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modeling_perceiver.py
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modeling_perceiver.py
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# coding=utf-8
# Copyright 2021 Deepmind and The HuggingFace Inc. team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
""" PyTorch Perceiver model."""
import abc
import math
from dataclasses import dataclass
from functools import reduce
from operator import __add__
from typing import Any, Callable, Dict, List, Mapping, Optional, Tuple, Union
import numpy as np
import torch
import torch.utils.checkpoint
from torch import nn
from torch.nn import BCEWithLogitsLoss, CrossEntropyLoss, MSELoss
from ...activations import ACT2FN
from ...modeling_outputs import BaseModelOutputWithCrossAttentions
from ...modeling_utils import PreTrainedModel
from ...pytorch_utils import apply_chunking_to_forward, find_pruneable_heads_and_indices, meshgrid, prune_linear_layer
from ...utils import (
ModelOutput,
add_start_docstrings,
add_start_docstrings_to_model_forward,
logging,
replace_return_docstrings,
)
from .configuration_perceiver import PerceiverConfig
ModalitySizeType = Mapping[str, int]
PreprocessorOutputType = Tuple[torch.Tensor, Optional[torch.Tensor], torch.Tensor]
PreprocessorType = Callable[..., PreprocessorOutputType]
PostprocessorType = Callable[..., Any]
logger = logging.get_logger(__name__)
_CHECKPOINT_FOR_DOC = "deepmind/language-perceiver"
_CONFIG_FOR_DOC = "PerceiverConfig"
PERCEIVER_PRETRAINED_MODEL_ARCHIVE_LIST = [
"deepmind/language-perceiver",
# See all Perceiver models at https://huggingface.co/models?filter=perceiver
]
@dataclass
class PerceiverModelOutput(ModelOutput):
"""
Base class for Perceiver base model's outputs, with potential hidden states, attentions and cross-attentions.
Args:
logits (`torch.FloatTensor` of shape `(batch_size, num_labels)`):
Classification (or regression if config.num_labels==1) scores (before SoftMax).
last_hidden_state (`torch.FloatTensor` of shape `(batch_size, sequence_length, hidden_size)`):
Sequence of hidden-states at the output of the last layer of the model.
hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `torch.FloatTensor` (one for the output of the embeddings + one for the output of each layer) of
shape `(batch_size, sequence_length, hidden_size)`. Hidden-states of the model at the output of each layer
plus the initial embedding outputs.
attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `torch.FloatTensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
sequence_length)`. Attentions weights after the attention softmax, used to compute the weighted average in
the self-attention heads.
cross_attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `torch.FloatTensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
sequence_length)`. Attentions weights of the decoder's cross-attention layer, after the attention softmax,
used to compute the weighted average in the cross-attention heads.
"""
logits: torch.FloatTensor = None
last_hidden_state: torch.FloatTensor = None
hidden_states: Optional[Tuple[torch.FloatTensor]] = None
attentions: Optional[Tuple[torch.FloatTensor]] = None
cross_attentions: Optional[Tuple[torch.FloatTensor]] = None
@dataclass
class PerceiverDecoderOutput(ModelOutput):
"""
Base class for Perceiver decoder outputs, with potential cross-attentions.
Args:
logits (`torch.FloatTensor` of shape `(batch_size, num_labels)`):
Output of the basic decoder.
cross_attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `torch.FloatTensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
sequence_length)`. Attentions weights of the decoder's cross-attention layer, after the attention softmax,
used to compute the weighted average in the cross-attention heads.
"""
logits: torch.FloatTensor = None
cross_attentions: Optional[Tuple[torch.FloatTensor]] = None
@dataclass
class PerceiverMaskedLMOutput(ModelOutput):
"""
Base class for Perceiver's masked language model outputs.
Args:
loss (`torch.FloatTensor` of shape `(1,)`, *optional*, returned when `labels` is provided):
Masked language modeling (MLM) loss.
logits (`torch.FloatTensor` of shape `(batch_size, sequence_length, config.vocab_size)`):
Prediction scores of the language modeling head (scores for each vocabulary token before SoftMax).
hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `torch.FloatTensor` (one for the output of the embeddings + one for the output of each layer) of
shape `(batch_size, sequence_length, hidden_size)`. Hidden-states of the model at the output of each layer
plus the initial embedding outputs.
attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `torch.FloatTensor` (one for each layer) of shape `(batch_size, num_heads, num_latents,
num_latents)`. Attentions weights after the attention softmax, used to compute the weighted average in the
self-attention heads.
cross_attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `torch.FloatTensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
sequence_length)`. Attentions weights of the decoder's cross-attention layer, after the attention softmax,
used to compute the weighted average in the cross-attention heads.
