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# coding=utf-8
# Copyright 2018 Google AI, Google Brain and Carnegie Mellon University Authors and the HuggingFace Inc. team.
# Copyright (c) 2018, NVIDIA CORPORATION. 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.
"""XLNet configuration"""
import warnings
from ...configuration_utils import PretrainedConfig
from ...utils import logging
logger = logging.get_logger(__name__)
class XLNetConfig(PretrainedConfig):
"""
This is the configuration class to store the configuration of a [`XLNetModel`] or a [`TFXLNetModel`]. It is used to
instantiate a XLNet model according to the specified arguments, defining the model architecture. Instantiating a
configuration with the defaults will yield a similar configuration to that of the
[xlnet/xlnet-large-cased](https://huggingface.co/xlnet/xlnet-large-cased) architecture.
Configuration objects inherit from [`PretrainedConfig`] and can be used to control the model outputs. Read the
documentation from [`PretrainedConfig`] for more information.
Args:
vocab_size (`int`, *optional*, defaults to 32000):
Vocabulary size of the XLNet model. Defines the number of different tokens that can be represented by the
`inputs_ids` passed when calling [`XLNetModel`] or [`TFXLNetModel`].
d_model (`int`, *optional*, defaults to 1024):
Dimensionality of the encoder layers and the pooler layer.
n_layer (`int`, *optional*, defaults to 24):
Number of hidden layers in the Transformer encoder.
n_head (`int`, *optional*, defaults to 16):
Number of attention heads for each attention layer in the Transformer encoder.
d_inner (`int`, *optional*, defaults to 4096):
Dimensionality of the "intermediate" (often named feed-forward) layer in the Transformer encoder.
ff_activation (`str` or `Callable`, *optional*, defaults to `"gelu"`):
The non-linear activation function (function or string) in the If string, `"gelu"`, `"relu"`, `"silu"` and
`"gelu_new"` are supported.
untie_r (`bool`, *optional*, defaults to `True`):
Whether or not to untie relative position biases
attn_type (`str`, *optional*, defaults to `"bi"`):
The attention type used by the model. Set `"bi"` for XLNet, `"uni"` for Transformer-XL.
initializer_range (`float`, *optional*, defaults to 0.02):
The standard deviation of the truncated_normal_initializer for initializing all weight matrices.
layer_norm_eps (`float`, *optional*, defaults to 1e-12):
The epsilon used by the layer normalization layers.
dropout (`float`, *optional*, defaults to 0.1):
The dropout probability for all fully connected layers in the embeddings, encoder, and pooler.
mem_len (`int` or `None`, *optional*):
The number of tokens to cache. The key/value pairs that have already been pre-computed in a previous
forward pass won't be re-computed. See the
[quickstart](https://huggingface.co/transformers/quickstart.html#using-the-past) for more information.
reuse_len (`int`, *optional*):
The number of tokens in the current batch to be cached and reused in the future.
bi_data (`bool`, *optional*, defaults to `False`):
Whether or not to use bidirectional input pipeline. Usually set to `True` during pretraining and `False`
during finetuning.
clamp_len (`int`, *optional*, defaults to -1):
Clamp all relative distances larger than clamp_len. Setting this attribute to -1 means no clamping.
same_length (`bool`, *optional*, defaults to `False`):
Whether or not to use the same attention length for each token.
summary_type (`str`, *optional*, defaults to "last"):
Argument used when doing sequence summary. Used in the sequence classification and multiple choice models.
Has to be one of the following options:
- `"last"`: Take the last token hidden state (like XLNet).
- `"first"`: Take the first token hidden state (like BERT).
- `"mean"`: Take the mean of all tokens hidden states.
- `"cls_index"`: Supply a Tensor of classification token position (like GPT/GPT-2).
- `"attn"`: Not implemented now, use multi-head attention.
summary_use_proj (`bool`, *optional*, defaults to `True`):
Argument used when doing sequence summary. Used in the sequence classification and multiple choice models.
Whether or not to add a projection after the vector extraction.
summary_activation (`str`, *optional*):
Argument used when doing sequence summary. Used in the sequence classification and multiple choice models.
Pass `"tanh"` for a tanh activation to the output, any other value will result in no activation.
summary_proj_to_labels (`boo`, *optional*, defaults to `True`):
Used in the sequence classification and multiple choice models.
Whether the projection outputs should have `config.num_labels` or `config.hidden_size` classes.
summary_last_dropout (`float`, *optional*, defaults to 0.1):
Used in the sequence classification and multiple choice models.
