gv_perl - graph manipulation in perl

Newgraphs

       New empty graph
              graph_handlegv::graph(name);graph_handlegv::digraph(name);graph_handlegv::strictgraph(name);graph_handlegv::strictdigraph(name);

       New graph from a dot-syntax string or file
              graph_handlegv::readstring(string);graph_handlegv::read(stringfilename);graph_handlegv::read(channel);

       Add new subgraph to existing graph
              graph_handlegv::graph(graph_handle,name);Newnodes

       Add new node to existing graph
              node_handlegv::node(graph_handle,name);Newedges

       Add new edge between existing nodes
              edge_handlegv::edge(tail_node_handle,head_node_handle);

       Add a new edge between an existing tail node, and a named head node which will be induced in the graph if
       it doesn't already exist
              edge_handlegv::edge(tail_node_handle,head_name);

       Add a new edge between an existing head node, and a named tail node which will be induced in the graph if
       it doesn't already exist
              edge_handlegv::edge(tail_name,head_node_handle);

       Add a new edge between named tail  and head nodes which will be induced in the graph if they don't
       already exist
              edge_handlegv::edge(graph_handle,tail_name,head_name);Settingattributevalues

       Set value of named attribute of graph/node/edge - creating attribute if necessary
              stringgv::setv(graph_handle,attr_name,attr_value);stringgv::setv(node_handle,attr_name,attr_value);stringgv::setv(edge_handle,attr_name,attr_value);

       Set value of existing attribute of graph/node/edge (using attribute handle)
              stringgv::setv(graph_handle,attr_handle,attr_value);stringgv::setv(node_handle,attr_handle,attr_value);stringgv::setv(edge_handle,attr_handle,attr_value);Gettingattributevalues

       Get value of named attribute of graph/node/edge
              stringgv::getv(graph_handle,attr_name);stringgv::getv(node_handle,attr_name);stringgv::getv(edge_handle,attr_name);

       Get value of attribute of graph/node/edge (using attribute handle)
              stringgv::getv(graph_handle,attr_handle);stringgv::getv(node_handle,attr_handle);stringgv::getv(edge_handle,attr_handle);Obtainnamesfromhandlesstringgv::nameof(graph_handle);stringgv::nameof(node_handle);stringgv::nameof(attr_handle);Findhandlesfromnamesgraph_handlegv::findsubg(graph_handle,name);node_handlegv::findnode(graph_handle,name);edge_handlegv::findedge(tail_node_handle,head_node_handle);attribute_handlegv::findattr(graph_handle,name);attribute_handlegv::findattr(node_handle,name);attribute_handlegv::findattr(edge_handle,name);Miscgraphnavigatorsreturninghandlesnode_handlegv::headof(edge_handle);node_handlegv::tailof(edge_handle);graph_handlegv::graphof(graph_handle);graph_handlegv::graphof(edge_handle);graph_handlegv::graphof(node_handle);graph_handlegv::rootof(graph_handle);Obtainhandlesofprotonode/edgeforsettingdefaultattributevaluesnode_handlegv::protonode(graph_handle);edge_handlegv::protoedge(graph_handle);Iterators

       Iteration termination tests
              boolgv::ok(graph_handle);boolgv::ok(node_handle);boolgv::ok(edge_handle);boolgv::ok(attr_handle);

       Iterate over subgraphs of a graph
              graph_handlegv::firstsubg(graph_handle);graph_handlegv::nextsubg(graph_handle,subgraph_handle);

       Iterate over supergraphs of a graph (obscure and rarely useful)
              graph_handlegv::firstsupg(graph_handle);graph_handlegv::nextsupg(graph_handle,subgraph_handle);

       Iterate over edges of a graph
              edge_handlegv::firstedge(graph_handle);edge_handlegv::nextedge(graph_handle,edge_handle);

       Iterate over outedges of a graph
              edge_handlegv::firstout(graph_handle);edge_handlegv::nextout(graph_handle,edge_handle);

       Iterate over edges of a node
              edge_handlegv::firstedge(node_handle);edge_handlegv::nextedge(node_handle,edge_handle);

       Iterate over out-edges of a node
              edge_handlegv::firstout(node_handle);edge_handlegv::nextout(node_handle,edge_handle);

       Iterate over head nodes reachable from out-edges of a node
              node_handlegv::firsthead(node_handle);node_handlegv::nexthead(node_handle,head_node_handle);

       Iterate over in-edges of a graph
              edge_handlegv::firstin(graph_handle);edge_handlegv::nextin(node_handle,edge_handle);

       Iterate over in-edges of a node
              edge_handlegv::firstin(node_handle);edge_handlegv::nextin(graph_handle,edge_handle);

       Iterate over tail nodes reachable from in-edges of a node
              node_handlegv::firsttail(node_handle);node_handlegv::nexttail(node_handle,tail_node_handle);

       Iterate over nodes of a graph
              node_handlegv::firstnode(graph_handle);node_handlegv::nextnode(graph_handle,node_handle);

       Iterate over nodes of an edge
              node_handlegv::firstnode(edge_handle);node_handlegv::nextnode(edge_handle,node_handle);

       Iterate over attributes of a graph
              attribute_handlegv::firstattr(graph_handle);attribute_handlegv::nextattr(graph_handle,attr_handle);

       Iterate over attributes of an edge
              attribute_handlegv::firstattr(edge_handle);attribute_handlegv::nextattr(edge_handle,attr_handle);

       Iterate over attributes of a node
              attribute_handlegv::firstattr(node_handle);attribute_handlegv::nextattr(node_handle,attr_handle);Removegraphobjectsboolgv::rm(graph_handle);boolgv::rm(node_handle);boolgv::rm(edge_handle);Layout

       Annotate a graph with layout attributes and values using a specific layout engine
              boolgv::layout(graph_handle,stringengine);Render

       Render a layout into attributes of the graph
              boolgv::render(graph_handle);

       Render a layout to stdout
              boolgv::render(graph_handle,stringformat);

       Render to an open file
              boolgv::render(graph_handle,stringformat,channelfout);

       Render a layout to an unopened file by name
              boolgv::render(graph_handle,stringformat,stringfilename);

       Render to a string result
              stringgv::renderresult(graph_handleing,stringformat);gv::renderresult(graph_handle,stringformat,stringoutdata);

       Render to an open channel
              boolgv::renderchannel(graph_handle,stringformat,stringchannelname);

       Render a layout to a malloc'ed string, to be free'd by the caller

       (deprecated - too easy to leak memory)

       (still needed for "eval [gv::renderdata $G tk]" )
              stringgv::renderdata(graph_handle,stringformat);

       Writing graph back to file
              boolgv::write(graph_handle,stringfilename);boolgv::write(graph_handle,channel);

       Graph transformation tools
              boolgv::tred(graph_handle);

gv_perl  is  a  dynamically  loaded  extension  for  perl that provides access to the graph facilities of
       graphviz.

       graph, dot, neato, fdp, circo, twopi, perl.

                                                   22 May 2025                                         gv(3perl)

       gv_perl - graph manipulation in perl

       #!/usr/bin/perl
       use gv;