"""
loss: Optional[torch.FloatTensor] = None
logits: torch.FloatTensor = None
hidden_states: Optional[Tuple[torch.FloatTensor]] = None
attentions: Optional[Tuple[torch.FloatTensor]] = None
cross_attentions: Optional[Tuple[torch.FloatTensor]] = None
@dataclass
class PerceiverClassifierOutput(ModelOutput):
"""
Base class for Perceiver's outputs of sequence/image classification models, optical flow and multimodal
autoencoding.
Args:
loss (`torch.FloatTensor` of shape `(1,)`, *optional*, returned when `labels` is provided):
Classification (or regression if config.num_labels==1) loss.
logits (`torch.FloatTensor` of shape `(batch_size, config.num_labels)`):
Classification (or regression if config.num_labels==1) scores (before SoftMax).
hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
Tuple of `torch.FloatTensor` (one for the output of the embeddings + one for the output of each layer) of
shape `(batch_size, sequence_length, hidden_size)`. Hidden-states of the model at the output of each layer
plus the initial embedding outputs.
attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `torch.FloatTensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
sequence_length)`. Attentions weights after the attention softmax, used to compute the weighted average in
the self-attention heads.
cross_attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`):
Tuple of `torch.FloatTensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length,
sequence_length)`. Attentions weights of the decoder's cross-attention layer, after the attention softmax,
used to compute the weighted average in the cross-attention heads.
"""
loss: Optional[torch.FloatTensor] = None
logits: torch.FloatTensor = None
hidden_states: Optional[Tuple[torch.FloatTensor]] = None
attentions: Optional[Tuple[torch.FloatTensor]] = None
cross_attentions: Optional[Tuple[torch.FloatTensor]] = None
class PerceiverEmbeddings(nn.Module):
"""Construct the latent embeddings."""
def __init__(self, config):
super().__init__()
self.latents = nn.Parameter(torch.randn(config.num_latents, config.d_latents))
def forward(self, batch_size: int):
return self.latents.expand(batch_size, -1, -1) # Thanks, Phil Wang
class PerceiverSelfAttention(nn.Module):
"""Multi-headed {cross, self}-attention. Can be used both in the encoder as well as in the decoder."""
def __init__(
self,
config,
is_cross_attention=False,
qk_channels=None,
v_channels=None,
num_heads=1,
q_dim=None,
kv_dim=None,
):
super().__init__()
self.num_heads = num_heads
# Q and K must have the same number of channels.
# Default to preserving Q's input's shape.
if qk_channels is None:
qk_channels = q_dim
# V's num_channels determines the shape of the output of QKV-attention.
# Default to the same number of channels used in the key-query operation.
if v_channels is None:
v_channels = qk_channels
if qk_channels % num_heads != 0:
raise ValueError(f"qk_channels ({qk_channels}) must be divisible by num_heads ({num_heads}).")
if v_channels % num_heads != 0:
raise ValueError(f"v_channels ({v_channels}) must be divisible by num_heads ({num_heads}).")
self.qk_channels = qk_channels
self.v_channels = v_channels
self.qk_channels_per_head = self.qk_channels // num_heads
self.v_channels_per_head = self.v_channels // num_heads
# Layer normalization
self.layernorm1 = nn.LayerNorm(q_dim)
self.layernorm2 = nn.LayerNorm(kv_dim) if is_cross_attention else nn.Identity()
# Projection matrices
self.query = nn.Linear(q_dim, qk_channels)
self.key = nn.Linear(kv_dim, qk_channels)
self.value = nn.Linear(kv_dim, v_channels)
self.dropout = nn.Dropout(config.attention_probs_dropout_prob)
def transpose_for_scores(self, x, channels_per_head):
new_x_shape = x.size()[:-1] + (self.num_heads, channels_per_head)
x = x.view(*new_x_shape)
return x.permute(0, 2, 1, 3)
def forward(
self,
hidden_states: torch.Tensor,
attention_mask: Optional[torch.FloatTensor] = None,
head_mask: Optional[torch.FloatTensor] = None,
inputs: Optional[torch.FloatTensor] = None,
inputs_mask: Optional[torch.FloatTensor] = None,
output_attentions: Optional[bool] = False,
) -> Tuple[torch.Tensor]:
hidden_states = self.layernorm1(hidden_states)
inputs = self.layernorm2(inputs)
# Project queries, keys and values to a common feature dimension. If this is instantiated as a cross-attention module,
# the keys and values come from the inputs; the attention mask needs to be such that the inputs's non-relevant tokens are not attended to.
