Element-Research / rnn

Recurrent Neural Network library for Torch7's nn
BSD 3-Clause "New" or "Revised" License
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How to use this library to implement recurrent module whose input of at time step t is the output of the time step t-1? #377

Open squidszyd opened 7 years ago

squidszyd commented 7 years ago

I'm currently working on a recurrent network which process the input, which is the output of the last step, and output result to be used at the next step. And, at every step, there is a loss to compute. But, using nn.Sequencer will wrap these time steps into one forward step and I haven't figured out how to link the input[t] with output[t-1]. I'm now using nn.Recurrent() to implement this but I don't know if it is right. The code looks like this: --Model-- r = nn.Recurrent(..., ..., nn.FastLSTM(..., ...), nStep) net = nn.Sequential():add(r):add(... some output module ...) -- Forward -- for s = 1, nStep do o[s] = net:forward(o[s-1]) end -- BPTT-- for s = nStep, 1, -1 do ... -- gradOutput of this step is the sum of gradInput from next step and grad from criterion of this step gradOutput[s] = criterion:backward(o[s], target[s]) + gradInput[s + 1] gradInput[s] = network:backward(o[s-1], gradOutput[s]) ...

I'm wondering if my code is suitable for implementing my need or if I have missed something here?

And here is another question: Is it possible to use this library to implement a recurrent module that receive different size of input when t=1? E.g. when t = 1, the input is a 2 x 10 tensor and when t>1, the inputs are 2 x 12 tensors.