rdf_graphviz.pl -- Interface to graphviz for RDF graphs

Graphviz is a general purpose graph vizualization library. Its home-page is http://www.graphviz.org/ This module translates an RDF graph represented as a list of rdf(S,P,O) into a .dot file.

author: - Jan Wielemaker

gviz_write_rdf(+Stream, +Graph, +Options) is det

Write the graph Triples to Stream in dot compatible format. Options:

graph_attributes(+Attributes)

Additional overall graphs attributes for dot. Each attribute is of the format Name(Value) and written as Name="Value". The term size(W,H) is accepted as well.

max_label_length(+Len)

Truncate labels to Len characters. Default is 25. Use inf to print the full label.

lang(+Lang)

Lang is the language used for the labels. See resource_label/4.

smash(+Properties)

Smash networks connected by one of the given properties. Currently only [owl:sameAs].

bags(Bags)

How to handle bags. Values are

graph: Show as normal nodes (i.e. handles as normal RDF)
merge(Shape, Max): Put the members in a dot node using Shape. Only place the first Max members and add a note stating '... showing N of M' to indicate the actual number

edge_links(+Boolean)

If false (default true) do not put href atributes on edges.

wrap_url(:Goal)

If present, URLs of the graph are replaced with the result of call(Goal, URL0, URL)

edge_hook(:Goal)

Called to define the attributes for a link as call(Goal, URI, Attributes, Options). Attributes is a list of Name(Value) terms. See edge_attributes/3.

shape_hook(:Goal)

Called to define the shape of a resource as

call(Goal, URI,
Shape, Options)

. Shape is a list of Name(Value) terms. See shape/3.

bag_shape_hook(:Goal)

Called to define the shape parameters for a bag (Table). called as call(Goal, Members, Shape) Shape is a list of Name(Value) terms.

label_hook(:Goal)

Called to define the label of a resource as

call(Goal, URI,
Language, MaxLength, Label)

. Label is an atom.

target(Target)

If present, add target=Target to all attribute lists that have an href attribute.

display_lang(+Boolean)

Display the language of literal nodes, defaults to true.

write_graph_attributes(+List, +Out)[private]

Write attributes for the graph as a whole

combine_bags(+Graph, -Triples, -Bags, +Options) is det[private]

Seperate the bags from the graph. Triples represent the remaining graph (in which a bag is a single node) and Bags is an assoc BagID-Members storing the members of the bags.

bagid_property(+P, -I) is semidet[private]

True if P is of the format _:N, where N is a non-negative integer.

smash_graph(+GraphIn, -GraphOut, +Options)[private]

Smash networks of equivalent properties.

smash_on_property(+P, +GraphIn, -GraphOut)[private]

Merge owl:sameAs nodes, replacing the node with a bag.

gv_write_edges(+Graph, -Done, +Stream, +Options) is det[private]

Write the edges of an RDF graph in dot format. It invents a dot identifier for each node as it processes the nodes. The mapping from node to dot identifier is returned in the assoc Done.

gv_write_nodes(+Nodes:list(pair), +Stream, +Options)[private]

Write information about the nodes, defining the share and label of the node.

write_node_attributes(+RDF, +Stream, +Options) is det[private]

Write attributes for an RDF node. The node identifier matching the declared edges is alreadu written to Stream.

bag_label(+Members, +Max, -Label, +Options) is det[private]

Create an HTML description for describing a bag of objects.

Arguments:

`Max`	- is the maximum # members to show. If there are more, a text "... showing N of M" is displayed.
`Label`	- is a Prolog packed string with HTML text.

write_image_node(+ImgAttrs, +Attrs, +Stream, +Options) is det[private]

Render a node using an image. The image location is either an external URL or a local file specification using the notation icons(File), a term that must resolve in an image file using absolute_file_name/3. In the default setup, this means that the image must be in the directory web/icons of a package.

resource_label(+Resource, -Label:atom, +Options) is det[private]

Label is the textual label to show for Resource. Process the options

lang(+Lang)
max_label_length(+Len)

write_attributes(+Attributes:list, +Out:stream) is det[private]

Write attribute values. We define some special attributes:

html(HTML): Emit as label=<HTML>

filter_attributes(+AllAttrs, +Element, -ForElement, -Rest) is det[private]

gv_attr(?AttrName, ?Element, ?Type) is nondet[private]

Name and type-declarations for GraphViz attributes. Types are defined my must_be/2.

See also: - http://www.graphviz.org/doc/info/shapes.html

cstring(+Codes)//[private]

Create a C-string. Normally dot appears to be using UTF-8 encoding. Would there be a safer way to transport non-ascii characters, such as \uXXXX?

bag_shape(+Members, -BagShape, +Options) is det[private]

Compute parameters for a bag of resources.

shape(+Resource, -Attributes, +Options) is det[private]

Shape is the shape of the node to use for Resource. Shapes can be modified in two ways:

through the option shape_hook(Closure), which must return a valid Attributes list for GraphViz
By addings sub-properties of graphviz:styleParameter to the class of the resource. The value of this property defines the attribute value, while the label defines the attribute-name.

edge_attributes(+Triple, -Attributes, +Options) is det[private]

Arguments:

Triple - is a term rdf(S,P,O).

cached_image_in_svg(+Request)[private]

HTTP handler to serve an image we have included in an SVG file.

To be done: - Should we restrict files served to files that are part of recently served SVG files?