Today, when I using PyTorch to build a LSTM model, I got an error occured:
LSTM RuntimeError: input must have 3 dimensions, got 2This is unexpected for me. I use this model structure again, but the last time I didn’t get the error message. But I print the input tensor size, I finally understood what was wrong.
My input tensor dimension is mismatch.
The input dimension need to be (batch_size, seq_len, input_size). But my data just have (batch_size, input_size).
After adjustment, it can run normally.
It should be noted that PyTorch’s nn.LSTM () has a parameter of “batch_first”. If True, the input format “batch_size” is the first one. If “batch_first” is False, the “batch_size” and “seq_len” positions are swapped.