">8.2</SPAN> <SPAN class="sec-title">Library 
space/georss</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="#sec:8.3"><SPAN class="sec-nr">8.3</SPAN> <SPAN class="sec-title">Library 
space/wgs84</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="#sec:8.4"><SPAN class="sec-nr">8.4</SPAN> <SPAN class="sec-title">Library 
space/freebase</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="#sec:8.5"><SPAN class="sec-nr">8.5</SPAN> <SPAN class="sec-title">Library 
space/dbpedia</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="#sec:8.6"><SPAN class="sec-nr">8.6</SPAN> <SPAN class="sec-title">Library 
space/wkt</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="#sec:8.7"><SPAN class="sec-nr">8.7</SPAN> <SPAN class="sec-title">Library 
space/kml</SPAN></A></DIV>
<DIV class="toc-h3"><A class="sec" href="#sec:8.8"><SPAN class="sec-nr">8.8</SPAN> <SPAN class="sec-title">Library 
space/gml</SPAN></A></DIV>
<DIV class="toc-h2"><A class="sec" href="#sec:9"><SPAN class="sec-nr">9</SPAN> <SPAN class="sec-title">space_web_loader.pl</SPAN></A></DIV>
</DIV>

<P>

<H2><A NAME="sec:1"><SPAN class="sec-nr">1</SPAN> <SPAN class="sec-title">Introduction</SPAN></A></H2>

The Space package&nbsp;<CITE><A class="cite" href="#vanHage:2009">[1]</A></CITE> 
provides spatial indexing for SWI-Prolog. It is based on
<A class="url" href="http://geos.refractions.net/">Geometry Engine Open 
Source</A> and the <A class="url" href="http://trac.gispython.org/spatialindex/">Spatial 
Index Library</A>.

<H2><A NAME="sec:2"><SPAN class="sec-nr">2</SPAN> <SPAN class="sec-title">Shapes 
as Prolog Terms</SPAN></A></H2>

The central objects of the Space package are pairs, <VAR>&lt; u, s &gt;</VAR> 
of a URI, <VAR>u</VAR>, and its associated shape, <VAR>s</VAR>. The URIs 
are linked to the shapes with the <A NAME="idx:urishape2:1"></A><A class="pred" href="#uri_shape/2">uri_shape/2</A> 
predicate. We will support all OpenGIS Simple Features, points, 
linestrings, polygons (with <VAR>&gt;= 0</VAR> holes), multi-points, 
multi-polygons, and geometry collections; and some utility shapes like 
box and circle regions.<SUP class="fn">1<SPAN class="fn-text">The 
current version of the Space package, 0.1.2 , only supports points, 
linestrings, and polygons (with holes) and box regions. Development on 
the other (multi-)shape types is underway.</SPAN></SUP>

<P>Both the URIs and the shapes are represented as Prolog terms. This 
makes them first-class Prolog citizens, which allows the construction 
and transformation of shapes using regular Prolog clauses, or Definite 
Clause Grammars (DCGs). We support input from locations encoded in RDF 
with the <A class="url" href="http://www.w3.org/2003/01/geo/">W3C WGS84 
vocabulary</A> and with the <A class="url" href="http://georss.org">GeoRSS</A> 
Simple properties and the GeoRSS <CODE>where</CODE> property leading to 
an XML literal consisting of a GML element. The <A NAME="idx:urishape2:2"></A><A class="pred" href="#uri_shape/2">uri_shape/2</A> 
predicate searches for URI-Shape pairs in SWI-Prolog's RDF triple store. 
It matches URIs to Shapes by using WGS84 and GeoRSS properties. For 
example, a URI <VAR>u</VAR> is associated with the shape <VAR>s=</VAR><CODE>point(</CODE><VAR>lat,long</VAR><CODE>)</CODE> 
if the triple store contains the triples: <VAR>&lt; u,</VAR> <CODE>wgs84_pos:lat</CODE> <VAR>, 
lat &gt;</VAR> and <VAR>&lt; u,</VAR> <CODE>wgs84_pos:long</CODE> <VAR>, 
long &gt;</VAR>; or when it contains one of the following triples:<BR>
<VAR>&lt; u,</VAR> <CODE>georss:point</CODE><VAR>,</VAR><CODE>"</CODE><VAR>lat</VAR> <VAR>long</VAR><CODE>"</CODE><VAR>&gt;</VAR> 
or <VAR>&lt; u,</VAR> <CODE>georss:where</CODE><VAR>,</VAR><CODE>"&lt;gml:Point&gt;</CODE><CODE>&lt;gml:pos&gt;</CODE> <VAR>lat</VAR> <VAR>long</VAR><BR>
<CODE>&lt;/gml:pos&gt;</CODE><CODE>&lt;/gml:Point&gt;"</CODE><VAR>&gt;</VAR>. 
The XML literal containing the GML description of the geometric shape is 
parsed with a DCG that can also be used to generate GML from Prolog 
shape terms.

<PRE class="code">
?- shape(point(52.3325,4.8673)),
   shape(box(point(52.3324,4.8621),point(52.3348,4.8684))),
   shape(
   polygon([[point(52.3632,4.981)|_],    % the outer shell of the polygon
            [point(52.3631,4.9815)|_] |_ % any number of holes 0..*
           ])).
true.
%% uri_shape(?URI, ?Shape) is nondet.
?- uri_shape('http://www.example.org/myoffice', Shape).  % read from RDF
Shape = point(52.3325,4.8673).
</PRE>

<H2><A NAME="sec:3"><SPAN class="sec-nr">3</SPAN> <SPAN class="sec-title">Adding, 
Removing, and Bulkloading Shapes</SPAN></A></H2>

The spatial index can be modified in two ways: By inserting or 
retracting single URI-shape pairs respectively using the <A NAME="idx:spaceassert3:3"></A><A class="pred" href="#space_assert/3">space_assert/3</A>, 
or the <A NAME="idx:spaceretract3:4"></A><A class="pred" href="#space_retract/3">space_retract/3</A> 
predicate; or by loading many pairs at once using the <A NAME="idx:spacebulkload3:5"></A><SPAN class="pred-ext">space_bulkload/3</SPAN> 
predicate or its parameterless counterpart <A NAME="idx:spaceindexall0:6"></A><A class="pred" href="#space_index_all/0">space_index_all/0</A> 
which simply loads all the shapes it can find with the <A NAME="idx:urishape2:7"></A><A class="pred" href="#uri_shape/2">uri_shape/2</A> 
predicate into the default index. The former method is best for small 
manipulations of indices, while the latter method is best for the 
loading of large numbers of URI-shape pairs into an index. The Space 
package can deal with multiple indices to make it possible to divide 
sets of features. Indices are identified with a name handle, which can 
be any Prolog atom.<SUP class="fn">2<SPAN class="fn-text">Every 
predicate in the Space package that must be given an index handle also 
has an abbreviated version without the index handle argument which 
automatically uses the default index.</SPAN></SUP> The actual indexing 
of the shapes is performed using lazy evaluation. Assertions and 
retractions are put on a queue that belongs to an index. The queue is 
committed to the index whenever a query is performed, or when a 
different kind of modification is called for (<I>i.e.</I> when the queue 
contains assertions and a retraction is requested or vice versa).

