From 14a2e4cdcb64af8452feb163455446143b42ccf2 Mon Sep 17 00:00:00 2001
From: koray kavukcuoglu <koray@kavukcuoglu.org>
Date: Wed, 3 Apr 2013 22:07:50 +0100
Subject: [PATCH] add 'id' field to Node correct reverse/clone/topsort
 functions

---
 Node.lua  |  1 +
 init.lua  | 65 ++++++++++++++++++++++++++++++++++++++++---------------
 utils.lua |  4 ++--
 3 files changed, 50 insertions(+), 20 deletions(-)

diff --git a/Node.lua b/Node.lua
index 84c52a5..459f9a8 100644
--- a/Node.lua
+++ b/Node.lua
@@ -13,6 +13,7 @@ local Node = torch.class('graph.Node')
 
 function Node:__init(d,p)
 	self.data = d
+	self.id = 0
 	self.children = {}
 	self.visited = false
 	self.marked = false
diff --git a/init.lua b/init.lua
index 9bc15c6..737bca9 100644
--- a/init.lua
+++ b/init.lua
@@ -43,6 +43,8 @@ function Graph:add(edge)
 		end
 		-- add the edge to the node for parsing in nodes
 		edge.from:add(edge.to)
+		edge.from.id = self.nodes[edge.from]
+		edge.to.id = self.nodes[edge.to]
 	else
 		for i,e in ipairs(edge) do
 			self:add(e)
@@ -55,15 +57,18 @@ end
 -- Note that primitive data types like numbers can not be shared
 function Graph:clone()
 	local clone = graph.Graph()
+	local nodes = {}
+	for i,n in ipairs(self.nodes) do
+		table.insert(nodes,n.new(n.data))
+	end
 	for i,e in ipairs(self.edges) do
-		local from = graph.Node(e.from.data)
-		local to   = graph.Node(e.to.data)
-		clone:add(graph.Edge(from,to))
+		local from = nodes[self.nodes[e.from]]
+		local to   = nodes[self.nodes[e.to]]
+		clone:add(e.new(from,to))
 	end
 	return clone
 end
 
-
 -- It returns a new graph where the edges are reversed.
 -- The nodes share the data. Note that primitive data types can
 -- not be shared.
@@ -75,25 +80,23 @@ function Graph:reverse()
 		mapnodes[e.to]   = mapnodes[e.to] or e.to.new(e.to.data)
 		local from = mapnodes[e.from]
 		local to   = mapnodes[e.to]
-		rg:add(graph.Edge(to,from))
+		rg:add(e.new(to,from))
 	end
-	return rg
+	return rg,mapnodes
 end
 
 --[[
 	Topological Sort
+	** This is not finished. OK for graphs with single root.
 ]]--
 function Graph:topsort()
-	-- first clone the graph
-	local g = self:clone()
-	local nodes = g.nodes
-	local edges = g.edges
-	for i,node in ipairs(nodes) do
-		node.children = {}
-	end
 
 	-- reverse the graph
-	local rg = self:reverse()
+	local rg,map = self:reverse()
+	local rmap = {}
+	for k,v in pairs(map) do
+		rmap[v] = k
+	end
 
 	-- work on the sorted graph
 	local sortednodes = {}
@@ -105,7 +108,7 @@ function Graph:topsort()
 
 	-- run
 	for i,root in ipairs(rootnodes) do
-		root:dfs(function(node) table.insert(sortednodes,node) end)
+		root:dfs(function(node) table.insert(sortednodes,rmap[node]) end)
 	end
 
 	if #sortednodes ~= #self.nodes then
@@ -137,16 +140,42 @@ function Graph:roots()
 	return roots
 end
 
-function Graph:todot()
+-- find root nodes
+function Graph:leaves()
+	local edges = self.edges
+	local leafnodes = {}
+	for i,edge in ipairs(edges) do
+		--table.insert(rootnodes,edge.from)
+		if not leafnodes[edge.to] then
+			leafnodes[edge.to] = #leafnodes+1
+		end
+	end
+	for i,edge in ipairs(edges) do
+		if leafnodes[edge.from] then
+			leafnodes[edge.from] = nil
+		end
+	end
+	local leaves = {}
+	for leaf,i in pairs(leafnodes) do
+		table.insert(leaves, leaf)
+	end
+	table.sort(leaves,function(a,b) return self.nodes[a] < self.nodes[b] end )
+	return leaves
+end
+
+function Graph:todot(title)
 	local nodes = self.nodes
 	local edges = self.edges
 	str = {}
 	table.insert(str,'digraph G {\n')
+	if title then
+		table.insert(str,'labelloc="t";\nlabel="' .. title .. '";\n')
+	end
 	table.insert(str,'node [shape = oval]; ')
 	local nodelabels = {}
 	for i,node in ipairs(nodes) do
-		local l =  '"' .. (node:label() or 'n' .. i) .. '"'
-		nodelabels[node] = 'n' .. i
+		local l =  '"' .. ( 'Node' .. node.id .. '\\n' .. node:label() ) .. '"'
+		nodelabels[node] = 'n' .. node.id
 		table.insert(str, '\n' .. nodelabels[node] .. '[label=' .. l .. '];')
 	end
 	table.insert(str,'\n')
diff --git a/utils.lua b/utils.lua
index f4ba52b..22600c8 100644
--- a/utils.lua
+++ b/utils.lua
@@ -1,8 +1,8 @@
 
 require 'qtsvg'
 
-function graph.dot(g,fname)
-	local gv = g:todot()
+function graph.dot(g,title,fname)
+	local gv = g:todot(title)
 	local fngv = (fname or os.tmpname()) .. '.dot'
 	local fgv = io.open(fngv,'w')
 	fgv:write(gv)