The dropout ratio to be used after the projection and activation.
start_n_top (`int`, *optional*, defaults to 5):
Used in the SQuAD evaluation script.
end_n_top (`int`, *optional*, defaults to 5):
Used in the SQuAD evaluation script.
use_mems_eval (`bool`, *optional*, defaults to `True`):
Whether or not the model should make use of the recurrent memory mechanism in evaluation mode.
use_mems_train (`bool`, *optional*, defaults to `False`):
Whether or not the model should make use of the recurrent memory mechanism in train mode.
<Tip>
For pretraining, it is recommended to set `use_mems_train` to `True`. For fine-tuning, it is recommended to
set `use_mems_train` to `False` as discussed
[here](https://github.com/zihangdai/xlnet/issues/41#issuecomment-505102587). If `use_mems_train` is set to
`True`, one has to make sure that the train batches are correctly pre-processed, *e.g.* `batch_1 = [[This
line is], [This is the]]` and `batch_2 = [[ the first line], [ second line]]` and that all batches are of
equal size.
</Tip>
Examples:
```python
>>> from transformers import XLNetConfig, XLNetModel
>>> # Initializing a XLNet configuration
>>> configuration = XLNetConfig()
>>> # Initializing a model (with random weights) from the configuration
>>> model = XLNetModel(configuration)
>>> # Accessing the model configuration
>>> configuration = model.config
```"""
model_type = "xlnet"
keys_to_ignore_at_inference = ["mems"]
attribute_map = {
"n_token": "vocab_size", # Backward compatibility
"hidden_size": "d_model",
"num_attention_heads": "n_head",
"num_hidden_layers": "n_layer",
}
def __init__(
self,
vocab_size=32000,
d_model=1024,
n_layer=24,
n_head=16,
d_inner=4096,
ff_activation="gelu",
untie_r=True,
attn_type="bi",
initializer_range=0.02,
layer_norm_eps=1e-12,
dropout=0.1,
mem_len=512,
reuse_len=None,
use_mems_eval=True,
use_mems_train=False,
bi_data=False,
clamp_len=-1,
same_length=False,
summary_type="last",
summary_use_proj=True,
summary_activation="tanh",
summary_last_dropout=0.1,
start_n_top=5,
end_n_top=5,
pad_token_id=5,
bos_token_id=1,
eos_token_id=2,
**kwargs,
):
"""Constructs XLNetConfig."""
self.vocab_size = vocab_size
self.d_model = d_model
self.n_layer = n_layer
self.n_head = n_head
if d_model % n_head != 0:
raise ValueError(f"'d_model % n_head' ({d_model % n_head}) should be equal to 0")
if "d_head" in kwargs:
if kwargs["d_head"] != d_model // n_head:
raise ValueError(
f"`d_head` ({kwargs['d_head']}) should be equal to `d_model // n_head` ({d_model // n_head})"
)
self.d_head = d_model // n_head
self.ff_activation = ff_activation
self.d_inner = d_inner
self.untie_r = untie_r
self.attn_type = attn_type
self.initializer_range = initializer_range
self.layer_norm_eps = layer_norm_eps
self.dropout = dropout
self.mem_len = mem_len
self.reuse_len = reuse_len
self.bi_data = bi_data
self.clamp_len = clamp_len
self.same_length = same_length
self.summary_type = summary_type
self.summary_use_proj = summary_use_proj
self.summary_activation = summary_activation
self.summary_last_dropout = summary_last_dropout
self.start_n_top = start_n_top
self.end_n_top = end_n_top
self.bos_token_id = bos_token_id
self.pad_token_id = pad_token_id
self.eos_token_id = eos_token_id
if "use_cache" in kwargs:
warnings.warn(
"The `use_cache` argument is deprecated and will be removed in a future version, use `use_mems_eval`"
" instead.",
FutureWarning,
)
use_mems_eval = kwargs["use_cache"]
self.use_mems_eval = use_mems_eval
self.use_mems_train = use_mems_train
super().__init__(pad_token_id=pad_token_id, bos_token_id=bos_token_id, eos_token_id=eos_token_id, **kwargs)
@property
def max_position_embeddings(self):
logger.info(f"The model {self.model_type} is one of the few models that has no sequence length limit.")
return -1
@max_position_embeddings.setter
def max_position_embeddings(self, value):
# Message copied from Transformer-XL documentation
raise NotImplementedError(
f"The model {self.model_type} is one of the few models that has no sequence length limit."
)
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