<PRE class="code">
?- space_assert(ex:myoffice, point(52.3325,4.8673), demo_index).  % only adds it to the 'demo_index' queue
true.
?- space_contains(box(point(52.3324,4.8621), point(52.3348,4.8684)),
                  Cont, demo_index).
% uses 'demo_index', so triggers a call to space_index('demo_index').
Cont = 'http://www.example.org/myoffice' .    % first instantiation, etc.
</PRE>

<PRE class="code">
?- space_bulkload(space, uri_shape, demo_index).
true.
</PRE>

<PRE class="code">
% If the KML Geometry elements have an ID attribute,
% you can load them from a file, e.g. 'office.kml', like this:
?- space_bulkload(kml_file_uri_shape('office.kml'), 'demo_index').
% Added 12 URI-Shape pairs to demo_index 
true.

% You can insert the same objects one by one like this:
?- forall( kml_file_uri_shape('office.kml', Uri, Shape),
           space_assert(Uri, Shape, 'demo_index') ).
true.
</PRE>

<H2><A NAME="sec:4"><SPAN class="sec-nr">4</SPAN> <SPAN class="sec-title">Query 
types</SPAN></A></H2>

We chose three basic spatial query types as our basic building blocks: <EM>containment</EM>, <EM>intersection</EM>, 
and <EM>nearest neighbor</EM>. These three query types are implemented 
as pure Prolog predicates, respectively <A NAME="idx:spacecontains3:8"></A><A class="pred" href="#space_contains/3">space_contains/3</A>, <A NAME="idx:spaceintersects3:9"></A><A class="pred" href="#space_intersects/3">space_intersects/3</A>, 
and <A NAME="idx:spacenearest3:10"></A><A class="pred" href="#space_nearest/3">space_nearest/3</A>. 
These predicates work completely analogously, taking an index handle and 
a query shape to retrieve the URI of a shape matching the query, which 
is bound to the second argument. Any successive calls to the predicate 
try to re-instantiate the second argument with a different matching URI. 
The results of containment and intersection queries are instantiated in 
no particular order, while the nearest neighbor results are instantiated 
in order of increasing distance to the query shape. The <A NAME="idx:spacenearestbounded4:11"></A><SPAN class="pred-ext">space_nearest_bounded/4</SPAN> 
predicate is a containment query based on
<A NAME="idx:spacenearest3:12"></A><A class="pred" href="#space_nearest/3">space_nearest/3</A>, 
which returns objects within a certain range of the query shape in order 
of increasing distance.

<PRE class="code">
?- space_nearest(point(52.3325,4.8673), N, 'demo_index').
N = 'http://sws.geonames.org/2759113/' ;      % retry, ask for more
N = 'http://sws.geonames.org/2752058/' ;      % retry
N = 'http://sws.geonames.org/2754074/' .      % cut, satisfied
</PRE>

<H2><A NAME="sec:5"><SPAN class="sec-nr">5</SPAN> <SPAN class="sec-title">Importing 
and Exporting Shapes</SPAN></A></H2>

Besides supporting input from RDF we support input and output for other 
standards, like<A class="url" href="http://www.opengeospatial.org/standards/gml">GML</A>, <A class="url" href="http://code.google.com/apis/kml/">KML</A> 
and <A class="url" href="http://en.wikipedia.org/wiki/Well-known_text">WKT</A>. 
All shapes can be converted from and to these standards with the <A NAME="idx:gmlshape2:13"></A><A class="pred" href="#gml_shape/2">gml_shape/2</A>, <A NAME="idx:kmlshape2:14"></A><A class="pred" href="#kml_shape/2">kml_shape/2</A>, 
and <A NAME="idx:wktshape2:15"></A><A class="pred" href="#wkt_shape/2">wkt_shape/2</A> 
predicates.

<PRE class="code">
% Convert a WKT shape into GML and KML}
?- wkt_shape('POINT ( 52.3325 4.8673 )', Shape),  % instantiate from WKT
   gml_shape(GML, Shape),
   kml_shape(KML, Shape).
Shape = point(52.3325, 4.8673),
GML = '&lt;gml:Point&gt;&lt;gml:pos&gt;52.3325 4.8673&lt;/gml:pos&gt;&lt;/gml:Point&gt;',
KML = '&lt;Point&gt;&lt;coordinates&gt;4.8673,52.3325&lt;/coordinates&gt;&lt;/Point&gt;' .
</PRE>

<H2><A NAME="sec:6"><SPAN class="sec-nr">6</SPAN> <SPAN class="sec-title">Integration 
of Space and Semantics</SPAN></A></H2>

The non-deterministic implementation of the queries makes them behave 
like a lazy stream of solutions. This allows tight integration with 
other types of reasoning, like RDF(S) and OWL reasoning or other Prolog 
rules. An example of combined RDF and spatial reasoning is shown below.

<PRE class="code">
% Finds nearest railway stations in the province Utrecht (in GeoNames)
?- uri_shape(ex:myoffice, Office),
   rdf(Utrecht, geo:name, literal('Provincie Utrecht')),
   space_nearest(Office, Near),
   % 'S' stands for a spot, like a building, 'RSTN' for railway station
   rdf(Near, geo:featureCode, geo:'S.RSTN'),
   % 'Near' connected to 'Utrecht' by transitive 'parentFeature'
   rdf_reachable(Near, geo:parentFeature, Utrecht),
   rdf(Near, geo:name, literal(Name)),  % fetch name of 'Near'
   uri_shape(Near, Station),  % fetch shape of station
   % compute actual distance in km}
   space_distance_greatcircle(Office, Station, Distance, km).
Utrecht = 'http://sws.geonames.org/2745909/',  % first instantiation
Near = 'http://sws.geonames.org/6639765/',
Name = 'Station Abcoude' ,
Station = point(52.2761, 4.97904),
Distance = 9.85408 ;                           % etc.
Utrecht = 'http://sws.geonames.org/2745909/',  % second instantiation
Near = 'http://sws.geonames.org/6639764/',
Name = 'Station Breukelen' ,
Station = point(52.17, 4.9906),
Distance = 19.9199 .                           % etc.
</PRE>

<P>Integration of multiple spatial queries can be done in the same way. 
Since the queries return URIs an intermediate URI-Shape predicate is 
necessary to get a shape that can be used as a query. An example is 
shown below.

