gv(3lua) gv(3lua) NAME gv_lua - graph manipulation in lua SYNOPSIS #!/usr/bin/lua require('gv') USAGE INTRODUCTION gv_lua is a dynamically loaded extension for lua that provides access to the graph facilities of graphviz. COMMANDS New graphs New empty graph graph_handle gv.graph (name); graph_handle gv.digraph (name); graph_handle gv.strictgraph (name); graph_handle gv.strictdigraph (name); New graph from a dot-syntax string or file graph_handle gv.readstring (string); graph_handle gv.read (string filename); graph_handle gv.read (channel); Add new subgraph to existing graph graph_handle gv.graph (graph_handle, name); New nodes Add new node to existing graph node_handle gv.node (graph_handle, name); New edges Add new edge between existing nodes edge_handle gv.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_handle gv.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_handle gv.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_handle gv.edge (graph_handle, tail_name, head_name); Setting attribute values Set value of named attribute of graph/node/edge - creating attribute if necessary string gv.setv (graph_handle, attr_name, attr_value); string gv.setv (node_handle, attr_name, attr_value); string gv.setv (edge_handle, attr_name, attr_value); Set value of existing attribute of graph/node/edge (using attribute handle) string gv.setv (graph_handle, attr_handle, attr_value); string gv.setv (node_handle, attr_handle, attr_value); string gv.setv (edge_handle, attr_handle, attr_value); Getting attribute values Get value of named attribute of graph/node/edge string gv.getv (graph_handle, attr_name); string gv.getv (node_handle, attr_name); string gv.getv (edge_handle, attr_name); Get value of attribute of graph/node/edge (using attribute handle) string gv.getv (graph_handle, attr_handle); string gv.getv (node_handle, attr_handle); string gv.getv (edge_handle, attr_handle); Obtain names from handles string gv.nameof (graph_handle); string gv.nameof (node_handle); string gv.nameof (attr_handle); Find handles from names graph_handle gv.findsubg (graph_handle, name); node_handle gv.findnode (graph_handle, name); edge_handle gv.findedge (tail_node_handle, head_node_handle); attribute_handle gv.findattr (graph_handle, name); attribute_handle gv.findattr (node_handle, name); attribute_handle gv.findattr (edge_handle, name); Misc graph navigators returning handles node_handle gv.headof (edge_handle); node_handle gv.tailof (edge_handle); graph_handle gv.graphof (graph_handle); graph_handle gv.graphof (edge_handle); graph_handle gv.graphof (node_handle); graph_handle gv.rootof (graph_handle); Obtain handles of proto node/edge for setting default attribute values node_handle gv.protonode (graph_handle); edge_handle gv.protoedge (graph_handle); Iterators Iteration termination tests bool gv.ok (graph_handle); bool gv.ok (node_handle); bool gv.ok (edge_handle); bool gv.ok (attr_handle); Iterate over subgraphs of a graph graph_handle gv.firstsubg (graph_handle); graph_handle gv.nextsubg (graph_handle, subgraph_handle); Iterate over supergraphs of a graph (obscure and rarely useful) graph_handle gv.firstsupg (graph_handle); graph_handle gv.nextsupg (graph_handle, subgraph_handle); Iterate over edges of a graph edge_handle gv.firstedge (graph_handle); edge_handle gv.nextedge (graph_handle, edge_handle); Iterate over outedges of a graph edge_handle gv.firstout (graph_handle); edge_handle gv.nextout (graph_handle, edge_handle); Iterate over edges of a node edge_handle gv.firstedge (node_handle); edge_handle gv.nextedge (node_handle, edge_handle); Iterate over out-edges of a node edge_handle gv.firstout (node_handle); edge_handle gv.nextout (node_handle, edge_handle); Iterate over head nodes reachable from out-edges of a node node_handle gv.firsthead (node_handle); node_handle gv.nexthead (node_handle, head_node_handle); Iterate over in-edges of a graph edge_handle gv.firstin (graph_handle); edge_handle gv.nextin (node_handle, edge_handle); Iterate over in-edges of a node edge_handle gv.firstin (node_handle); edge_handle gv.nextin (graph_handle, edge_handle); Iterate over tail nodes reachable from in-edges of a node node_handle gv.firsttail (node_handle); node_handle gv.nexttail (node_handle, tail_node_handle); Iterate over nodes of a graph node_handle gv.firstnode (graph_handle); node_handle gv.nextnode (graph_handle, node_handle); Iterate over nodes of an edge node_handle gv.firstnode (edge_handle); node_handle gv.nextnode (edge_handle, node_handle); Iterate over attributes of a graph attribute_handle gv.firstattr (graph_handle); attribute_handle gv.nextattr (graph_handle, attr_handle); Iterate over attributes of an edge attribute_handle gv.firstattr (edge_handle); attribute_handle gv.nextattr (edge_handle, attr_handle); Iterate over attributes of a node attribute_handle gv.firstattr (node_handle); attribute_handle gv.nextattr (node_handle, attr_handle); Remove graph objects bool gv.rm (graph_handle); bool gv.rm (node_handle); bool gv.rm (edge_handle); Layout Annotate a graph with layout attributes and values using a specific layout engine bool gv.layout (graph_handle, string engine); Render Render a layout into attributes of the graph bool gv.render (graph_handle); Render a layout to stdout bool gv.render (graph_handle, string format); Render to an open file bool gv.render (graph_handle, string format, channel fout); Render a layout to an unopened file by name bool gv.render (graph_handle, string format, string filename); Render to a string result string gv.renderresult (graph_handle ing, string format); gv.renderresult (graph_handle, string format, string outdata); Render to an open channel bool gv.renderchannel (graph_handle, string format, string channelname); 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]" ) string gv.renderdata (graph_handle, string format); Writing graph back to file bool gv.write (graph_handle, string filename); bool gv.write (graph_handle, channel); Graph transformation tools bool gv.tred (graph_handle); KEYWORDS graph, dot, neato, fdp, circo, twopi, lua. 29 April 2024 gv(3lua)