补充最新代码

This commit is contained in:
kjq_glb 2024-05-28 18:20:54 +08:00
parent 310cdb21f5
commit 7a18d5b868
16 changed files with 1849 additions and 101 deletions

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@ -7,10 +7,19 @@
"id": "c024bfa4-1a7a-4751-b5a1-827225a3478b"
},
"source": [
"<font size=\"1\">\n",
"Supplementary code for \"Build a Large Language Model From Scratch\": <a href=\"https://www.manning.com/books/build-a-large-language-model-from-scratch\">https://www.manning.com/books/build-a-large-language-model-from-scratch</a> by <a href=\"https://sebastianraschka.com\">Sebastian Raschka</a><br>\n",
"Code repository: <a href=\"https://github.com/rasbt/LLMs-from-scratch\">https://github.com/rasbt/LLMs-from-scratch</a>\n",
"</font>"
"<table style=\"width:100%\">\n",
"<tr>\n",
"<td style=\"vertical-align:middle; text-align:left;\">\n",
"<font size=\"2\">\n",
"Supplementary code for the <a href=\"http://mng.bz/orYv\">Build a Large Language Model From Scratch</a> book by <a href=\"https://sebastianraschka.com\">Sebastian Raschka</a><br>\n",
"<br>Code repository: <a href=\"https://github.com/rasbt/LLMs-from-scratch\">https://github.com/rasbt/LLMs-from-scratch</a>\n",
"</font>\n",
"</td>\n",
"<td style=\"vertical-align:middle; text-align:left;\">\n",
"<a href=\"http://mng.bz/orYv\"><img src=\"https://sebastianraschka.com/images/LLMs-from-scratch-images/cover-small.webp\" width=\"100px\"></a>\n",
"</td>\n",
"</tr>\n",
"</table>"
]
},
{
@ -907,7 +916,7 @@
"id": "ab8e056c-abe0-415f-b34d-df686204259e",
"metadata": {},
"source": [
"- To ensure that the model was loaded corrected, let's double-check that it generates coherent text"
"- 为了确保模型加载正确,让我们仔细检查它是否生成连贯的文本。"
]
},
{
@ -951,7 +960,7 @@
"id": "69162550-6a02-4ece-8db1-06c71d61946f",
"metadata": {},
"source": [
"- Before we finetune the model as a classifier, let's see if the model can perhaps already classify spam messages via prompting"
"- 在我们将模型微调为分类器之前,让我们看看模型是否已经可以通过提示对垃圾邮件进行分类。"
]
},
{
@ -991,8 +1000,8 @@
"id": "1ce39ed0-2c77-410d-8392-dd15d4b22016",
"metadata": {},
"source": [
"- As we can see, the model is not very good at following instructions\n",
"- This is expected, since it has only been pretrained and not instruction-finetuned (instruction finetuning will be covered in the next chapter)"
"- 正如我们所看到的,该模型不太擅长遵循指令\n",
"- 这是预料之中的,因为它只经过了预训练,没有进行指令微调(指令微调将在下一章中介绍)"
]
},
{

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@ -5,10 +5,19 @@
"id": "ba450fb1-8a26-4894-ab7a-5d7bfefe90ce",
"metadata": {},
"source": [
"<font size=\"1\">\n",
"Supplementary code for \"Build a Large Language Model From Scratch\": <a href=\"https://www.manning.com/books/build-a-large-language-model-from-scratch\">https://www.manning.com/books/build-a-large-language-model-from-scratch</a> by <a href=\"https://sebastianraschka.com\">Sebastian Raschka</a><br>\n",
"Code repository: <a href=\"https://github.com/rasbt/LLMs-from-scratch\">https://github.com/rasbt/LLMs-from-scratch</a>\n",
"</font>"
"<table style=\"width:100%\">\n",
"<tr>\n",
"<td style=\"vertical-align:middle; text-align:left;\">\n",
"<font size=\"2\">\n",
"Supplementary code for the <a href=\"http://mng.bz/orYv\">Build a Large Language Model From Scratch</a> book by <a href=\"https://sebastianraschka.com\">Sebastian Raschka</a><br>\n",
"<br>Code repository: <a href=\"https://github.com/rasbt/LLMs-from-scratch\">https://github.com/rasbt/LLMs-from-scratch</a>\n",
"</font>\n",
"</td>\n",
"<td style=\"vertical-align:middle; text-align:left;\">\n",
"<a href=\"http://mng.bz/orYv\"><img src=\"https://sebastianraschka.com/images/LLMs-from-scratch-images/cover-small.webp\" width=\"100px\"></a>\n",
"</td>\n",
"</tr>\n",
"</table>"
]
},
{

View File

@ -21,11 +21,30 @@ from gpt_download import download_and_load_gpt2
from previous_chapters import GPTModel, load_weights_into_gpt
def download_and_unzip_spam_data(url, zip_path, extracted_path, data_file_path):
def download_and_unzip_spam_data(url, zip_path, extracted_path, data_file_path, test_mode=False):
if data_file_path.exists():
print(f"{data_file_path} already exists. Skipping download and extraction.")