is_cross_attention = inputs is not None
queries = self.query(hidden_states)
if is_cross_attention:
keys = self.key(inputs)
values = self.value(inputs)
attention_mask = inputs_mask
else:
keys = self.key(hidden_states)
values = self.value(hidden_states)
# Reshape channels for multi-head attention.
# We reshape from (batch_size, time, channels) to (batch_size, num_heads, time, channels per head)
queries = self.transpose_for_scores(queries, self.qk_channels_per_head)
keys = self.transpose_for_scores(keys, self.qk_channels_per_head)
values = self.transpose_for_scores(values, self.v_channels_per_head)
# Take the dot product between the queries and keys to get the raw attention scores.
attention_scores = torch.matmul(queries, keys.transpose(-1, -2))
batch_size, num_heads, seq_len, q_head_dim = queries.shape
_, _, _, v_head_dim = values.shape
hiddens = self.num_heads * v_head_dim
attention_scores = attention_scores / math.sqrt(q_head_dim)
if attention_mask is not None:
# Apply the attention mask (precomputed for all layers in PerceiverModel forward() function)
attention_scores = attention_scores + attention_mask
# Normalize the attention scores to probabilities.
attention_probs = nn.Softmax(dim=-1)(attention_scores)
# This is actually dropping out entire tokens to attend to, which might
# seem a bit unusual, but is taken from the original Transformer paper.
attention_probs = self.dropout(attention_probs)
# Mask heads if we want to
if head_mask is not None:
attention_probs = attention_probs * head_mask
context_layer = torch.matmul(attention_probs, values)
context_layer = context_layer.permute(0, 2, 1, 3).contiguous()
new_context_layer_shape = context_layer.size()[:-2] + (hiddens,)
context_layer = context_layer.view(*new_context_layer_shape)
outputs = (context_layer, attention_probs) if output_attentions else (context_layer,)
return outputs
class PerceiverSelfOutput(nn.Module):
def __init__(self, config, input_channels, output_channels):
super().__init__()
self.dense = nn.Linear(input_channels, output_channels)
def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
hidden_states = self.dense(hidden_states)
return hidden_states
class PerceiverAttention(nn.Module):
"""Attention module, including a dense block."""
def __init__(
self,
config,
is_cross_attention=False,
qk_channels=None,
v_channels=None,
num_heads=1,
q_dim=None,
kv_dim=None,
use_query_residual=True,
):
super().__init__()
# MultiHead attention
if is_cross_attention and qk_channels is None:
if config.cross_attention_shape_for_attention == "q":
qk_channels = q_dim
elif config.cross_attention_shape_for_attention == "kv":
qk_channels = kv_dim
else:
raise ValueError(
f"Unknown value {config.cross_attention_shape_for_attention} for "
"cross_attention_shape_for_attention."
)
else:
if qk_channels is None:
qk_channels = q_dim
if v_channels is None:
v_channels = qk_channels
self.self = PerceiverSelfAttention(
config,
is_cross_attention=is_cross_attention,
qk_channels=qk_channels,
v_channels=v_channels,
num_heads=num_heads,
q_dim=q_dim,
kv_dim=kv_dim,
)
# dense block
output_channels = None
if is_cross_attention:
output_channels = q_dim
else:
if output_channels is None:
output_channels = v_channels
self.output = PerceiverSelfOutput(config, input_channels=self.self.v_channels, output_channels=output_channels)
self.use_query_residual = use_query_residual
self.pruned_heads = set()
def prune_heads(self, heads):
if len(heads) == 0:
return
heads, index = find_pruneable_heads_and_indices(
heads, self.self.num_attention_heads, self.self.attention_head_size, self.pruned_heads
)
# Prune linear layers
self.self.query = prune_linear_layer(self.self.query, index)
self.self.key = prune_linear_layer(self.self.key, index)
self.self.value = prune_linear_layer(self.self.value, index)
self.output.dense = prune_linear_layer(self.output.dense, index, dim=1)
# Update hyper params and store pruned heads
self.self.num_attention_heads = self.self.num_attention_heads - len(heads)
self.self.all_head_size = self.self.attention_head_size * self.self.num_attention_heads
self.pruned_heads = self.pruned_heads.union(heads)
def forward(
self,
hidden_states: torch.Tensor,
attention_mask: Optional[torch.FloatTensor] = None,
head_mask: Optional[torch.FloatTensor] = None,
inputs: Optional[torch.FloatTensor] = None,
inputs_mask: Optional[torch.FloatTensor] = None,
output_attentions: Optional[bool] = False,
) -> Tuple[torch.Tensor]:
self_outputs = self.self(
hidden_states,
attention_mask,
head_mask,
inputs,
inputs_mask,
output_attentions,
)
# Output projection
attention_output = self.output(self_outputs[0])
