Class hierarchy¶

To explore your data, navigate to Explore -> Class hierarchy. You can see a diagram depicting the hierarchy of the imported RDF classes by the number of instances. The biggest circles are the parent classes and the nested ones are their children.

Domain-range graph¶

To see all properties of a given class as well as their domain and range, double click its class circle or the Domain-Range Graph button from the side panel. The RDF Domain-Range Graph view opens, enabling you to further explore the class connectedness by clicking the green nodes (object property class).

• To administer your graph view, use the toolbar options on the right-hand side of the screen.

  
  • To go back to your class in the RDF Class hierarchy, click the Back to Class hierarchy diagram button.
  • To export the diagram as an .svg image, click the Export Diagram download icon.

Class relationships¶

To explore the relationships between the classes, navigate to Explore -> Class relationships. You can see a complicated diagram which by default is showing only the top relationships. Each of them is a bundle of links between the individual instances of two classes. Each link is an RDF statement where the subject is an instance of one class, the object is an instance of another class, and the link is the predicate. Depending on the number of links between the instances of two classes, the bundle can be thicker or thinner and gets the color of the class with more incoming links. These links can be in both directions. Note that contrary to the Class hierarchy, the Class relationships diagram is based on the real statements between classes, not on the Ontology schema.

In the example below, you can see that Person is the class with the biggest number of links. It is very strongly connected to Feature and City and most of the links are from Person. Also, you notice that all classes have many outgoing links to opengis:_Feature.

Left to the diagram you can see a list of all classes ordered by the links they have and an indicator of the direction of the links. Click on it to see the actual classes this class is linked to, again ordered by the number of links with the actual number shown. Also, the direction of the links is displayed.

Use the list of classes to control which classes to see in the diagram with the add/remove icons next to each class. Remove all classes by the rubber icon. The green background of a class indicates that the class is present in the diagram. You see that Person has much more connections to City than Village.

For each two classes in the diagram you can find the top predicates that connect them, again ordered and with the number of statements of this predicate and instances of these classes. Person is linked to City by the birthPlace and deathPlace predicates.

All these statistics are built on top of the whole repository so when you have a lot of data, the building of the diagram may be very slow. Please, be patient in that case.

Explore resources¶

To explore the graph of your data, navigate to Explore -> Visual graph. You see a search input to choose a resource as a starting point for graph exploration.

A graph of the resource links is shown. Nodes that have the same type have the same color. All types for a node are listed when you hover it. By default, what you see are the first 20 links to other resources ordered by RDF rank if present. See the settings bellow to modify this limit and the types and predicates to hide or see with preference.

The size of the nodes reflects the importance of the node by RDF rank. Expand further by clicking on a node of interest. A menu appears. Click the expand icon to see the links for the chosen node.

Click the info icon in the node menu to know more about a resource.

Once a node is expanded, you have the option to collapse it. This will remove all its links and their nodes, except those that are connected to other nodes also. See the example bellow. Collapsing “Eastern European Time” removes all nodes except Bulgaria, because Bulgaria is also linked to Sofia which is expanded.

If you are not interested in a node anymore, you can hide it using the remove icon, which removes not only node links but the node itself. The focus icon is used to restart the graph with the node of interested. Use carefully, since it resets the state of the graph.

More global actions are available in the menu in the upper right corner. Use the arrows to rotate visually your graph for convenience.

Click on the settings icon to configure your graph globally.

Add for example http://dbpedia.org/ontology/Person as preferred type and tick the option to see only preferred types. Only links to Person instances are shown, related to Sofia.

Viewing and editing resources¶

View and add a resource¶

To view a resource in the repository, go to Explore -> View resource and enter the URI of a resource or navigate to it by clicking the SPARQL results links.

Viewing resources provides an easy way to see triples where a given URI is the subject, predicate or object.

Even when the resource is not in the database, you can still add it from the resource view.

Here, you can create as many triples as you need for it, using the resource edit. To add a triple, fill in the necessary fields and click the tick, next to the last one.

To view the new statements in TriG, click the View TriG button.

When ready, save the new resource to the repository.

Edit a resource¶

Once you open a resource in View resource, you can also edit it. Click the edit icon next to the resource namespace and add, change or delete the properties of this resource.

Note

You cannot change or delete the inferred statements.