return
if test_mode: # Try multiple times since CI sometimes has connectivity issues
max_retries = 5
delay = 5 # delay between retries in seconds
for attempt in range(max_retries):
try:
# Downloading the file
with urllib.request.urlopen(url, timeout=10) as response:
with open(zip_path, "wb") as out_file:
out_file.write(response.read())
break # if download is successful, break out of the loop
except urllib.error.URLError as e:
print(f"Attempt {attempt + 1} failed: {e}")
if attempt < max_retries - 1:
time.sleep(delay) # wait before retrying
else:
print("Failed to download file after several attempts.")
return # exit if all retries fail
else: # Code as it appears in the chapter
# Downloading the file
with urllib.request.urlopen(url) as response:
with open(zip_path, "wb") as out_file:
@ -238,6 +257,7 @@ if __name__ == "__main__":
)
parser.add_argument(
"--test_mode",
default=False,
action="store_true",
help=("This flag runs the model in test mode for internal testing purposes. "
"Otherwise, it runs the model as it is used in the chapter (recommended).")
@ -253,7 +273,7 @@ if __name__ == "__main__":
extracted_path = "sms_spam_collection"
data_file_path = Path(extracted_path) / "SMSSpamCollection.tsv"
download_and_unzip_spam_data(url, zip_path, extracted_path, data_file_path)
download_and_unzip_spam_data(url, zip_path, extracted_path, data_file_path, test_mode=args.test_mode)
df = pd.read_csv(data_file_path, sep="\t", header=None, names=["Label", "Text"])
balanced_df = create_balanced_dataset(df)
balanced_df["Label"] = balanced_df["Label"].map({"ham": 0, "spam": 1})
@ -330,9 +350,7 @@ if __name__ == "__main__":
}
model = GPTModel(BASE_CONFIG)
model.eval()
device = "cpu"
model.to(device)
# Code as it is used in the main chapter
else:
@ -355,15 +373,18 @@ if __name__ == "__main__":
BASE_CONFIG.update(model_configs[CHOOSE_MODEL])
assert train_dataset.max_length <= BASE_CONFIG["context_length"], (
f"Dataset length {train_dataset.max_length} exceeds model's context "
f"length {BASE_CONFIG['context_length']}. Reinitialize data sets with "
f"`max_length={BASE_CONFIG['context_length']}`"
)
model_size = CHOOSE_MODEL.split(" ")[-1].lstrip("(").rstrip(")")
settings, params = download_and_load_gpt2(model_size=model_size, models_dir="gpt2")
model = GPTModel(BASE_CONFIG)
load_weights_into_gpt(model, params)
model.eval()
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
model.to(device)
########################################
# Modify and pretrained model
@ -376,6 +397,7 @@ if __name__ == "__main__":
num_classes = 2
model.out_head = torch.nn.Linear(in_features=BASE_CONFIG["emb_dim"], out_features=num_classes)
model.to(device)
for param in model.trf_blocks[-1].parameters():
param.requires_grad = True

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@ -14,15 +14,18 @@
| 1 | gpt2-small (124M) | pretrained | last | last_block | longest train ex. (120) | 96.63% | 99.33% | 95.00% | 0.28 min | A100 |
| 2 | gpt2-small (124M) | pretrained | first | last_block | longest train ex. (120) | 78.46% | 80.54% | 75.00% | 0.28 min | A100 |
| 3 | gpt2-small (124M) | pretrained | last | last_layer | longest train ex. (120) | 78.65% | 79.87% | 72.00% | 0.25 min | A100 |
| 4 | gpt2-small (124M) | pretrained | last | all | longest train ex. (120) | 99.62% | 96.64% | 96.67% | 0.69 min | A100 |
| 5 | gpt2-medium (355M) | pretrained | last | last_block | longest train ex. (120) | 87.50% | 91.28% | 84.67% | 0.75 min | A100 |
| 6 | gpt2-large (774M) | pretrained | last | last_block | longest train ex. (120) | 99.52% | 98.66% | 96.67% | 1.50 min | A100 |
