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require 'torch'
local ffiOk = false
local graphvizOk = false
local cgraphOk = false
local ffi
local graphviz
local cgraph
ffiOk, ffi = pcall(require, 'ffi')
if ffiOk then
ffi.cdef[[
typedef struct FILE FILE;
typedef struct Agraph_s Agraph_t;
typedef struct Agnode_s Agnode_t;
extern Agraph_t *agmemread(const char *cp);
extern char *agget(void *obj, char *name);
extern int agclose(Agraph_t * g);
extern Agnode_t *agfstnode(Agraph_t * g);
extern Agnode_t *agnxtnode(Agraph_t * g, Agnode_t * n);
extern Agnode_t *aglstnode(Agraph_t * g);
extern Agnode_t *agprvnode(Agraph_t * g, Agnode_t * n);
typedef struct Agraph_s graph_t;
typedef struct GVJ_s GVJ_t;
typedef struct GVG_s GVG_t;
typedef struct GVC_s GVC_t;
extern GVC_t *gvContext(void);
extern int gvLayout(GVC_t *context, graph_t *g, const char *engine);
extern int gvRender(GVC_t *context, graph_t *g, const char *format, FILE *out);
extern int gvFreeLayout(GVC_t *context, graph_t *g);
extern int gvFreeContext(GVC_t *context);
]]
graphvizOk, graphviz = pcall(function() return ffi.load('libgvc') end)
cgraphOk, cgraph = pcall(function() return ffi.load('libcgraph') end)
else
graphvizOk = false
cgraphOk = false
end
-- Retrieve attribute data from a graphviz object.
local function getAttribute(obj, name)
local res = cgraph.agget(obj, ffi.cast("char*", name))
assert(res ~= ffi.cast("char*", nil), 'could not get attr ' .. name)
return ffi.string(res)
end
-- Iterate through nodes of a graphviz graph.
local function nodeIterator(graph)
local node = cgraph.agfstnode(graph)
local nextNode
return function()
if node == nil then return end
if node == cgraph.aglstnode(graph) then nextNode = nil end
nextNode = cgraph.agnxtnode(graph, node)
local result = node
node = nextNode
return result
end
end
-- Convert a string of comma-separated numbers to actual numbers.
local function extractNumbers(n, attr)
local res = {}
for number in string.gmatch(attr, "[^%,]+") do
table.insert(res, tonumber(number))
end
assert(#res == n, "attribute is not of expected form")
return unpack(res)
end
-- Transform from graphviz coordinates to unit square.
local function getRelativePosition(node, bbox)
local x0, y0, w, h = unpack(bbox)
local x, y = extractNumbers(2, getAttribute(node, 'pos'))
local xt = (x - x0) / w
local yt = (y - y0) / h
assert(xt >= 0 and xt <= 1, "bad x coordinate")
assert(yt >= 0 and yt <= 1, "bad y coordinate")
return xt, yt
end
-- Retrieve a node's ID based on its label string.
local function getID(node)
local label = getAttribute(node, 'label')
local res = {string.find(label, "^Node(%d+)")} or {string.find(label, "%((%d+)%)\\n")}
local id = res[3]
assert(id ~= nil, "could not get ID from node label : <" .. tostring(label) .. ">")
return tonumber(id)
end
--[[ Lay out a graph and return the positions of the nodes.
Args:
* `g` - graph to lay out.
* `algorithm` - name of the graphviz algorithm to use. (default: "dot")
Returns:
* `torch.Tensor(n, 2)` containing the resulting positions of the nodes.
where `n` is the number of nodes in the graph.
Coordinates are in the interval [0, 1].
]]
function graph.graphvizLayout(g, algorithm)
if not graphvizOk or not cgraphOk then
error("graphviz library could not be loaded.")
end
local nNodes = #g.nodes
local context = graphviz.gvContext()
local graphvizGraph = cgraph.agmemread(g:todot())
local algorithm = algorithm or "dot"
assert(0 == graphviz.gvLayout(context, graphvizGraph, algorithm),
"graphviz layout failed")
assert(0 == graphviz.gvRender(context, graphvizGraph, algorithm, nil),
"graphviz render failed")
-- Extract bounding box.
local x0, y0, x1, y1 = extractNumbers(4,
getAttribute(graphvizGraph, 'bb'), ",")
local w = x1 - x0
local h = y1 - y0
local bbox = { x0, y0, w, h }
-- Extract node positions.
local positions = torch.zeros(nNodes, 2)
for node in nodeIterator(graphvizGraph) do
local id = getID(node)
local x, y = getRelativePosition(node, bbox)
positions[id][1] = x
positions[id][2] = y
end
-- Clean up.
graphviz.gvFreeLayout(context, graphvizGraph)
cgraph.agclose(graphvizGraph)
graphviz.gvFreeContext(context)
return positions
end
function graph.graphvizFile(g, algorithm, fname)
algorithm = algorithm or 'dot'
local _,_,rendertype = fname:reverse():find('(%a+)%.%w+')
rendertype = rendertype:reverse()
local context = graphviz.gvContext()
local graphvizGraph = cgraph.agmemread(g:todot())
assert(0 == graphviz.gvLayout(context, graphvizGraph, algorithm),
"graphviz layout failed")
assert(0 == graphviz.gvRender(context, graphvizGraph, rendertype, io.open(fname, 'w')),
"graphviz render failed")
graphviz.gvFreeLayout(context, graphvizGraph)
cgraph.agclose(graphvizGraph)
graphviz.gvFreeContext(context)
end
--[[
Given a graph, dump an SVG or display it using graphviz.
Args:
* `g` - graph to display
* `title` - Title to display in the graph
* `fname` - [optional] if given it should contain a file name without an extension,
the graph is saved on disk as fname.svg and display is not shown. If not given
the graph is shown on qt display (you need to have qtsvg installed and running qlua)
Returns:
* `qs` - the window handle for the qt display (if fname given) or nil
]]
function graph.dot(g,title,fname)
local qt_display = fname == nil
fname = fname or os.tmpname()
local fnsvg = fname .. '.svg'
local fndot = fname .. '.dot'
graph.graphvizFile(g, 'dot', fnsvg)
graph.graphvizFile(g, 'dot', fndot)
if qt_display then
require 'qtsvg'
local qs = qt.QSvgWidget(fnsvg)
qs:show()
os.remove(fnsvg)
os.remove(fndot)
return qs
end
end
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