# Optionally include a residual to the original queries.
# Consider omitting the residual if the semantics of query and output
# are different, e.g. if queries are positions and outputs are pixels.
if self.use_query_residual:
attention_output = attention_output + hidden_states
outputs = (attention_output,) + self_outputs[1:] # add attentions if we output them
return outputs
class PerceiverMLP(nn.Module):
"""A Transformer-style dense module to follow attention."""
def __init__(self, config, input_size, widening_factor):
super().__init__()
self.dense1 = nn.Linear(input_size, widening_factor * input_size)
if isinstance(config.hidden_act, str):
self.intermediate_act_fn = ACT2FN[config.hidden_act]
else:
self.intermediate_act_fn = config.hidden_act
self.dense2 = nn.Linear(widening_factor * input_size, input_size)
def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
hidden_states = self.dense1(hidden_states)
hidden_states = self.intermediate_act_fn(hidden_states)
hidden_states = self.dense2(hidden_states)
return hidden_states
class PerceiverLayer(nn.Module):
def __init__(
self,
config,
is_cross_attention=False,
qk_channels=None,
v_channels=None,
num_heads=1,
q_dim=None,
kv_dim=None,
widening_factor=4,
use_query_residual=True,
):
super().__init__()
self.chunk_size_feed_forward = config.chunk_size_feed_forward
self.seq_len_dim = 1
self.attention = PerceiverAttention(
config,
is_cross_attention=is_cross_attention,
qk_channels=qk_channels,
v_channels=v_channels,
num_heads=num_heads,
q_dim=q_dim,
kv_dim=kv_dim,
use_query_residual=use_query_residual,
)
self.layernorm = nn.LayerNorm(q_dim)
self.mlp = PerceiverMLP(config, input_size=q_dim, widening_factor=widening_factor)
def forward(
self,
hidden_states: torch.Tensor,
attention_mask: Optional[torch.FloatTensor] = None,
head_mask: Optional[torch.FloatTensor] = None,
inputs: Optional[torch.FloatTensor] = None,
inputs_mask: Optional[torch.FloatTensor] = None,
output_attentions: Optional[bool] = False,
) -> Tuple[torch.Tensor]:
attention_outputs = self.attention(
hidden_states,
attention_mask,
head_mask,
inputs,
inputs_mask,
output_attentions,
)
attention_output = attention_outputs[0]
outputs = attention_outputs[1:] # add attentions if we output attention weights
layer_output = apply_chunking_to_forward(
self.feed_forward_chunk, self.chunk_size_feed_forward, self.seq_len_dim, attention_output
)
layer_output = layer_output + attention_output # residual connection
outputs = (layer_output,) + outputs
return outputs
def feed_forward_chunk(self, attention_output):
layer_output = self.layernorm(attention_output)
layer_output = self.mlp(layer_output)
return layer_output
class PerceiverEncoder(nn.Module):
"""The Perceiver Encoder: a scalable, fully attentional encoder."""
def __init__(self, config, kv_dim=None):
super().__init__()
self.config = config
# Check that we can use multihead-attention with these shapes.
if config.d_latents % config.num_self_attention_heads != 0:
raise ValueError(
f"num_z_channels ({config.d_latents}) must be divisible by"
f" num_self_attend_heads ({config.num_self_attention_heads})."
)
if config.d_latents % config.num_cross_attention_heads != 0:
raise ValueError(
f"num_z_channels ({config.d_latents}) must be divisible by"
f" num_cross_attend_heads ({config.num_cross_attention_heads})."