| 7 | gpt2-xl (1558M) | pretrained | last | last_block | longest train ex. (120) | 99.81% | 99.33% | 98.33% | 2.83 min | A100 |
| 8 | gpt2-small (124M) | random | last | all | longest train ex. (120) | 100% | 96.64% | 93.67% | 0.69 min | A100 |
| 9 | gpt2-small (124M) | pretrained | last | LoRA | longest train ex. (120) | 99.52% | 97.99% | 97.67% | 0.75 min | A100 |
| 10 | gpt2-small (124M) | pretrained | last | last_block | context length (1024) | 83.08% | 87.92% | 78.33% | 2.46 min | A100 |
| 11 | gpt2-small (124M) | pretrained | last | last_block | variable: no padding (batch size 1) | 100.00% | 98.66% | 98.00% | 1.75 min | A100 |
| 11 | gpt2-small (124M) | pretrained | last | last_block | variable: no padding (batch size 8) | 99.33% | 98.66% | 98.33% | 1.70 min | A100 |
| 4 | gpt2-small (124M) | pretrained | last | last_two_blocks | longest train ex. (120) | 98.85% | 98.66% | 98.33% | 0.33 min | A100 |
| 5 | gpt2-small (124M) | pretrained | last | all | longest train ex. (120) | 99.62% | 96.64% | 96.67% | 0.69 min | A100 |
| 6 | gpt2-medium (355M) | pretrained | last | last_block | longest train ex. (120) | 87.50% | 91.28% | 84.67% | 0.75 min | A100 |
| 7 | gpt2-large (774M) | pretrained | last | last_block | longest train ex. (120) | 99.52% | 98.66% | 96.67% | 1.50 min | A100 |
| 8 | gpt2-xl (1558M) | pretrained | last | last_block | longest train ex. (120) | 99.81% | 99.33% | 98.33% | 2.83 min | A100 |
| 9 | gpt2-small (124M) | random | last | all | longest train ex. (120) | 100% | 96.64% | 93.67% | 0.69 min | A100 |
| 10 | gpt2-small (124M) | pretrained | last | LoRA | longest train ex. (120) | 100.00% | 97.32% | 96.67% | 0.75 min | A100 |
| 11 | gpt2-small (124M) | pretrained | last | last_block | context length (1024) | 83.08% | 87.92% | 78.33% | 2.46 min | A100 |
| 12 | gpt2-small (124M) | pretrained | last | last_block | variable: no padding (batch size 1) | 100.00% | 98.66% | 98.00% | 1.75 min | A100 |
| 13 | gpt2-small (124M) | pretrained | last | last_block | variable: no padding (batch size 8) | 99.33% | 98.66% | 98.33% | 1.70 min | A100 |
| 14 | gpt2-small (124M) | pretrained | last | last_block | longest train ex. (120); but no causal mask | 99.23% | 98.66% | 95.33% | 0.29 min | A100 |
| 15 | gpt2-small (124M) | pretrained | last | last_block | longest train ex. (120) and `ignore_index` for padding | 96.63% | 99.33% | 95.00% | 0.28 min | A100 |
&nbsp;
@ -32,17 +35,20 @@
您可以使用以下代码来重现实验:
- Row 1: `python additional-experiments.py`
- Row 2: `python additional-experiments.py --trainable_token first`
- Row 2: `python additional-experiments.py --trainable_token_pos first`
- Row 3: `python additional-experiments.py --trainable_layers last_layer`
- Row 4: `python additional-experiments.py --trainable_layers all`
- Row 5: `python additional-experiments.py --model_size "gpt2-medium (355M)"`
- Row 6: `python additional-experiments.py --model_size "gpt2-large (774M)"`
- Row 7: `python additional-experiments.py --model_size "gpt2-xl (1558M)"`
- Row 8: `python additional-experiments.py --weights random --trainable_layers all`
- Row 9: `python additional-experiments.py --trainable_layers lora --lora_rank 16 --lora_alpha 8`
- Row 10: `python additional-experiments.py --context_length "model_context_length"`
- Row 11: `python additional-experiments.py --no_padding --batch_size 1`
- Row 12: `python additional-experiments.py --no_padding --batch_size 1 --accumulation_steps 8`
- Row 4: `python additional-experiments.py --trainable_layers last_two_blocks`