<PRE class="code">
% Find features inside nearby polygons.
?- uri_shape(ex:myoffice, Office),
   space_nearest(Office, NearURI),
   uri_shape(NearURI, NearShape),  % look up the shape of the URI 'Near'
   NearShape = polygon(_),  % assert that it must be a polygon}
   space_contains(NearShape, Contained).
</PRE>

<H2><A NAME="sec:7"><SPAN class="sec-nr">7</SPAN> <SPAN class="sec-title">Architecture</SPAN></A></H2>

<A NAME="sec:architecture"></A> The Space package consists of C++ and 
Prolog code. The main component is the Prolog module space.pl. All 
parsing and generation of input and output formats is done in Prolog. 
All index manipulation is done through the foreign language interface 
(FLI) from Prolog to C++. The <A NAME="idx:spacebulkload3:16"></A><SPAN class="pred-ext">space_bulkload/3</SPAN> 
predicate also communicates back across the FLI from C++ to Prolog, 
allowing the indexing functions to ask for candidates to index from the 
Prolog database, for example, by calling the <A NAME="idx:urishape2:17"></A><A class="pred" href="#uri_shape/2">uri_shape/2</A> 
predicate.

<H3><A NAME="sec:7.1"><SPAN class="sec-nr">7.1</SPAN> <SPAN class="sec-title">Incremental 
Search and Non-determinism</SPAN></A></H3>

The three search operations provided by the Space package all yield 
their results incrementally, <I>i.e.</I> one at a time. Prolog 
predicates actually do not have return values, but instantiate 
parameters. Multiple return values are returned by subsequently 
instantiating the same variable, so the first call to a predicate can 
make different variable instantiations than the second call. This 
standard support of non-deterministic behavior makes it easy to write 
incremental algorithms in Prolog.

<P>Internally, the search operations are handled by C++ functions that 
work on an R*-tree index from the Spatial Index Library <CITE><A class="cite" href="#Hadjieleftheriou:2005rz">[2]</A></CITE>. 
The C++ functions are accessed with the SWI-Prolog foreign language 
interface. To implement non-deterministic behavior the query functions 
have to store their state between successive calls and Prolog has to be 
aware which state is relevant to every call.

<P>Every search query creates an instance of a 
SpatialIndex::IQueryStrategy class (the 
IncrementalNearestNeighborStrategy class for INN queries, the 
IncrementalRangeQuery for containment and intersection queries). This 
class contains the search algorithm, accesses the R*-tree index, and 
stores the current state of the algorithm. For containment and 
intersection queries the results can be returned in any particular order 
so implementing non-deterministic behavior simply involves storing a 
pointer to a node in the R*-tree and returning every subsequent matching 
object. For nearest neighbor queries keeping state is slightly more 
complicated, because it is necessary to keep a priority queue of 
candidate results at all times to guarantee that the results are 
returned in order of increasing proximity.

<P>The Spatial Index library does not include an incremental nearest 
neighbor, so we implemented an adaptation of the algorithm described in <CITE><A class="cite" href="#Hjaltason:1999zi">[3]</A></CITE> 
as an IQueryStrategy. The original algorithm emits results, for example, 
with a callback function, without breaking from the search loop that 
finds all matches. Our adaptation breaks the search loop at every 
matching object and stores a handle to the state (including the priority 
queue) so that it can restart the search loop where it left off. This 
makes it possible to tie the query strategy into the non-deterministic 
foreign language interface of SWI-Prolog with very little time overhead. 
A pointer to the IQueryStrategy instance is stored on the Prolog stack, 
so that every successive call to the procedure knows with which query to 
continue.

<P>An alternative implementation would be to take the exact IncNearest 
algorithm described in <CITE><A class="cite" href="#Hjaltason:1999zi">[3]</A></CITE> 
and to emit the results into a queue. The Prolog stack would then 
contain a pointer to the queue. Every successive call would dequeue a 
result from the queue. This strategy is less time efficient, because of 
two reasons. It does not halt after each match, so it is less efficient 
when looking for few results. It requires two separate processes to run. 
One to find results, the other to poll the queue. This means there is 
some process management and communication overhead.

<H2><A NAME="sec:8"><SPAN class="sec-nr">8</SPAN> <SPAN class="sec-title">Documentation</SPAN></A></H2>

<H3><A NAME="sec:8.1"><SPAN class="sec-nr">8.1</SPAN> <SPAN class="sec-title">Library 
space/space -- Core spatial database</SPAN></A></H3>

<P><A NAME="sec:space"></A>

<DL>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="set_space/1"><STRONG>set_space</STRONG>(<VAR>+Option</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="set_space/2"><STRONG>set_space</STRONG>(<VAR>+IndexName, 
+Option</VAR>)</A></DT>
<DD class="defbody">
This predicate can be used to change the options of a spatial index (or 
de default index for <A class="pred" href="#set_space/1">set_space/1</A>). 
Some options, like rtree_storage(S) where S is disk or memory only have 
effect after clearing or bulkloading. Others, take effect immediately on 
a running index. More documentation will be provided in the near future.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_assert/3"><STRONG>space_assert</STRONG>(<VAR>+URI, 
+Shape, +IndexName</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_assert/2"><STRONG>space_assert</STRONG>(<VAR>+URI, 
+Shape</VAR>)</A></DT>
<DD class="defbody">
Insert <VAR>URI</VAR> with associated <VAR>Shape</VAR> in the queue to 
be inserted into the index with name <VAR>IndexName</VAR> or the default 
index. Indexing happens lazily at the next call of a query or manually 
by calling <A class="pred" href="#space_index/1">space_index/1</A>.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_retract/3"><STRONG>space_retract</STRONG>(<VAR>+URI, 
+Shape, +IndexName</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_retract/2"><STRONG>space_retract</STRONG>(<VAR>+URI, 
+Shape</VAR>)</A></DT>
<DD class="defbody">
Insert <VAR>URI</VAR> with associated <VAR>Shape</VAR> in the queue to 
be removed into the index with name <VAR>IndexName</VAR> or the default 
index. Indexing happens lazily at the next call of a query or manually 
by calling <A class="pred" href="#space_index/1">space_index/1</A>.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_index/1"><STRONG>space_index</STRONG>(<VAR>+IndexName</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_index/0"><STRONG>space_index</STRONG></A></DT>
<DD class="defbody">
Processes all asserts or retracts in the space queue for index
<VAR>IndexName</VAR> or the default index if no index is specified.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_clear/1"><STRONG>space_clear</STRONG>(<VAR>+IndexName</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_clear/0"><STRONG>space_clear</STRONG></A></DT>
<DD class="defbody">
Clears index <VAR>IndexName</VAR> or the default index if no index is 
specified, removing all of its contents.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_bulkload/2"><STRONG>space_bulkload</STRONG>(<VAR>:Closure, 
+IndexName</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_bulkload/1"><STRONG>space_bulkload</STRONG>(<VAR>:Closure</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_bulkload/0"><STRONG>space_bulkload</STRONG></A></DT>
<DD class="defbody">
Fast loading of many Shapes into the index <VAR>IndexName</VAR>.
<VAR>Closure</VAR> is called with two additional arguments: URI and 
Shape, that finds candidate URI-Shape pairs to index in the index <VAR>IndexName</VAR>.

