X-Git-Url: https://fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;f=dagnn.lua;h=1b467e720542469d45228b1dbc8a8fd0b021f6ad;hb=e5030cca047eed4b8c5db172fc52e893b1b1d843;hp=52913ad9992f404277a9b695be590baaa9cdedea;hpb=be03a73e411d18082a2dd99bff5df45c085017ca;p=dagnn.git

diff --git a/dagnn.lua b/dagnn.lua
index 52913ad..1b467e7 100755
--- a/dagnn.lua
+++ b/dagnn.lua
@@ -11,6 +11,7 @@ function DAG:__init()
 end
 
 function DAG:addEdge(a, b)
+   self.sorted = nil
    local pred, succ = self.pred, self.succ
    if not pred[a] and not succ[a] then
       self:add(a)
@@ -24,38 +25,62 @@ function DAG:addEdge(a, b)
    succ[a][#succ[a] + 1] = b
 end
 
-function DAG:setInput(i)
-   if torch.type(i) == 'table' then
-      self.inputModules = i
-      for _, m in ipairs(i) do
-         if not self.pred[m] and not self.succ[m] then
-            self:add(m)
-         end
+-- Apply f on t recursively; use the corresponding a1 and a2 elements
+-- (i.e. same keys) as second and third parameters to f when
+-- available; return the results from f, organized in a similarly
+-- nested table.
+function DAG:applyOnModules(f, t, a1, a2)
+   if torch.type(t) == 'table' then
+      local result = {}
+      for k, s in pairs(t) do
+         result[k] = self:applyOnModules(f, s, a1 and a1[k], a2 and a2[k])
       end
+      return result
    else
-      self:setInput({ i })
+      return f(t, a1, a2)
    end
 end
 
+function DAG:setInput(i)
+   self.sorted = nil
+   self.inputModules = i
+   self:applyOnModules(
+      function(m)
+         if not self.succ[m] or #self.succ[m] == 0 then
+            error('Input modules must have outgoing  edges.')
+         end
+         if self.pred[m] and #self.pred[m] > 0 then
+            error('Input modules cannog have incoming edges.')
+         end
+      end,
+      self.inputModules
+   )
+end
+
 function DAG:setOutput(o)
-   if torch.type(o) == 'table' then
-      self.outputModules = o
-      for _, m in ipairs(o) do
-         if not self.pred[m] and not self.succ[m] then
-            self:add(m)
+   self.sorted = nil
+   self.outputModules = o
+   self:applyOnModules(
+      function(m)
+         if not self.pred[m] or #self.pred[m] == 0 then
+            error('Output module must have incoming edges.')
          end
-      end
-   else
-      self:setOutput({ o })
-   end
+         if self.succ[m] and #self.succ[m] > 0 then
+            error('Output module cannot have outgoing edges.')
+         end
+      end,
+      self.outputModules
+   )
 end
 
-function DAG:order()
+function DAG:sort()
+   if self.sorted then
+      return
+   end
+
    local distance = {}
 
-   for _, a in pairs(self.inputModules) do
-      distance[a] = 1
-   end
+   self:applyOnModules(function(m) distance[m] = 1 end, self.inputModules)
 
    local nc
 
@@ -81,19 +106,17 @@ function DAG:order()
 end
 
 function DAG:print()
+   self:sort()
+
    for i, d in ipairs(self.sorted) do
       print('#' .. i .. ' -> ' .. torch.type(d))
    end
 end
 
 function DAG:updateOutput(input)
-   if #self.inputModules == 1 then
-      self.inputModules[1]:updateOutput(input)
-   else
-      for i, d in ipairs(self.inputModules) do
-         d:updateOutput(input[i])
-      end
-   end
+   self:sort()
+
+   self:applyOnModules(function(m, i) m:updateOutput(i) end, self.inputModules, input)
 
    for _, d in ipairs(self.sorted) do
       if self.pred[d] then
@@ -109,14 +132,41 @@ function DAG:updateOutput(input)
       end
    end
 
-   if #self.outputModules == 1 then
-      self.output = self.outputModules[1].output
-   else
-      self.output = { }
-      for i, d in ipairs(self.outputModules) do
-         self.output[i] = d.output
+   self.output = self:applyOnModules(function(m) return m.output end, self.outputModules)
+
+   return self.output
+end
+
+function DAG:updateGradInput(input, gradOutput)
+   self:sort()
+
+   self:applyOnModules(
+      function(m, i, go) m:updateGradInput(i, go) end,
+      self.outputModules, input, gradOutput
+   )
+
+   for k = self.sorted, 1, -1 do
+      local m = sorted[k]
+      if self.succ[d] then
+         if #self.succ[d] == 1 then
+            d:updateGradInput(self.succ[d][1].gradInput)
+         elseif #self.succ[d] > 1 then
+            local sum
+            for k = 1, #self.succ[d] do
+               if sum then
+                  sum:add(self.succ[d][k].gradInput)
+               else
+                  sum = self.succ[d][k].gradInput:clone()
+               end
+            end
+            d:updateGradInput(sum)
+         end
       end
    end
 
-   return self.output
+   self.gradInput = self:applyOnModules(function(m) return m.gradInput end, self.inputModules)
+
+   return self.gradInput
 end
+
+return DAG