- Row 5: `python additional-experiments.py --trainable_layers all`
- Row 6: `python additional-experiments.py --model_size "gpt2-medium (355M)"`
- Row 7: `python additional-experiments.py --model_size "gpt2-large (774M)"`
- Row 8: `python additional-experiments.py --model_size "gpt2-xl (1558M)"`
- Row 9: `python additional-experiments.py --weights random --trainable_layers all`
- Row 10: `python additional-experiments.py --trainable_layers lora --lora_rank 16 --lora_alpha 16`
- Row 11: `python additional-experiments.py --context_length "model_context_length"`
- Row 12: `python additional-experiments.py --no_padding --batch_size 1`
- Row 13: `python additional-experiments.py --no_padding --batch_size 1 --accumulation_steps 8`
- Row 14: `python additional-experiments.py --disable_causal_mask`
- Row 15: `python additional-experiments.py --ignore_index 50256`
我特意将 LLM 和数据集保持得较小,因此,如果您无法使用 GPU您可以在 MacBook Air M3 等普通笔记本电脑上运行大约 15 分钟的训练。
@ -50,17 +56,13 @@
## 解释
1. **训练最后一个输出标记与第一个输出标记(第 1 行与第 2 行)**:与第一个输出标记相比,训练最后一个输出标记会带来更好的性能。由于因果自注意力掩模,这种改进是可以预期的。
2. **训练最后一个 Transformer 块与最后一层(第 1 行与第 3 行)**:训练整个最后一个 Transformer 块也比仅训练最后一层获得更好的结果。
3. **训练所有层与最后一个 Transformer 块(第 1 行与第 4 行)**:训练所有层比仅训练最后一个 Transformer 块显示出约 2% 的适度改进,但它需要的时间几乎是三倍的训练时间。
4. **使用更大的预训练模型(第 1 行与第 5 行,以及第 1 行与第 6 行和第 7 行)**:采用 3 倍大的预训练模型会导致更差的结果。 然而,正如预期的那样,与初始模型相比,使用大 5 倍的模型可以提高性能。 同样12 倍大的模型进一步提高了预测性能。(中等模型可能没有经过很好的预训练,或者特定的微调配置对该模型效果不佳。)
5. **使用具有随机权重的模型与预训练权重(第 1 行与第 8 行)**:使用具有随机权重的模型产生的结果仅比使用预训练权重稍差 1.3%。
6. **使用 LoRA低阶适应与训练所有层第 9 行与第 4 行)**:保持模型冻结并添加可训练的 LoRA 层是训练所有模型参数的可行替代方案,甚至可以将性能提高 1%(请参阅[附录 E](../../appendix-E/01_main-chapter-code/appendix-E.ipynb)查看更多细节)。 从使用 LoRA 时训练和验证准确率之间的差距降低 1% 可以看出,这可能是由于过度拟合较少。 此外,使用 LoRA 的速度也稍快一些,因为需要更新的参数较少。
7. **将输入填充到完整上下文长度与最长训练示例(第 1 行与第 10 行)**:将输入填充到完整支持的上下文长度结果明显更差。
8. **填充与无填充(第 1 行与第 11 行和第 12 行)**`--no_padding` 选项禁用数据集中的填充,这需要使用批量大小 1 来训练模型,因为输入具有可变长度。 这会带来更好的测试准确率,但需要更长的训练时间。 在第 12 行中,我们另外启用了 8 个步骤的梯度累积,以实现与其他实验相同的批量大小,这有助于减少过度拟合并略微提高测试集的准确性。
4. **训练最后一个 Transformer 块与所有层(第 1 行与第 5 行)**:训练所有层比仅训练最后一个 Transformer 块显示出约 2% 的适度改进,但就时间而言,它需要几乎三倍的时间训练持续时间。 此外,它仅训练 12 个变压器块中的最后两个,其性能也不佳。
5. **使用更大的预训练模型(第 1 行与第 5 行,以及第 1 行与第 7 行和第 8 行)**:采用 3 倍大的预训练模型会导致更差的结果。然而,正如预期的那样,与初始模型相比,使用大 5 倍的模型可以提高性能。同样12 倍大的模型进一步提高了预测性能。(中等模型可能没有经过很好的预训练,或者特定的微调配置对该模型效果不佳。)
6. **使用具有随机权重的模型与预训练权重(第 1 行与第 9 行)**:使用具有随机权重的模型产生的结果仅比使用预训练权重稍差 1.3%。
7. **使用 LoRA低阶适应与训练所有层第 10 行与第 5 行)**:保持模型冻结并添加可训练的 LoRA 层是训练所有模型参数的可行替代方案(请参阅[附录 E](../../appendix-E/01_main-chapter-code/appendix-E.ipynb)),甚至可以将性能提高 1%。 从使用 LoRA 时训练和验证准确率之间的差距降低约 1% 可以看出,这可能是由于过度拟合较少。此外,使用 LoRA 的速度也稍快一些,因为需要更新的参数较少。
8. **将输入填充到完整上下文长度与最长训练示例(第 1 行与第 11 行)**:将输入填充到完整支持的上下文长度结果明显更差。
9. **填充与无填充(第 1 行与第 12 行和第 13 行)**`--no_padding` 选项禁用数据集中的填充,这需要使用批量大小 1 来训练模型,因为输入具有变量 长度。 这会带来更好的测试精度,但需要更长的训练时间。 在第 12 行中,我们另外启用了 8 个步骤的梯度累积,以实现与其他实验相同的批量大小,这有助于减少过度拟合并略微提高测试集的准确性。
10. **禁用因果注意掩码(第 1 行与第 14 行)**禁用多头注意模块中使用的因果注意掩码。这意味着所有Token都可以参加所有其他Token。 与带有因果掩模的 GPT 模型相比,模型精度略有提高。
11. **忽略损失和反向传播中的填充索引(第 1 行与第 15 行)**:设置 `--ignore_index 50256` 会排除 PyTorch 中 `cross_entropy` 损失函数中的 `|endoftext|` 填充标记。 在这种情况下,它没有任何效果,因为我们替换了输出层,以便二元分类示例的标记 ID 为 0 或 1。 然而,当第 7 章中的指令微调模型时,此设置很有用。

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@ -4,6 +4,7 @@
# Code: https://github.com/rasbt/LLMs-from-scratch
import argparse
import math
import os
from pathlib import Path
import time
@ -23,8 +24,8 @@ from previous_chapters import GPTModel, load_weights_into_gpt
class LoRALayer(torch.nn.Module):
def __init__(self, in_dim, out_dim, rank, alpha):