<P><A class="pred" href="#space_bulkload/0">space_bulkload/0</A> 
defaults to <A class="pred" href="#uri_shape/2">uri_shape/2</A> for :<VAR>Closure</VAR>.

<DL>
<DT><B>See also</B><DD> the <A class="pred" href="#uri_shape/2">uri_shape/2</A> 
predicate for an example of a suitable functor.
</DL>

</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="space_contains/3"><STRONG>space_contains</STRONG>(<VAR>+Query, 
?Cont, +IndexName</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="space_contains/2"><STRONG>space_contains</STRONG>(<VAR>+Query, 
?Cont</VAR>)</A></DT>
<DD class="defbody">
Containment query. Unifies <VAR>Cont</VAR> with shapes contained in
<VAR>Query</VAR> Shape (or shape of <VAR>Query</VAR> URI) according to 
index
<VAR>IndexName</VAR> or the default index.</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="space_intersects/3"><STRONG>space_intersects</STRONG>(<VAR>+Query, 
?Inter, +IndexName</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="space_intersects/2"><STRONG>space_intersects</STRONG>(<VAR>+Query, 
?Inter</VAR>)</A></DT>
<DD class="defbody">
Intersection query. Unifies <VAR>Inter</VAR> with shapes intersecting 
with
<VAR>Query</VAR> Shape (or Shape of <VAR>Query</VAR> URI) according to 
index <VAR>IndexName</VAR> or the default index. (intersection subsumes 
containment)</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="space_nearest/3"><STRONG>space_nearest</STRONG>(<VAR>+Query, 
-Near, +IndexName</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="space_nearest/2"><STRONG>space_nearest</STRONG>(<VAR>+Query, 
-Near</VAR>)</A></DT>
<DD class="defbody">
Incremental Nearest-Neighbor query. Unifies <VAR>Near</VAR> with shapes 
in order of increasing distance to <VAR>Query</VAR> Shape (or Shape of <VAR>Query</VAR> 
URI) according to index <VAR>IndexName</VAR> or the default index.</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="uri_shape/2"><STRONG>uri_shape</STRONG>(<VAR>?URI, 
?Shape</VAR>)</A></DT>
<DD class="defbody">
Finds pairs of URIs and their corresponding Shapes based on WGS84 RDF 
properties (e.g. wgs84:lat), GeoRSS Simple properties (e.g. 
georss:polygon), and GeoRSS GML properties (e.g. georss:where).

<P><A class="pred" href="#uri_shape/2">uri_shape/2</A> is a dynamic 
predicate, which means it can be extended. If you use <A class="pred" href="#uri_shape/2">uri_shape/2</A> 
in this way, the <VAR>URI</VAR> argument has to be a canonical <VAR>URI</VAR>, 
not a QName.</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="uri_shape/3"><STRONG>uri_shape</STRONG>(<VAR>?URI, 
?Shape, +Source</VAR>)</A></DT>
<DD class="defbody">
Finds pairs of URIs and their corresponding Shapes using
<A class="pred" href="#uri_shape/2">uri_shape/2</A> from RDF that was 
loaded from a given <VAR>Source</VAR>.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_index_all/1"><STRONG>space_index_all</STRONG>(<VAR>+IndexName</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_index_all/0"><STRONG>space_index_all</STRONG></A></DT>
<DD class="defbody">
Loads all URI-Shape pairs found with <A class="pred" href="#uri_shape/2">uri_shape/2</A> 
into index <VAR>IndexName</VAR> or the default index name.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="shape/1"><STRONG>shape</STRONG>(<VAR>+Shape</VAR>)</A></DT>
<DD class="defbody">
Checks whether <VAR>Shape</VAR> is a valid supported shape.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_distance/3"><STRONG>space_distance</STRONG>(<VAR>+Point1, 
+Point2, -Distance</VAR>)</A></DT>
<DD class="defbody">
Calculates the distance between <VAR>Point1</VAR> and <VAR>Point2</VAR> 
by default using pythagorean distance.

<DL>
<DT><B>See also</B><DD>
<A class="pred" href="#space_distance_greatcircle/4">space_distance_greatcircle/4</A> 
for great circle distance.
</DL>

</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_distance_greatcircle/3"><STRONG>space_distance_greatcircle</STRONG>(<VAR>+Point1, 
+Point2, -Dist</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_distance_greatcircle/4"><STRONG>space_distance_greatcircle</STRONG>(<VAR>+Point1, 
+Point2, -Dist, +Unit</VAR>)</A></DT>
<DD class="defbody">
Calculates great circle distance between <VAR>Point1</VAR> and <VAR>Point2</VAR> 
in the specified <VAR>Unit</VAR>, which can take as a value km 
(kilometers) or nm (nautical miles). By default, nautical miles are 
used.
</DD>
</DL>

<H3><A NAME="sec:8.2"><SPAN class="sec-nr">8.2</SPAN> <SPAN class="sec-title">Library 
space/georss</SPAN></A></H3>

<P><A NAME="sec:georss"></A>

<DL>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="georss_candidate/2"><STRONG>georss_candidate</STRONG>(<VAR>?URI, 
?Shape</VAR>)</A></DT>
<DD class="defbody">
Finds <VAR>URI</VAR>-<VAR>Shape</VAR> pairs by searching for RDF triples 
that link <VAR>URI</VAR> to a <VAR>Shape</VAR> with GeoRSS RDF 
properties (e.g. georss:where, georss:line, georss:polygon). Both GeoRSS 
Simple and GML are supported.</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="georss_candidate/3"><STRONG>georss_candidate</STRONG>(<VAR>?URI, 
?Shape, +Source</VAR>)</A></DT>
<DD class="defbody">
Finds <VAR>URI</VAR>-<VAR>Shape</VAR> pairs using <A class="pred" href="#georss_candidate/2">georss_candidate/2</A> 
in RDF that was loaded from a certain <VAR>Source</VAR>.</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="georss_simple_candidate/2"><STRONG>georss_simple_candidate</STRONG>(<VAR>?URI, 
?Shape</VAR>)</A></DT>
<DD class="defbody">
Finds <VAR>URI</VAR>-<VAR>Shape</VAR> pairs by searching for GeoRSS 
Simple properties (e.g. georss:point, georss:line, georss:polygon) in 
the RDF database.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="georss_uri_shape_triple/5"><STRONG>georss_uri_shape_triple</STRONG>(<VAR>+URI, 
+Shape, -Subject, -Predicate, -Object</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="georss_uri_shape_triple/5"><STRONG>georss_uri_shape_triple</STRONG>(<VAR>-URI, 
-Shape, +Subject, +Predicate, +Object</VAR>)</A></DT>
<DD class="defbody">
Converts between a <VAR>URI</VAR>-<VAR>Shape</VAR> pair and its GeoRSS 
simple RDF triple form.</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="georss_gml_candidate/2"><STRONG>georss_gml_candidate</STRONG>(<VAR>?URI, 
?Shape</VAR>)</A></DT>
<DD class="defbody">
Finds <VAR>URI</VAR>-<VAR>Shape</VAR> pairs by searching for GeoRSS GML 
properties (i.e. georss:where) in the RDF database. Uses <A class="pred" href="#gml_shape/2">gml_shape/2</A> 
to parse the XMLLiteral representing the GML shape.
</DD>
</DL>

