Problem running GRU model; missing argument for forward() - pytorch

Question

I am working on a GRU and when I try to make predictions I get an error indicating that I need to define h for forward(). I have tried several things and ran out of patience after googling and scouring stack overflow for hours.
This is the class:
class GRUNet(nn.Module):
def __init__(self, input_dim, hidden_dim, output_dim, n_layers, drop_prob = 0.2):
super(GRUNet, self).__init__()
self.hidden_dim = hidden_dim
self.n_layers = n_layers
self.gru = nn.GRU(input_dim, hidden_dim, n_layers, batch_first=True, dropout=drop_prob)
self.fc = nn.Linear(hidden_dim, output_dim)
self.relu = nn.ReLU()
def forward(self, x, h):
out, h = self.gru(x,h)
out = self.fc(self.relu(out[:,-1]))
return out, h
def init_hidden(self, batch_size):
weight = next(self.parameters()).data
hidden = weight.new(self.n_layers, batch_size, self.hidden_dim).zero_().to(device)
return hidden
and then this is where I load the model and try to make a prediction. Both of these are in the same script.
inputs = np.load('.//Pred//input_list.npy')
print(inputs.ndim, inputs.shape)
Gmodel = GRUNet(24,256,1,2)
Gmodel = torch.load('.//GRU//GRU_1028_48.pkl')
Gmodel.eval()
pred = Gmodel(inputs)
Without any other arguments to Gmodel I get the following:
Traceback (most recent call last):
File ".\grunet.py", line 136, in <module>
pred = Gmodel(inputs)
File "C:\Users\ryang\Anaconda-3\envs\tf-gpu\lib\site-packages\torch\nn\modules\module.py", line 547, in __call__
result = self.forward(*input, **kwargs)
TypeError: forward() missing 1 required positional argument: 'h'

Answer 1

You need to provide the hidden state as well which is usually initially all zeros or simply None!
That is you either need to explicitly provide one like this :
hidden_state = torch.zeros(size=(num_layers*direction, batch_size, hidden_dim)).to(device)
pred = Gmodel(inputs, hidden_state)
or simply do :
hidden_state = None
pred = Gmodel(inputs, hidden_state)