super().__init__()
std_dev = 1 / torch.sqrt(torch.tensor(rank).float())
self.A = torch.nn.Parameter(torch.randn(in_dim, rank) * std_dev)
self.A = torch.nn.Parameter(torch.empty(in_dim, rank))
torch.nn.init.kaiming_uniform_(self.A, a=math.sqrt(5))
self.B = torch.nn.Parameter(torch.zeros(rank, out_dim))
self.alpha = alpha
@ -153,7 +154,7 @@ def instantiate_model(choose_model, load_weights):
if not load_weights:
torch.manual_seed(123)
model = GPTModel(BASE_CONFIG)
model = GPTModel(BASE_CONFIG, disable_causal_mask=args.disable_causal_mask)
if load_weights:
model_size = choose_model.split(" ")[-1].lstrip("(").rstrip(")")
@ -164,14 +165,16 @@ def instantiate_model(choose_model, load_weights):
return model
def calc_loss_batch(input_batch, target_batch, model, device, trainable_token=-1):
def calc_loss_batch(input_batch, target_batch, model, device,
trainable_token_pos=-1, ignore_index=-100):
input_batch, target_batch = input_batch.to(device), target_batch.to(device)
logits = model(input_batch)[:, trainable_token, :] # Logits of last output token
loss = torch.nn.functional.cross_entropy(logits, target_batch)
logits = model(input_batch)[:, trainable_token_pos, :] # Logits of last output token
loss = torch.nn.functional.cross_entropy(logits, target_batch, ignore_index=ignore_index)
return loss
def calc_loss_loader(data_loader, model, device, num_batches=None, trainable_token=-1):
def calc_loss_loader(data_loader, model, device,
num_batches=None, trainable_token_pos=-1, ignore_index=-100):
total_loss = 0.
if len(data_loader) == 0:
return float("nan")
@ -183,7 +186,10 @@ def calc_loss_loader(data_loader, model, device, num_batches=None, trainable_tok
num_batches = min(num_batches, len(data_loader))
for i, (input_batch, target_batch) in enumerate(data_loader):
if i < num_batches:
loss = calc_loss_batch(input_batch, target_batch, model, device, trainable_token=trainable_token)
loss = calc_loss_batch(
input_batch, target_batch, model, device,
trainable_token_pos=trainable_token_pos, ignore_index=ignore_index
)
total_loss += loss.item()
else:
break
@ -191,7 +197,7 @@ def calc_loss_loader(data_loader, model, device, num_batches=None, trainable_tok
@torch.no_grad() # Disable gradient tracking for efficiency
def calc_accuracy_loader(data_loader, model, device, num_batches=None, trainable_token=-1):
def calc_accuracy_loader(data_loader, model, device, num_batches=None, trainable_token_pos=-1):
model.eval()
correct_predictions, num_examples = 0, 0
@ -202,7 +208,7 @@ def calc_accuracy_loader(data_loader, model, device, num_batches=None, trainable
for i, (input_batch, target_batch) in enumerate(data_loader):
if i < num_batches:
input_batch, target_batch = input_batch.to(device), target_batch.to(device)
logits = model(input_batch)[:, trainable_token, :] # Logits of last output token
logits = model(input_batch)[:, trainable_token_pos, :] # Logits of last output token
predicted_labels = torch.argmax(logits, dim=-1)
num_examples += predicted_labels.shape[0]
@ -212,18 +218,25 @@ def calc_accuracy_loader(data_loader, model, device, num_batches=None, trainable
return correct_predictions / num_examples
def evaluate_model(model, train_loader, val_loader, device, eval_iter, trainable_token=-1):
def evaluate_model(model, train_loader, val_loader, device,
eval_iter, trainable_token_pos=-1, ignore_index=-100):
model.eval()
with torch.no_grad():
train_loss = calc_loss_loader(train_loader, model, device, num_batches=eval_iter, trainable_token=trainable_token)
val_loss = calc_loss_loader(val_loader, model, device, num_batches=eval_iter, trainable_token=trainable_token)