<H3><A NAME="sec:8.3"><SPAN class="sec-nr">8.3</SPAN> <SPAN class="sec-title">Library 
space/wgs84</SPAN></A></H3>

<P><A NAME="sec:wgs84"></A>

<DL>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="wgs84_candidate/2"><STRONG>wgs84_candidate</STRONG>(<VAR>?URI, 
?Point</VAR>)</A></DT>
<DD class="defbody">
Finds <VAR>URI</VAR>-Shape pairs of RDF resources that are place-tagged 
with W3C WGS84 properties (i.e. lat, long, alt).
<VAR>Point</VAR> = point(?Lat,?Long) ; <VAR>Point</VAR> = 
point(?Lat,?Long,?Alt).</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="wgs84_candidate/3"><STRONG>wgs84_candidate</STRONG>(<VAR>?URI, 
?Point, +Source</VAR>)</A></DT>
<DD class="defbody">
Finds <VAR>URI</VAR>-Shape pairs of RDF resources that are place-tagged 
with W3C WGS84 properties (i.e. lat, long, alt). From RDF that was 
loaded from a certain <VAR>Source</VAR>.</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="lat/2"><STRONG>lat</STRONG>(<VAR>?URI, 
?Lat</VAR>)</A></DT>
<DD class="defbody">
Finds the WGS84 latitude of resource <VAR>URI</VAR> (and vice versa) 
using the rdf_db index. <VAR>Lat</VAR> is a number.</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="long/2"><STRONG>long</STRONG>(<VAR>?URI, 
?Long</VAR>)</A></DT>
<DD class="defbody">
Finds the WGS84 longitude of resource <VAR>URI</VAR> (and vice versa) 
using the rdf_db index. <VAR>Long</VAR> is a number.</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="alt/2"><STRONG>alt</STRONG>(<VAR>?URI, 
?Alt</VAR>)</A></DT>
<DD class="defbody">
Finds the WGS84 altitude of resource <VAR>URI</VAR> (and vice versa) 
using the rdf_db index. <VAR>Alt</VAR> is a number.</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="coordinates/3"><STRONG>coordinates</STRONG>(<VAR>?URI, 
?Lat, ?Long</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="coordinates/4"><STRONG>coordinates</STRONG>(<VAR>?URI, 
?Lat, ?Long, ?Alt</VAR>)</A></DT>
<DD class="defbody">
Finds the WGS84 latitude, longitude and possibly altitude of resource <VAR>URI</VAR> 
(and vice versa) using the rdf_db index.
<VAR>Lat</VAR>, <VAR>Long</VAR>, and <VAR>Alt</VAR> are numbers.
</DD>
</DL>

<H3><A NAME="sec:8.4"><SPAN class="sec-nr">8.4</SPAN> <SPAN class="sec-title">Library 
space/freebase</SPAN></A></H3>

<P><A NAME="sec:freebase"></A>

<DL>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="freebase_candidate/2"><STRONG>freebase_candidate</STRONG>(<VAR>?URI, 
?Point</VAR>)</A></DT>
<DD class="defbody">
Finds <VAR>URI</VAR>-Shape pairs of RDF resource that are place-tagged 
with Freebase's location.location.geoposition notation that capture 
WGS84 latitude/longitude positions.</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="freebase_candidate/3"><STRONG>freebase_candidate</STRONG>(<VAR>?URI, 
?Point, ?Source</VAR>)</A></DT>
<DD class="defbody">
Finds <VAR>URI</VAR>-Shape pairs of RDF resource that are place-tagged 
with Freebase's location.location.geoposition notation that capture 
WGS84 latitude/longitude positions. From RDF that was loaded from a 
certain <VAR>Source</VAR>.
</DD>
</DL>

<H3><A NAME="sec:8.5"><SPAN class="sec-nr">8.5</SPAN> <SPAN class="sec-title">Library 
space/dbpedia</SPAN></A></H3>

<P><A NAME="sec:dbpedia"></A>

<DL>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="dbpedia_candidate/2"><STRONG>dbpedia_candidate</STRONG>(<VAR>?URI, 
?Point</VAR>)</A></DT>
<DD class="defbody">
Finds <VAR>URI</VAR>-Shape pairs of RDF resource that are place-tagged 
with DBpedia's coordinatenProperty notation that capture WGS84 
latitude/longitude positions.</DD>
<DT class="pubdef"><span class="pred-tag">[nondet]</span><A NAME="dbpedia_candidate/3"><STRONG>dbpedia_candidate</STRONG>(<VAR>?URI, 
?Point, ?Source</VAR>)</A></DT>
<DD class="defbody">
Finds <VAR>URI</VAR>-Shape pairs of RDF resource that are place-tagged 
with DBpedia's coordinatenProperty notation that capture WGS84 
latitude/longitude positions. From RDF that was loaded from a certain <VAR>Source</VAR>.
</DD>
</DL>

<H3><A NAME="sec:8.6"><SPAN class="sec-nr">8.6</SPAN> <SPAN class="sec-title">Library 
space/wkt</SPAN></A></H3>

<P><A NAME="sec:wkt"></A>

<DL>
<DT class="pubdef"><span class="pred-tag">[semidet]</span><A NAME="wkt_shape/2"><STRONG>wkt_shape</STRONG>(<VAR>?WKT, 
?Shape</VAR>)</A></DT>
<DD class="defbody">
Converts between the <VAR>WKT</VAR> serialization of a <VAR>Shape</VAR> 
and its native Prolog term representation.
</DD>
</DL>

<H3><A NAME="sec:8.7"><SPAN class="sec-nr">8.7</SPAN> <SPAN class="sec-title">Library 
space/kml</SPAN></A></H3>

