TransformerDecoderLayer

class torch.nn.TransformerDecoderLayer(d_model, nhead, dim_feedforward=2048, dropout=0.1, activation=<function relu>, layer_norm_eps=1e-05, batch_first=False, norm_first=False, device=None, dtype=None)

TransformerDecoderLayer is made up of self-attn, multi-head-attn and feedforward network. This standard decoder layer is based on the paper “Attention Is All You Need”. Ashish Vaswani, Noam Shazeer, Niki Parmar, Jakob Uszkoreit, Llion Jones, Aidan N Gomez, Lukasz Kaiser, and Illia Polosukhin. 2017. Attention is all you need. In Advances in Neural Information Processing Systems, pages 6000-6010. Users may modify or implement in a different way during application.

Parameters

• d_model – the number of expected features in the input (required).

• nhead – the number of heads in the multiheadattention models (required).

• dim_feedforward – the dimension of the feedforward network model (default=2048).

• dropout – the dropout value (default=0.1).

• activation – the activation function of the intermediate layer, can be a string (“relu” or “gelu”) or a unary callable. Default: relu

• layer_norm_eps – the eps value in layer normalization components (default=1e-5).

• batch_first – If True, then the input and output tensors are provided as (batch, seq, feature). Default: False.

• norm_first – if True, layer norm is done prior to self attention, multihead attention and feedforward operations, respectivaly. Otherwise it’s done after. Default: False (after).

Examples::

>>> decoder_layer = nn.TransformerDecoderLayer(d_model=512, nhead=8)
>>> memory = torch.rand(10, 32, 512)
>>> tgt = torch.rand(20, 32, 512)
>>> out = decoder_layer(tgt, memory)

Alternatively, when batch_first is True:

>>> decoder_layer = nn.TransformerDecoderLayer(d_model=512, nhead=8, batch_first=True)
>>> memory = torch.rand(32, 10, 512)
>>> tgt = torch.rand(32, 20, 512)
>>> out = decoder_layer(tgt, memory)

forward(tgt, memory, tgt_mask=None, memory_mask=None, tgt_key_padding_mask=None, memory_key_padding_mask=None)

Pass the inputs (and mask) through the decoder layer.

Parameters

• tgt – the sequence to the decoder layer (required).

• memory – the sequence from the last layer of the encoder (required).

• tgt_mask – the mask for the tgt sequence (optional).

• memory_mask – the mask for the memory sequence (optional).

• tgt_key_padding_mask – the mask for the tgt keys per batch (optional).

• memory_key_padding_mask – the mask for the memory keys per batch (optional).

Shape:

see the docs in Transformer class.