1 files changed, 45 insertions, 0 deletions
diff --git a/contrib/lua-torch/nn/Narrow.lua b/contrib/lua-torch/nn/Narrow.lua
new file mode 100644
index 000000000..a6ebaa321
--- /dev/null
+++ b/contrib/lua-torch/nn/Narrow.lua
@@ -0,0 +1,45 @@
+local Narrow, parent = torch.class('nn.Narrow', 'nn.Module')
+
+function Narrow:__init(dimension,offset,length)
+   parent.__init(self)
+   self.dimension=dimension
+   self.index=offset
+   self.length=length or 1
+   if not dimension or not offset then
+      error('nn.Narrow(dimension, offset, length)')
+   end
+end
+
+function Narrow:updateOutput(input)
+   local dim = self.dimension < 0 and input:dim() + self.dimension + 1 or self.dimension
+   local length = self.length
+   if length < 0 then
+      length = input:size(dim) - self.index + self.length + 2
+   end
+   local index = self.index
+   if self.index < 0 then
+      index = 1
+      length = input:size(dim) - length
+   end
+   local output=input:narrow(dim, index, length)
+   self.output = self.output:typeAs(output)
+   self.output:resizeAs(output):copy(output)
+   return self.output
+end
+
+function Narrow:updateGradInput(input, gradOutput)
+   local dim = self.dimension < 0 and input:dim() + self.dimension + 1 or self.dimension
+   local length = self.length
+   if length < 0 then
+      length = input:size(dim) - self.index + self.length + 2
+   end
+   local index = self.index
+   if self.index < 0 then
+      index = 1
+      length = input:size(dim) - length
+   end
+   self.gradInput = self.gradInput:typeAs(input)
+   self.gradInput:resizeAs(input):zero()
+   self.gradInput:narrow(dim,index,length):copy(gradOutput)
+   return self.gradInput
+end