<P><A NAME="sec:kml"></A>

<DL>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="kml_file_to_georss/1"><STRONG>kml_file_to_georss</STRONG>(<VAR>+KMLfile</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="kml_file_to_georss/2"><STRONG>kml_file_to_georss</STRONG>(<VAR>+KMLfile, 
+RDFfile</VAR>)</A></DT>
<DD class="defbody">
Converts the contents of an KML file into GeoRSS RDF in the RDF database 
of Prolog. The Geometries are converted to GeoRSS properties and values. 
Documents, Folders, etc. are ignored. MultiGeometry objects are expanded 
into separate simple Geometries. Geometries with an XML ID are assigned 
that ID as URI, other Geometries are assigned a RDF blank node. The 
kml:name and kml:description are translated to RDF properties.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="georss_to_kml_file/1"><STRONG>georss_to_kml_file</STRONG>(<VAR>+KMLfile</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="georss_to_kml_file/2"><STRONG>georss_to_kml_file</STRONG>(<VAR>+KMLfile, 
+Options</VAR>)</A></DT>
<DD class="defbody">
Converts the contents of the RDF database of Prolog into a KML file 
without style information and without Folders. kml:name and 
kml:description properties in the RDF database are converted to their 
KML counterparts.
<VAR>Options</VAR> can be used to pass Document level options, for 
example, the name of the dataset. <VAR>Options</VAR> can also include a 
graph(Graph) option to specify which RDF named graph should be converted 
to KML.</DD>
<DT class="pubdef"><span class="pred-tag">[semidet]</span><A NAME="kml_shape/2"><STRONG>kml_shape</STRONG>(<VAR>?Stream, 
?Shape</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[semidet]</span><A NAME="kml_shape/4"><STRONG>kml_shape</STRONG>(<VAR>?Stream, 
?Shape, ?Attributes, ?Content</VAR>)</A></DT>
<DD class="defbody">
Converts between the KML serialization of a shape and its internal 
Prolog term representation.
<VAR>Attributes</VAR> and <VAR>Content</VAR> can hold additional 
attributes and XML content elements of the KML, like ID, name, or 
styleUrl.</DD>
<DT class="pubdef"><span class="pred-tag">[semidet]</span><A NAME="kml_uri_shape/3"><STRONG>kml_uri_shape</STRONG>(<VAR>?KML, 
?URI, ?Shape</VAR>)</A></DT>
<DD class="defbody">
Converts between the <VAR>KML</VAR> serialization of a <VAR>URI</VAR>-shape 
pair and its internal Prolog term representation. It is assumed the <VAR>KML</VAR> 
Geometry element has a ID attribute specifying the <VAR>URI</VAR> of the 
shape. e.g.

<PRE class="code">
&lt;PointID="http://example.org/point1"&gt;&lt;coordinates&gt;52.37,4.89&lt;/coordinates&gt;&lt;/Point&gt;
</PRE>

</DD>
<DT class="pubdef"><span class="pred-tag">[semidet]</span><A NAME="kml_file_shape/2"><STRONG>kml_file_shape</STRONG>(<VAR>+File, 
?Shape</VAR>)</A></DT>
<DD class="defbody">
</DD>
<DT class="pubdef"><span class="pred-tag">[semidet]</span><A NAME="kml_file_shape/4"><STRONG>kml_file_shape</STRONG>(<VAR>+File, 
?Shape, ?Attributes, ?Content</VAR>)</A></DT>
<DD class="defbody">
Reads shapes from a KML file using <A class="pred" href="#kml_shape/2">kml_shape/2</A>.
<A class="pred" href="#kml_file_shape/4">kml_file_shape/4</A> also reads 
extra attributes and elements of the KML Geometry. e.g. <VAR>&lt;</VAR>Point 
targetId="NCName"<CODE>&gt;&lt;</CODE>extrude<VAR>&gt;</VAR>0<VAR>&lt;</VAR>/extrude<VAR>&gt;</VAR>...<VAR>&lt;</VAR>/Point<VAR>&gt;</VAR> 
will, besides parsing the Point, also instantiate <VAR>Content</VAR> 
with [extrude(0)] and <VAR>Attributes</VAR> with [targetId('NCName')].</DD>
<DT class="pubdef"><span class="pred-tag">[semidet]</span><A NAME="kml_file_uri_shape/3"><STRONG>kml_file_uri_shape</STRONG>(<VAR>+File, 
?URI, ?Shape</VAR>)</A></DT>
<DD class="defbody">
Reads <VAR>URI</VAR>-shape pairs from <VAR>File</VAR> using <SPAN class="pred-ext">kml_uri_shape/2</SPAN>.</DD>
<DT class="pubdef"><span class="pred-tag">[semidet]</span><A NAME="kml_save_header/2"><STRONG>kml_save_header</STRONG>(<VAR>+Stream, 
+Options</VAR>)</A></DT>
<DD class="defbody">
Outputs a KML header to <VAR>Stream</VAR>. This can be followed by calls 
to <A class="pred" href="#kml_save_shape/3">kml_save_shape/3</A> and
<A class="pred" href="#kml_save_footer/1">kml_save_footer/1</A>.

<P><VAR>Options</VAR> is an option list that can contain the option 
name(Name) specifying the Name of the document.

<DL>
<DT><B>To be done</B><DD> options to configure optional entities, like 
styles
</DL>

</DD>
<DT class="pubdef"><span class="pred-tag">[semidet]</span><A NAME="kml_save_shape/3"><STRONG>kml_save_shape</STRONG>(<VAR>+Stream, 
+Shape, +Options</VAR>)</A></DT>
<DD class="defbody">
Outputs a KML serialization of <VAR>Shape</VAR> to <VAR>Stream</VAR>. 
This can be preceded by a call to <A class="pred" href="#kml_save_header/2">kml_save_header/2</A> 
and followed by more calls to <A class="pred" href="#kml_save_shape/3">kml_save_shape/3</A> 
and a call to
<A class="pred" href="#kml_save_footer/1">kml_save_footer/1</A>.

<P><VAR>Options</VAR> is an option list that can contain the option 
attr(+List) or content(+List) that can be used to add additional 
attributes or xml element content to a shape. This can be used to 
specify things like the ID or name.