)
# Construct the cross attention layer.
self.cross_attention = PerceiverLayer(
config,
is_cross_attention=True,
qk_channels=config.qk_channels,
v_channels=config.v_channels,
num_heads=config.num_cross_attention_heads,
q_dim=config.d_latents,
kv_dim=kv_dim,
widening_factor=config.cross_attention_widening_factor,
use_query_residual=config.use_query_residual,
)
# Construct a single block of self-attention layers.
# We get deeper architectures by applying this block more than once.
self_attention_layers = []
for _ in range(config.num_self_attends_per_block):
layer = PerceiverLayer(
config,
is_cross_attention=False,
qk_channels=config.qk_channels,
v_channels=config.v_channels,
num_heads=config.num_self_attention_heads,
q_dim=config.d_latents,
kv_dim=config.d_latents,
widening_factor=config.self_attention_widening_factor,
)
self_attention_layers.append(layer)
self.self_attends = nn.ModuleList(self_attention_layers)
def forward(
self,
hidden_states: torch.Tensor,
attention_mask: Optional[torch.FloatTensor] = None,
head_mask: Optional[torch.FloatTensor] = None,
inputs: Optional[torch.FloatTensor] = None,
inputs_mask: Optional[torch.FloatTensor] = None,
output_attentions: Optional[bool] = False,
output_hidden_states: Optional[bool] = False,
return_dict: Optional[bool] = True,
) -> Union[Tuple, BaseModelOutputWithCrossAttentions]:
all_hidden_states = () if output_hidden_states else None
all_self_attentions = () if output_attentions else None
all_cross_attentions = () if output_attentions else None
# Apply the cross-attention between the latents (hidden_states) and inputs:
layer_outputs = self.cross_attention(
hidden_states,
attention_mask=attention_mask,
head_mask=None,
inputs=inputs,
inputs_mask=inputs_mask,
output_attentions=output_attentions,
)
hidden_states = layer_outputs[0]
if output_attentions:
all_cross_attentions = all_cross_attentions + (layer_outputs[1],)
# Apply the block of self-attention layers more than once:
for _ in range(self.config.num_blocks):
for i, layer_module in enumerate(self.self_attends):
if output_hidden_states:
all_hidden_states = all_hidden_states + (hidden_states,)
layer_head_mask = head_mask[i] if head_mask is not None else None
layer_outputs = layer_module(
hidden_states,
attention_mask=attention_mask,
head_mask=layer_head_mask,
output_attentions=output_attentions,
)
hidden_states = layer_outputs[0]
if output_attentions:
all_self_attentions = all_self_attentions + (layer_outputs[1],)
if output_hidden_states:
all_hidden_states = all_hidden_states + (hidden_states,)
if not return_dict:
return tuple(
v
for v in [hidden_states, all_hidden_states, all_self_attentions, all_cross_attentions]
if v is not None
)
return BaseModelOutputWithCrossAttentions(
last_hidden_state=hidden_states,
hidden_states=all_hidden_states,
attentions=all_self_attentions,
cross_attentions=all_cross_attentions,
)
class PerceiverPreTrainedModel(PreTrainedModel):
"""
An abstract class to handle weights initialization and a simple interface for downloading and loading pretrained
models.
"""
config_class = PerceiverConfig
base_model_prefix = "perceiver"
main_input_name = "inputs"
def _init_weights(self, module):
"""Initialize the weights"""
if isinstance(module, (nn.Linear, nn.Conv2d)):
# Slightly different from the TF version which uses truncated_normal for initialization
# cf https://github.com/pytorch/pytorch/pull/5617
module.weight.data.normal_(mean=0.0, std=self.config.initializer_range)
if module.bias is not None:
module.bias.data.zero_()
elif hasattr(module, "latents"):
module.latents.data.normal_(mean=0.0, std=self.config.initializer_range)
elif hasattr(module, "position_embeddings") and isinstance(module, PerceiverTrainablePositionEncoding):
module.position_embeddings.data.normal_(mean=0.0, std=self.config.initializer_range)
elif isinstance(module, nn.ParameterDict):
for modality in module.keys():
module[modality].data.normal_(mean=0.0, std=self.config.initializer_range)
elif isinstance(module, nn.Embedding):
module.weight.data.normal_(mean=0.0, std=self.config.initializer_range)
if module.padding_idx is not None:
module.weight.data[module.padding_idx].zero_()
elif isinstance(module, nn.LayerNorm):
module.bias.data.zero_()
module.weight.data.fill_(1.0)
PERCEIVER_START_DOCSTRING = r"""
This model is a PyTorch [torch.nn.Module](https://pytorch.org/docs/stable/nn.html#torch.nn.Module) sub-class. Use
it as a regular PyTorch Module and refer to the PyTorch documentation for all matter related to general usage and
behavior.
