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Zero
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# Copyright 2023-present the HuggingFace Inc. team.
#
# 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.
import math
import torch
from peft.utils.integrations import gather_params_ctx
from .config import PromptTuningInit
class PromptEmbedding(torch.nn.Module):
"""
The model to encode virtual tokens into prompt embeddings.
Args:
config ([`PromptTuningConfig`]): The configuration of the prompt embedding.
word_embeddings (`torch.nn.Module`): The word embeddings of the base transformer model.
**Attributes**:
- **embedding** (`torch.nn.Embedding`) -- The embedding layer of the prompt embedding.
Example:
```py
>>> from peft import PromptEmbedding, PromptTuningConfig
>>> config = PromptTuningConfig(
... peft_type="PROMPT_TUNING",
... task_type="SEQ_2_SEQ_LM",
... num_virtual_tokens=20,
... token_dim=768,
... num_transformer_submodules=1,
... num_attention_heads=12,
... num_layers=12,
... prompt_tuning_init="TEXT",
... prompt_tuning_init_text="Predict if sentiment of this review is positive, negative or neutral",
... tokenizer_name_or_path="t5-base",
... )
>>> # t5_model.shared is the word embeddings of the base model
>>> prompt_embedding = PromptEmbedding(config, t5_model.shared)
```
Input Shape: (`batch_size`, `total_virtual_tokens`)
Output Shape: (`batch_size`, `total_virtual_tokens`, `token_dim`)
"""
def __init__(self, config, word_embeddings):
super().__init__()
total_virtual_tokens = config.num_virtual_tokens * config.num_transformer_submodules
self.embedding = torch.nn.Embedding(total_virtual_tokens, config.token_dim)
if config.prompt_tuning_init == PromptTuningInit.TEXT and not config.inference_mode:
from transformers import AutoTokenizer
tokenizer_kwargs = config.tokenizer_kwargs or {}
tokenizer = AutoTokenizer.from_pretrained(config.tokenizer_name_or_path, **tokenizer_kwargs)
init_text = config.prompt_tuning_init_text
init_token_ids = tokenizer(init_text)["input_ids"]
# Trim or iterate until num_text_tokens matches total_virtual_tokens
num_text_tokens = len(init_token_ids)
if num_text_tokens > total_virtual_tokens:
init_token_ids = init_token_ids[:total_virtual_tokens]
elif num_text_tokens < total_virtual_tokens:
num_reps = math.ceil(total_virtual_tokens / num_text_tokens)
init_token_ids = init_token_ids * num_reps
init_token_ids = init_token_ids[:total_virtual_tokens]
init_token_ids = torch.LongTensor(init_token_ids).to(word_embeddings.weight.device)
with gather_params_ctx(word_embeddings.parameters()):
word_embedding_weights = word_embeddings(init_token_ids).detach().clone()
word_embedding_weights = word_embedding_weights.to(torch.float32)
self.embedding.weight = torch.nn.Parameter(word_embedding_weights)
def forward(self, indices):
# Just get embeddings
prompt_embeddings = self.embedding(indices)
return prompt_embeddings
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