<P>Layout elements, like Placemark and Folder, have their own separate 
extra attributes to supply additional attributes and content. These can 
contain the special terms geom_attributes and geom_content that pass 
their content to the shape contained by the Placemark. For example, 
rendering a Placemark with the ID "placemark12" of an extruded Point 
shape with its URI as name of the Placemark and as ID of the shape and 
an additional styleUrl works as follows:

<PRE class="code">
kml_save_shape(Stream,
               placemark(point(53.0,3.9),
                         [ id(placemark12),
                           geom_attributes([ id(URI) ])
                         ],
                         [ name(URI),styleUrl(URI),
                           geom_content([ extrude(1) ])
                         ]),
               []).
</PRE>

</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="kml_save_footer/1"><STRONG>kml_save_footer</STRONG>(<VAR>+Stream</VAR>)</A></DT>
<DD class="defbody">
Outputs a KML footer to stream <VAR>Stream</VAR>. This can be preceded 
by calls to <A class="pred" href="#kml_save_header/2">kml_save_header/2</A> 
and
<A class="pred" href="#kml_save_shape/3">kml_save_shape/3</A>.
</DD>
</DL>

<H3><A NAME="sec:8.8"><SPAN class="sec-nr">8.8</SPAN> <SPAN class="sec-title">Library 
space/gml</SPAN></A></H3>

<P><A NAME="sec:gml"></A>

<DL>
<DT class="pubdef"><span class="pred-tag">[semidet]</span><A NAME="gml_shape/2"><STRONG>gml_shape</STRONG>(<VAR>?GML, 
?Shape</VAR>)</A></DT>
<DD class="defbody">
Converts between the <VAR>GML</VAR> serialization of a shape and its 
internal Prolog term representation.
</DD>
</DL>

<H2><A NAME="sec:9"><SPAN class="sec-nr">9</SPAN> <SPAN class="sec-title">space_web_loader.pl</SPAN></A></H2>

<P><A NAME="sec:spacewebloader"></A>

<DL>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_load_url/1"><STRONG>space_load_url</STRONG>(<VAR>+URL</VAR>)</A></DT>
<DD class="defbody">
Retrieve RDF over HTTP from a <VAR>URL</VAR>, load it in the rdf_db and 
index all URI-Shape pairs that can be found in it into the default 
index.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_load_url/2"><STRONG>space_load_url</STRONG>(<VAR>+URL, 
+Options</VAR>)</A></DT>
<DD class="defbody">
Load using <A class="pred" href="#space_load_url/1">space_load_url/1</A>, 
given extra options.

<DL>
<DT><STRONG>index</STRONG>(<VAR>+IndexName</VAR>)</DT>
<DD class="defbody">
Index the URI-Shape pairs into index named IndexName.
</DD>
<DT><STRONG>graph</STRONG>(<VAR>+Graph</VAR>)</DT>
<DD class="defbody">
Store the URI-Shape pairs in the named graph Graph. The pairs are 
recorded as uri_shape(URI,Shape,Graph).
</DD>
</DL>

</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_unload_url/1"><STRONG>space_unload_url</STRONG>(<VAR>+URL</VAR>)</A></DT>
<DD class="defbody">
Unload the RDF that was fetched from <VAR>URL</VAR> and remove all 
URI-Shape pairs that are contained in it from the default index.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_unload_url/2"><STRONG>space_unload_url</STRONG>(<VAR>+URL, 
+Options</VAR>)</A></DT>
<DD class="defbody">
Unload the RDF that was fetched from <VAR>URL</VAR> and remove all 
URI-Shape pairs that are contained in it. Accepts extra options:

<DL>
<DT><STRONG>index</STRONG>(<VAR>+IndexName</VAR>)</DT>
<DD class="defbody">
Remove from the index named IndexName.
</DD>
<DT><STRONG>graph</STRONG>(<VAR>+Graph</VAR>)</DT>
<DD class="defbody">
Remove the URI-Shape pairs from the named graph Graph.
</DD>
</DL>

</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_crawl_url/1"><STRONG>space_crawl_url</STRONG>(<VAR>+URL</VAR>)</A></DT>
<DD class="defbody">
Retrieve RDF over HTTP from a <VAR>URL</VAR>, load it in the rdf_db and 
index all URI-Shape pairs that can be found in it into the default 
index. Also attempt to resolve all URIs that appear as object in a 
link_property statement downloaded from the <VAR>URL</VAR>. Retrieve 
these URIs and process them in the same way. Iterate this process until 
there are no new links that have not already been crawled.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_crawl_url/2"><STRONG>space_crawl_url</STRONG>(<VAR>+URL, 
+Options</VAR>)</A></DT>
<DD class="defbody">
Crawl using <A class="pred" href="#space_crawl_url/1">space_crawl_url/1</A>, 
with additional options.

<DL>
<DT><STRONG>index</STRONG>(<VAR>+IndexName</VAR>)</DT>
<DD class="defbody">
Index the URI-Shape pairs into index named IndexName.
</DD>
<DT><STRONG>graph</STRONG>(<VAR>+Graph</VAR>)</DT>
<DD class="defbody">
Store the URI-Shape pairs in the named graph Graph. The pairs are 
recorded as uri_shape(URI,Shape,Graph).
</DD>
</DL>

</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_uncrawl_url/1"><STRONG>space_uncrawl_url</STRONG>(<VAR>+URL</VAR>)</A></DT>
<DD class="defbody">
Unload the RDF that was fetched from <VAR>URL</VAR> and remove all 
URI-Shape pairs that are contained in it from the default index. Also 
unload all data that were crawled by iteratively resolving the URIs 
linked to with a link_property.</DD>
<DT class="pubdef"><span class="pred-tag">[det]</span><A NAME="space_uncrawl_url/2"><STRONG>space_uncrawl_url</STRONG>(<VAR>+URL, 
+IndexName</VAR>)</A></DT>
<DD class="defbody">
Unload using <A class="pred" href="#space_uncrawl_url/1">space_uncrawl_url/1</A>, 
but remove the URI-Shape pairs from the index named <VAR>IndexName</VAR>.

<DL>
<DT><STRONG>index</STRONG>(<VAR>+IndexName</VAR>)</DT>
<DD class="defbody">
Remove the URI-Shape pairs from index named <VAR>IndexName</VAR>.
</DD>
<DT><STRONG>graph</STRONG>(<VAR>+Graph</VAR>)</DT>
<DD class="defbody">
Remove the URI-Shape pairs from the named graph Graph.
</DD>
</DL>

</DD>
</DL>

<H2>Bibliography</H2>

<DL class="bib"><DT class="bib"><A NAME="vanHage:2009"><STRONG>[1]</STRONG></A><DD class="bib">
Willem Robert van Hage, Jan Wielemaker and Guus Schreiber. The Space 
package: Tight Integration Between Space and Semantics.
<EM>Proceedings of the 8th International Semantic Web Conference 
Workshop: TerraCognita 2009.</EM></DD>
<DT class="bib"><A NAME="Hadjieleftheriou:2005rz"><STRONG>[2]</STRONG></A><DD class="bib">
Marios Hadjieleftheriou, Erik Hoel, and Vassilis&nbsp;J. Tsotras. Sail: 
A spatial index library for efficient application integration.
<EM>Geoinformatica</EM>, 9(4), 2005.</DD>
<DT class="bib"><A NAME="Hjaltason:1999zi"><STRONG>[3]</STRONG></A><DD class="bib">
G&iacute;sli&nbsp;R. Hjaltason and Hanan Samet. Distance browsing in 
spatial databases.
<EM>ACM Transactions on Database Systems (TODS)</EM>, 24(2):265--318, 
1999.