Parameters:
config ([`PerceiverConfig`]): Model configuration class with all the parameters of the model.
Initializing with a config file does not load the weights associated with the model, only the
configuration. Check out the [`~PreTrainedModel.from_pretrained`] method to load the model weights.
"""
PERCEIVER_MODEL_START_DOCSTRING = r"""
This model is a PyTorch [torch.nn.Module](https://pytorch.org/docs/stable/nn.html#torch.nn.Module) sub-class. Use
it as a regular PyTorch Module and refer to the PyTorch documentation for all matter related to general usage and
behavior.
Parameters:
config ([`PerceiverConfig`]): Model configuration class with all the parameters of the model.
Initializing with a config file does not load the weights associated with the model, only the
configuration. Check out the [`~PreTrainedModel.from_pretrained`] method to load the model weights.
decoder (*DecoderType*, *optional*):
Optional decoder to use to decode the latent representation of the encoder. Examples include
*transformers.models.perceiver.modeling_perceiver.PerceiverBasicDecoder*,
*transformers.models.perceiver.modeling_perceiver.PerceiverClassificationDecoder*,
*transformers.models.perceiver.modeling_perceiver.PerceiverMultimodalDecoder*.
input_preprocessor (*PreprocessorType*, *optional*):
Optional input preprocessor to use. Examples include
*transformers.models.perceiver.modeling_perceiver.PerceiverImagePreprocessor*,
*transformers.models.perceiver.modeling_perceiver.PerceiverAudioPreprocessor*,
*transformers.models.perceiver.modeling_perceiver.PerceiverTextPreprocessor*,
*transformers.models.perceiver.modeling_perceiver.PerceiverMultimodalPreprocessor*.
output_postprocessor (*PostprocessorType*, *optional*):
Optional output postprocessor to use. Examples include
*transformers.models.perceiver.modeling_perceiver.PerceiverImagePostprocessor*,
*transformers.models.perceiver.modeling_perceiver.PerceiverAudioPostprocessor*,
*transformers.models.perceiver.modeling_perceiver.PerceiverClassificationPostprocessor*,
*transformers.models.perceiver.modeling_perceiver.PerceiverProjectionPostprocessor*,
*transformers.models.perceiver.modeling_perceiver.PerceiverMultimodalPostprocessor*.
Note that you can define your own decoders, preprocessors and/or postprocessors to fit your use-case.
"""
PERCEIVER_INPUTS_DOCSTRING = r"""
Args:
inputs (`torch.FloatTensor`):
Inputs to the perceiver. Can be anything: images, text, audio, video, etc.
attention_mask (`torch.FloatTensor` of shape `{0}`, *optional*):
Mask to avoid performing attention on padding token indices. Mask values selected in `[0, 1]`:
- 1 for tokens that are **not masked**,
- 0 for tokens that are **masked**.
[What are attention masks?](../glossary#attention-mask)
head_mask (`torch.FloatTensor` of shape `(num_heads,)` or `(num_layers, num_heads)`, *optional*):
Mask to nullify selected heads of the self-attention modules. Mask values selected in `[0, 1]`:
- 1 indicates the head is **not masked**,
- 0 indicates the head is **masked**.
output_attentions (`bool`, *optional*):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under returned
tensors for more detail.
output_hidden_states (`bool`, *optional*):
Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors for
more detail.
