gv(3python)															       gv(3python)

NAME

       gv_python - graph manipulation in python

SYNOPSIS

       #!/usr/bin/python
       import gv

USAGE

INTRODUCTION

       gv_python is a dynamically loaded extension for python 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 an open channel
	      bool gv.renderchannel (graph_handle, string format, string channelname);

       Render to a string result
	      gv.renderresult (graph_handle, string format, string outdata);

       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);

KEYWORDS

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

								  11 January 2014						       gv(3python)