train_loss = calc_loss_loader(
train_loader, model, device, num_batches=eval_iter,
trainable_token_pos=trainable_token_pos, ignore_index=ignore_index
)
val_loss = calc_loss_loader(
val_loader, model, device, num_batches=eval_iter,
trainable_token_pos=trainable_token_pos, ignore_index=ignore_index
)
model.train()
return train_loss, val_loss
def train_classifier_simple(model, train_loader, val_loader, optimizer, device, num_epochs,
eval_freq, eval_iter, tokenizer, max_steps=None, trainable_token=-1,
accumulation_steps=1):
eval_freq, eval_iter, tokenizer, max_steps=None, trainable_token_pos=-1,
accumulation_steps=1, ignore_index=-100):
# Initialize lists to track losses and tokens seen
train_losses, val_losses, train_accs, val_accs = [], [], [], []
examples_seen, global_step = 0, -1
@ -233,7 +246,10 @@ def train_classifier_simple(model, train_loader, val_loader, optimizer, device,
model.train() # Set model to training mode
for batch_idx, (input_batch, target_batch) in enumerate(train_loader):
loss = calc_loss_batch(input_batch, target_batch, model, device, trainable_token=trainable_token)
loss = calc_loss_batch(
input_batch, target_batch, model, device,
trainable_token_pos=trainable_token_pos, ignore_index=ignore_index
)
# Use gradient accumulation if accumulation_steps > 1
# See https://sebastianraschka.com/blog/2023/llm-grad-accumulation.html
@ -253,7 +269,9 @@ def train_classifier_simple(model, train_loader, val_loader, optimizer, device,
# Optional evaluation step
if global_step % eval_freq == 0:
train_loss, val_loss = evaluate_model(
model, train_loader, val_loader, device, eval_iter, trainable_token=trainable_token)
model, train_loader, val_loader, device, eval_iter,
trainable_token_pos=trainable_token_pos, ignore_index=ignore_index
)
train_losses.append(train_loss)
val_losses.append(val_loss)
print(f"Ep {epoch+1} (Step {global_step:06d}): "
@ -263,8 +281,8 @@ def train_classifier_simple(model, train_loader, val_loader, optimizer, device,
break
# New: Calculate accuracy after each epoch
train_accuracy = calc_accuracy_loader(train_loader, model, device, num_batches=eval_iter, trainable_token=trainable_token)
val_accuracy = calc_accuracy_loader(val_loader, model, device, num_batches=eval_iter, trainable_token=trainable_token)
train_accuracy = calc_accuracy_loader(train_loader, model, device, num_batches=eval_iter, trainable_token_pos=trainable_token_pos)
val_accuracy = calc_accuracy_loader(val_loader, model, device, num_batches=eval_iter, trainable_token_pos=trainable_token_pos)
print(f"Training accuracy: {train_accuracy*100:.2f}% | ", end="")
print(f"Validation accuracy: {val_accuracy*100:.2f}%")
train_accs.append(train_accuracy)
@ -311,15 +329,15 @@ if __name__ == "__main__":
type=str,
default="last_block",
help=(
"Which layers to train. Options: 'all', 'last_block', 'last_layer', 'lora'."
"Which layers to train. Options: 'all', 'last_block', 'last_two_blocks', 'last_layer', 'lora'."
)
)
parser.add_argument(
"--trainable_token",
"--trainable_token_pos",
type=str,
default="last",
help=(
"Which token to train. Options: 'first', 'last'."
"Which token position to train. Options: 'first', 'last'."
)
)
parser.add_argument(
@ -386,14 +404,32 @@ if __name__ == "__main__":
)
)
parser.add_argument(
"--disable_causal_mask",
action='store_true',
default=False,
help=(
"Disables the causal attention mask."
)
)
parser.add_argument(
"--ignore_index",
type=int,
default=-100,
help=(
"Sets the `ignore_index` in the cross entropy loss."