return_dict (`bool`, *optional*):
Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
"""
@add_start_docstrings(
"""The Perceiver: a scalable, fully attentional architecture.""",
PERCEIVER_MODEL_START_DOCSTRING,
)
class PerceiverModel(PerceiverPreTrainedModel):
def __init__(
self,
config,
decoder=None,
input_preprocessor: PreprocessorType = None,
output_postprocessor: PostprocessorType = None,
):
super().__init__(config)
self.config = config
self.input_preprocessor = input_preprocessor
self.output_postprocessor = output_postprocessor
self.embeddings = PerceiverEmbeddings(config)
self.encoder = PerceiverEncoder(
config, kv_dim=input_preprocessor.num_channels if input_preprocessor is not None else config.d_model
)
self.decoder = decoder
# Initialize weights and apply final processing
self.post_init()
def get_input_embeddings(self):
return self.embeddings.latents
def set_input_embeddings(self, value):
self.embeddings.latents = value
def _prune_heads(self, heads_to_prune):
"""
Prunes heads of the model. heads_to_prune: dict of {layer_num: list of heads to prune in this layer} See base
class PreTrainedModel
"""
for layer, heads in heads_to_prune.items():
self.encoder.layer[layer].attention.prune_heads(heads)
@add_start_docstrings_to_model_forward(PERCEIVER_INPUTS_DOCSTRING.format("(batch_size, sequence_length)"))
@replace_return_docstrings(output_type=PerceiverModelOutput, config_class=_CONFIG_FOR_DOC)
def forward(
self,
inputs: torch.FloatTensor,
attention_mask: Optional[torch.FloatTensor] = None,
subsampled_output_points: Optional[Dict[str, torch.Tensor]] = None,
head_mask: Optional[torch.FloatTensor] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
return_dict: Optional[bool] = None,
) -> Union[Tuple, PerceiverModelOutput]:
r"""
Returns:
Examples:
```python
>>> from transformers import PerceiverConfig, PerceiverTokenizer, PerceiverImageProcessor, PerceiverModel
>>> from transformers.models.perceiver.modeling_perceiver import (
... PerceiverTextPreprocessor,
... PerceiverImagePreprocessor,
... PerceiverClassificationDecoder,
... )
>>> import torch
>>> import requests
>>> from PIL import Image
>>> # EXAMPLE 1: using the Perceiver to classify texts
>>> # - we define a TextPreprocessor, which can be used to embed tokens
>>> # - we define a ClassificationDecoder, which can be used to decode the
>>> # final hidden states of the latents to classification logits
>>> # using trainable position embeddings
>>> config = PerceiverConfig()
>>> preprocessor = PerceiverTextPreprocessor(config)
>>> decoder = PerceiverClassificationDecoder(
... config,
... num_channels=config.d_latents,
... trainable_position_encoding_kwargs=dict(num_channels=config.d_latents, index_dims=1),
... use_query_residual=True,
... )
>>> model = PerceiverModel(config, input_preprocessor=preprocessor, decoder=decoder)
>>> # you can then do a forward pass as follows:
>>> tokenizer = PerceiverTokenizer()
>>> text = "hello world"
>>> inputs = tokenizer(text, return_tensors="pt").input_ids
>>> with torch.no_grad():
... outputs = model(inputs=inputs)
>>> logits = outputs.logits
>>> list(logits.shape)
[1, 2]
>>> # to train, one can train the model using standard cross-entropy:
>>> criterion = torch.nn.CrossEntropyLoss()
>>> labels = torch.tensor([1])
>>> loss = criterion(logits, labels)
>>> # EXAMPLE 2: using the Perceiver to classify images
>>> # - we define an ImagePreprocessor, which can be used to embed images
>>> config = PerceiverConfig(image_size=224)
>>> preprocessor = PerceiverImagePreprocessor(
... config,
... prep_type="conv1x1",
... spatial_downsample=1,
... out_channels=256,
... position_encoding_type="trainable",
... concat_or_add_pos="concat",
... project_pos_dim=256,
... trainable_position_encoding_kwargs=dict(
... num_channels=256,
... index_dims=config.image_size**2,
... ),
... )
>>> model = PerceiverModel(
... config,
... input_preprocessor=preprocessor,
... decoder=PerceiverClassificationDecoder(
... config,
... num_channels=config.d_latents,
... trainable_position_encoding_kwargs=dict(num_channels=config.d_latents, index_dims=1),
... use_query_residual=True,
... ),
... )
>>> # you can then do a forward pass as follows:
>>> image_processor = PerceiverImageProcessor()
>>> url = "http://images.cocodataset.org/val2017/000000039769.jpg"
>>> image = Image.open(requests.get(url, stream=True).raw)
>>> inputs = image_processor(image, return_tensors="pt").pixel_values
>>> with torch.no_grad():
... outputs = model(inputs=inputs)
>>> logits = outputs.logits
>>> list(logits.shape)
[1, 2]
>>> # to train, one can train the model using standard cross-entropy:
>>> criterion = torch.nn.CrossEntropyLoss()
>>> labels = torch.tensor([1])
>>> loss = criterion(logits, labels)
```"""
output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
)
return_dict = return_dict if return_dict is not None else self.config.use_return_dict
if self.input_preprocessor is not None:
inputs, modality_sizes, inputs_without_pos = self.input_preprocessor(inputs)
else:
modality_sizes = None
inputs_without_pos = None
if inputs.size()[-1] != self.config.d_model:
raise ValueError(
f"Last dimension of the inputs: {inputs.size()[-1]} doesn't correspond to config.d_model:"
f" {self.config.d_model}. Make sure to set config.d_model appropriately."
