README

An RDF library for PHP implementing the https://github.com/sweetrdf/rdfInterface interface.

The aim was to provide as simple, short and clear implementation as possible. Performance wasn't really important (see the Performance chapter below).

It can be used as a baseline for testing performance of other libraries as well for testing interoperability of the rdfInterface implementations (e.g. making sure they work correctly with rdfInterface\Term objects created by other library).

Installation

Obtain the Composer
Run composer require sweetrdf/simple-rdf
Run composer require sweetrdf/quick-rdf-io to install parsers and serializers.

Automatically generated documentation

https://sweetrdf.github.io/simpleRdf/namespaces/simplerdf.html

It's very incomplete but better than nothing.
RdfInterface documentation is included which explains the most important design decisions.

Usage

(you can also take a look at generic rdfInterface examples)

include 'vendor/autoload.php';

use simpleRdf\DataFactory as DF;

$graph = new simpleRdf\Dataset();
$parser = new quickRdfIo\TriGParser(new simpleRdf\DataFactory());
$stream = fopen('pathToTurtleFile', 'r');
$graph->add($parser->parseStream($stream));
fclose($stream);

// count edges in the graph
echo count($graph);

// go trough all edges in the graph
foreach ($graph as $i) {
  echo "$i\n";
}

// find all graph edges with a given subject
echo $graph->copy(DF::quadTemplate(DF::namedNode('http://mySubject')));

// find all graph edges with a given predicate
echo $graph->copy(DF::quadTemplate(null, DF::namedNode('http://myPredicate')));

// find all graph edges with a given object
echo $graph->copy(DF::quadTemplate(null, null, DF::literal('value', 'en')));

// replace an edge in the graph
$edge = DF::quad(DF::namedNode('http://edgeSubject'), DF::namedNode('http://edgePredicate'), DF::namedNode('http://edgeObject'));
$graph[$edge] = $edge->withObject(DF::namedNode('http://anotherObject'));

// find intersection with other graph
$graph->copy($otherGraph); // immutable
$graph->delete($otherGraph); // in-place

// compute union with other graph
$graph->union($otherGraph); // immutable
$graph->add($otherGraph); // in-place

// compute set difference with other graph
$graph->copyExcept($otherGraph); // immutable
$graph->delete($otherGraph); // in-place

$serializer = new quickRdfIo\TurtleSerializer();
$stream = fopen('pathToOutputTurtleFile', 'w');
$serializer->serializeStream($stream, $graph);
fclose($stream);

Performance

The simpleRdf\Dataset class shouldn't be used to deal with larger amounts of quads.

Adding a quad has computational complexity of O(N) where N is the number of quads in the dataset. It means adding n quads has computational complexity of O(n!) (read - it quickly gets out of hand with larger n).

Just a sample results:

quads count	execution time [s]	relative quads count	relative execution time
125	0.018090	1	1.0
250	0.059559	2	3.3
500	0.210958	4	11.7
1000	0.849956	8	47.0
2000	2.941319	16	162.6
4000	10.697164	32	591.3
8000	45.792556	64	2531.4

You get the idea, don't you?

Other operations are also not performant, e.g. all searches and in-place deletions have complexity of O(N) and all methods returning a new copy of the dataset have complexity of O(N) + O(n!) (where N is number of quads in the dataset and n the number of quads in the returned dataset).

If you are looking for a performant implementation, please take a look at the quickRdf.

sweetrdf / simple-rdf

Maintainers

Details

README

Installation

Automatically generated documentation

Usage

Performance