<P></DD>
</DL>

<H1><A NAME="document-index">Index</A></H1>

<DL>
<DT><STRONG>A</STRONG></DT>
<DD>
</DD>
<DT><A class="idx" href="#alt/2">alt/2</A></DT>
<DD>
</DD>
<DT><STRONG>C</STRONG></DT>
<DD>
</DD>
<DT><A class="idx" href="#coordinates/3">coordinates/3</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#coordinates/4">coordinates/4</A></DT>
<DD>
</DD>
<DT><STRONG>D</STRONG></DT>
<DD>
</DD>
<DT><A class="idx" href="#dbpedia_candidate/2">dbpedia_candidate/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#dbpedia_candidate/3">dbpedia_candidate/3</A></DT>
<DD>
</DD>
<DT><STRONG>F</STRONG></DT>
<DD>
</DD>
<DT><A class="idx" href="#freebase_candidate/2">freebase_candidate/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#freebase_candidate/3">freebase_candidate/3</A></DT>
<DD>
</DD>
<DT><STRONG>G</STRONG></DT>
<DD>
</DD>
<DT><A class="idx" href="#georss_candidate/2">georss_candidate/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#georss_candidate/3">georss_candidate/3</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#georss_gml_candidate/2">georss_gml_candidate/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#georss_simple_candidate/2">georss_simple_candidate/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#georss_to_kml_file/1">georss_to_kml_file/1</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#georss_to_kml_file/2">georss_to_kml_file/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#georss_uri_shape_triple/5">georss_uri_shape_triple/5</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#gml_shape/2">gml_shape/2</A></DT>
<DD>
<A class="idx" href="#idx:gmlshape2:13">5</A></DD>
<DT><STRONG>K</STRONG></DT>
<DD>
</DD>
<DT><A class="idx" href="#kml_file_shape/2">kml_file_shape/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#kml_file_shape/4">kml_file_shape/4</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#kml_file_to_georss/1">kml_file_to_georss/1</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#kml_file_to_georss/2">kml_file_to_georss/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#kml_file_uri_shape/3">kml_file_uri_shape/3</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#kml_save_footer/1">kml_save_footer/1</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#kml_save_header/2">kml_save_header/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#kml_save_shape/3">kml_save_shape/3</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#kml_shape/2">kml_shape/2</A></DT>
<DD>
<A class="idx" href="#idx:kmlshape2:14">5</A></DD>
<DT><A class="idx" href="#kml_shape/4">kml_shape/4</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#kml_uri_shape/3">kml_uri_shape/3</A></DT>
<DD>
</DD>
<DT><STRONG>L</STRONG></DT>
<DD>
</DD>
<DT><A class="idx" href="#lat/2">lat/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#long/2">long/2</A></DT>
<DD>
</DD>
<DT><STRONG>S</STRONG></DT>
<DD>
</DD>
<DT><A class="idx" href="#set_space/1">set_space/1</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#set_space/2">set_space/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#shape/1">shape/1</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_assert/2">space_assert/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_assert/3">space_assert/3</A></DT>
<DD>
<A class="idx" href="#idx:spaceassert3:3">3</A></DD>
<DT><A class="idx" href="#space_bulkload/0">space_bulkload/0</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_bulkload/1">space_bulkload/1</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_bulkload/2">space_bulkload/2</A></DT>
<DD>
</DD>
<DT>space_bulkload/3</DT>
<DD>
<A class="idx" href="#idx:spacebulkload3:5">3</A> <A class="idx" href="#idx:spacebulkload3:16">7</A></DD>
<DT><A class="idx" href="#space_clear/0">space_clear/0</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_clear/1">space_clear/1</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_contains/2">space_contains/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_contains/3">space_contains/3</A></DT>
<DD>
<A class="idx" href="#idx:spacecontains3:8">4</A></DD>
<DT><A class="idx" href="#space_crawl_url/1">space_crawl_url/1</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_crawl_url/2">space_crawl_url/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_distance/3">space_distance/3</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_distance_greatcircle/3">space_distance_greatcircle/3</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_distance_greatcircle/4">space_distance_greatcircle/4</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_index/0">space_index/0</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_index/1">space_index/1</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_index_all/0">space_index_all/0</A></DT>
<DD>
<A class="idx" href="#idx:spaceindexall0:6">3</A></DD>
<DT><A class="idx" href="#space_index_all/1">space_index_all/1</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_intersects/2">space_intersects/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_intersects/3">space_intersects/3</A></DT>
<DD>
<A class="idx" href="#idx:spaceintersects3:9">4</A></DD>
<DT><A class="idx" href="#space_load_url/1">space_load_url/1</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_load_url/2">space_load_url/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_nearest/2">space_nearest/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_nearest/3">space_nearest/3</A></DT>
<DD>
<A class="idx" href="#idx:spacenearest3:10">4</A> <A class="idx" href="#idx:spacenearest3:12">4</A></DD>
<DT>space_nearest_bounded/4</DT>
<DD>
<A class="idx" href="#idx:spacenearestbounded4:11">4</A></DD>
<DT><A class="idx" href="#space_retract/2">space_retract/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_retract/3">space_retract/3</A></DT>
<DD>
<A class="idx" href="#idx:spaceretract3:4">3</A></DD>
<DT><A class="idx" href="#space_uncrawl_url/1">space_uncrawl_url/1</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_uncrawl_url/2">space_uncrawl_url/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_unload_url/1">space_unload_url/1</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#space_unload_url/2">space_unload_url/2</A></DT>
<DD>
</DD>
<DT><STRONG>U</STRONG></DT>
<DD>
</DD>
<DT><A class="idx" href="#uri_shape/2">uri_shape/2</A></DT>
<DD>
<A class="idx" href="#idx:urishape2:1">2</A> <A class="idx" href="#idx:urishape2:2">2</A> <A class="idx" href="#idx:urishape2:7">3</A> <A class="idx" href="#idx:urishape2:17">7</A></DD>
<DT><A class="idx" href="#uri_shape/3">uri_shape/3</A></DT>
<DD>
</DD>
<DT><STRONG>W</STRONG></DT>
<DD>
</DD>
<DT><A class="idx" href="#wgs84_candidate/2">wgs84_candidate/2</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#wgs84_candidate/3">wgs84_candidate/3</A></DT>
<DD>
</DD>
<DT><A class="idx" href="#wkt_shape/2">wkt_shape/2</A></DT>
<DD>
<A class="idx" href="#idx:wktshape2:15">5</A></DD>
</DL>

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