)
batch_size, seq_length, _ = inputs.size()
device = inputs.device
# If no attention mask is provided, make them all ones
if attention_mask is None:
attention_mask = torch.ones((batch_size, seq_length), device=device)
# Make the attention mask broadcastable to [batch_size, num_heads, seq_length, seq_length]
extended_attention_mask = self.invert_attention_mask(attention_mask)
# Prepare head mask if needed
# 1.0 in head_mask indicate we keep the head
# attention_probs has shape bsz x n_heads x N x N
# input head_mask has shape [num_heads] or [num_blocks x num_heads]
# and head_mask is converted to shape [num_blocks x batch x num_heads x N x N]
head_mask = self.get_head_mask(head_mask, self.config.num_blocks * self.config.num_self_attends_per_block)
embedding_output = self.embeddings(batch_size=batch_size)
encoder_outputs = self.encoder(
embedding_output,
attention_mask=None,
head_mask=head_mask,
inputs=inputs,
inputs_mask=extended_attention_mask,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
return_dict=return_dict,
)
sequence_output = encoder_outputs[0]
logits = None
if self.decoder:
if subsampled_output_points is not None:
output_modality_sizes = {
"audio": subsampled_output_points["audio"].shape[0],
"image": subsampled_output_points["image"].shape[0],
"label": 1,
}
else:
output_modality_sizes = modality_sizes
decoder_query = self.decoder.decoder_query(
inputs, modality_sizes, inputs_without_pos, subsampled_points=subsampled_output_points
)
decoder_outputs = self.decoder(
decoder_query,
z=sequence_output,
query_mask=extended_attention_mask,
output_attentions=output_attentions,
)
logits = decoder_outputs.logits
# add cross-attentions of decoder
if output_attentions and decoder_outputs.cross_attentions is not None:
if return_dict:
encoder_outputs.cross_attentions = (
encoder_outputs.cross_attentions + decoder_outputs.cross_attentions
)
else:
encoder_outputs = encoder_outputs + decoder_outputs.cross_attentions
if self.output_postprocessor:
logits = self.output_postprocessor(logits, modality_sizes=output_modality_sizes)
if not return_dict:
if logits is not None:
return (logits, sequence_output) + encoder_outputs[1:]
else:
return (sequence_output,) + encoder_outputs[1:]
return PerceiverModelOutput(
logits=logits,
last_hidden_state=sequence_output,
hidden_states=encoder_outputs.hidden_states,
attentions=encoder_outputs.attentions,
cross_attentions=encoder_outputs.cross_attentions,
)
@add_start_docstrings("""Example use of Perceiver for masked language modeling.""", PERCEIVER_START_DOCSTRING)
class PerceiverForMaskedLM(PerceiverPreTrainedModel):
def __init__(self, config: PerceiverConfig):
super().__init__(config)
text_preprocessor = PerceiverTextPreprocessor(config)
trainable_position_encoding_kwargs_decoder = {
"num_channels": text_preprocessor.num_channels,
"index_dims": config.max_position_embeddings,
}
self.perceiver = PerceiverModel(
config,
input_preprocessor=text_preprocessor,
decoder=PerceiverBasicDecoder(
config,
output_num_channels=config.d_latents,
output_index_dims=config.max_position_embeddings, # we need to define the seq_len of the inputs beforehand
num_channels=text_preprocessor.num_channels,
qk_channels=8 * 32,
v_channels=text_preprocessor.num_channels,
num_heads=8,
use_query_residual=False,
final_project=False,
trainable_position_encoding_kwargs=trainable_position_encoding_kwargs_decoder,
),
)
self.embedding_decoder = PerceiverEmbeddingDecoder(config)
# Initialize weights and apply final processing
self.post_init()
@add_start_docstrings_to_model_forward(PERCEIVER_INPUTS_DOCSTRING.format("batch_size, sequence_length"))
@replace_return_docstrings(output_type=PerceiverMaskedLMOutput, config_class=_CONFIG_FOR_DOC)
def forward(
self,
inputs: Optional[torch.Tensor] = None,
attention_mask: Optional[torch.Tensor] = None,
head_mask: Optional[torch.Tensor] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
labels: Optional[torch.Tensor] = None,
return_dict: Optional[bool] = None,
input_ids: Optional[torch.Tensor] = None,
) -> Union[Tuple, PerceiverMaskedLMOutput]:
r"""
labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):