)
)
args = parser.parse_args()
if args.trainable_token == "first":
args.trainable_token = 0
elif args.trainable_token == "last":
args.trainable_token = -1
if args.trainable_token_pos == "first":
args.trainable_token_pos = 0
elif args.trainable_token_pos == "last":
args.trainable_token_pos = -1
else:
raise ValueError("Invalid --trainable_token argument")
raise ValueError("Invalid --trainable_token_pos argument")
###############################
# Load model
@ -426,11 +462,14 @@ if __name__ == "__main__":
if args.trainable_layers == "last_layer":
pass
elif args.trainable_layers == "last_block":
elif args.trainable_layers == "last_block" or args.trainable_layers == "last_two_blocks":
for param in model.trf_blocks[-1].parameters():
param.requires_grad = True
for param in model.final_norm.parameters():
param.requires_grad = True
if args.trainable_layers == "last_two_blocks":
for param in model.trf_blocks[-2].parameters():
param.requires_grad = True
elif args.trainable_layers == "all":
for param in model.parameters():
param.requires_grad = True
@ -509,6 +548,12 @@ if __name__ == "__main__":
drop_last=False,
)
assert train_dataset.max_length <= model.pos_emb.weight.shape[0], (
f"Dataset length {train_dataset.max_length} exceeds model's context "
f"length {model.pos_emb.weight.shape[0]}. Reinitialize data sets with "
f"`max_length={model.pos_emb.weight.shape[0]}`"
)
###############################
# Train model
###############################
@ -520,7 +565,7 @@ if __name__ == "__main__":
train_losses, val_losses, train_accs, val_accs, examples_seen = train_classifier_simple(
model, train_loader, val_loader, optimizer, device,
num_epochs=args.num_epochs, eval_freq=50, eval_iter=5,
tokenizer=tokenizer, max_steps=None, trainable_token=args.trainable_token,
tokenizer=tokenizer, max_steps=None, trainable_token_pos=args.trainable_token_pos,
accumulation_steps=args.accumulation_steps
)
@ -532,9 +577,9 @@ if __name__ == "__main__":
# Evaluate model
###############################
train_accuracy = calc_accuracy_loader(train_loader, model, device, trainable_token=args.trainable_token)
val_accuracy = calc_accuracy_loader(val_loader, model, device, trainable_token=args.trainable_token)
test_accuracy = calc_accuracy_loader(test_loader, model, device, trainable_token=args.trainable_token)
train_accuracy = calc_accuracy_loader(train_loader, model, device, trainable_token_pos=args.trainable_token_pos)
val_accuracy = calc_accuracy_loader(val_loader, model, device, trainable_token_pos=args.trainable_token_pos)
test_accuracy = calc_accuracy_loader(test_loader, model, device, trainable_token_pos=args.trainable_token_pos)
print(f"Training accuracy: {train_accuracy*100:.2f}%")
print(f"Validation accuracy: {val_accuracy*100:.2f}%")

View File

@ -60,7 +60,7 @@ def create_dataloader_v1(txt, batch_size=4, max_length=256,
# Chapter 3
#####################################
class MultiHeadAttention(nn.Module):
def __init__(self, d_in, d_out, context_length, dropout, num_heads, qkv_bias=False):
def __init__(self, d_in, d_out, context_length, dropout, num_heads, qkv_bias=False, disable_causal_mask=False):
super().__init__()
assert d_out % num_heads == 0, "d_out must be divisible by n_heads"
@ -73,7 +73,10 @@ class MultiHeadAttention(nn.Module):
self.W_value = nn.Linear(d_in, d_out, bias=qkv_bias)
self.out_proj = nn.Linear(d_out, d_out) # Linear layer to combine head outputs
self.dropout = nn.Dropout(dropout)
if not disable_causal_mask:
self.register_buffer('mask', torch.triu(torch.ones(context_length, context_length), diagonal=1))
self.disable_causal_mask = disable_causal_mask
def forward(self, x):
b, num_tokens, d_in = x.shape
@ -96,6 +99,7 @@ class MultiHeadAttention(nn.Module):
# Compute scaled dot-product attention (aka self-attention) with a causal mask
attn_scores = queries @ keys.transpose(2, 3) # Dot product for each head
if not self.disable_causal_mask:
# Original mask truncated to the number of tokens and converted to boolean
mask_bool = self.mask.bool()[:num_tokens, :num_tokens]
@ -157,7 +161,7 @@ class FeedForward(nn.Module):
class TransformerBlock(nn.Module):
def __init__(self, cfg):
def __init__(self, cfg, disable_causal_mask=False):
super().__init__()
self.att = MultiHeadAttention(
d_in=cfg["emb_dim"],
@ -165,7 +169,9 @@ class TransformerBlock(nn.Module):
context_length=cfg["context_length"],
num_heads=cfg["n_heads"],
dropout=cfg["drop_rate"],
qkv_bias=cfg["qkv_bias"])
qkv_bias=cfg["qkv_bias"],
disable_causal_mask=disable_causal_mask
)
self.ff = FeedForward(cfg)
self.norm1 = LayerNorm(cfg["emb_dim"])
self.norm2 = LayerNorm(cfg["emb_dim"])
@ -190,14 +196,14 @@ class TransformerBlock(nn.Module):
class GPTModel(nn.Module):
def __init__(self, cfg):
def __init__(self, cfg, disable_causal_mask=False):
super().__init__()
self.tok_emb = nn.Embedding(cfg["vocab_size"], cfg["emb_dim"])
self.pos_emb = nn.Embedding(cfg["context_length"], cfg["emb_dim"])
self.drop_emb = nn.Dropout(cfg["drop_rate"])
self.trf_blocks = nn.Sequential(
*[TransformerBlock(cfg) for _ in range(cfg["n_layers"])])
*[TransformerBlock(cfg, disable_causal_mask) for _ in range(cfg["n_layers"])])
self.final_norm = LayerNorm(cfg["emb_dim"])
self.out_head = nn.Linear(cfg["emb_dim"], cfg["vocab_size"], bias=False)
@ -310,7 +316,7 @@ def load_weights_into_gpt(gpt, params):
gpt.out_head.weight = assign(gpt.out_head.weight, params["wte"])
def generate(model, idx, max_new_tokens, context_size, temperature, top_k=None):
def generate(model, idx, max_new_tokens, context_size, temperature=0.0, top_k=None, eos_id=None):
# For-loop is the same as before: Get logits, and only focus on last time step
for _ in range(max_new_tokens):
idx_cond = idx[:, -context_size:]
@ -339,6 +345,9 @@ def generate(model, idx, max_new_tokens, context_size, temperature, top_k=None):
else:
idx_next = torch.argmax(logits, dim=-1, keepdim=True) # (batch_size, 1)
if idx_next == eos_id: # Stop generating early if end-of-sequence token is encountered and eos_id is specified
break
# Same as before: append sampled index to the running sequence
idx = torch.cat((idx, idx_next), dim=1) # (batch_size, num_tokens+1)

View File

@ -0,0 +1,127 @@
# 对 50k IMDB 电影评论的情感进行分类的附加实验
&nbsp;
## Step 1: 安装依赖
通过下列命令安装额外的依赖项
```bash
pip install -r requirements-extra.txt
```
&nbsp;
## Step 2: 下载数据集
这些代码使用 IMDb 中的 50k 电影评论来预测电影评论是正面还是负面。 ([数据集](https://ai.stanford.edu/~amaas/data/sentiment/))
运行以下代码来创建`train.csv`, `validation.csv`, 和 `test.csv`数据集:
```bash
python download-prepare-dataset.py
```
&nbsp;
## Step 3: 运行模型
主要章节中使用的 124M GPT-2 模型,从预训练权重开始,仅训练最后一个 Transformer 块加上输出层:
```bash
python train-gpt.py
```
```
Ep 1 (Step 000000): Train loss 2.829, Val loss 3.433
Ep 1 (Step 000050): Train loss 1.440, Val loss 1.669
Ep 1 (Step 000100): Train loss 0.879, Val loss 1.037
Ep 1 (Step 000150): Train loss 0.838, Val loss 0.866
...
Ep 1 (Step 004300): Train loss 0.174, Val loss 0.202
Ep 1 (Step 004350): Train loss 0.309, Val loss 0.190
Training accuracy: 88.75% | Validation accuracy: 91.25%
Ep 2 (Step 004400): Train loss 0.263, Val loss 0.205
Ep 2 (Step 004450): Train loss 0.226, Val loss 0.188
...
Ep 2 (Step 008650): Train loss 0.189, Val loss 0.171
Ep 2 (Step 008700): Train loss 0.225, Val loss 0.179
Training accuracy: 85.00% | Validation accuracy: 90.62%
Ep 3 (Step 008750): Train loss 0.206, Val loss 0.187
Ep 3 (Step 008800): Train loss 0.198, Val loss 0.172
...
Training accuracy: 96.88% | Validation accuracy: 90.62%
Training completed in 18.62 minutes.
Evaluating on the full datasets ...
Training accuracy: 93.66%
Validation accuracy: 90.02%
Test accuracy: 89.96%
```
---
一个 66M 参数的编码器模型 [DistilBERT](https://arxiv.org/abs/1910.01108)(从 340M 参数 BERT 模型蒸馏而来),从预训练权重开始,仅训练最后一个 Transformer 块和输出层:
```bash
python train-bert-hf.py
```
```
Ep 1 (Step 000000): Train loss 0.693, Val loss 0.697
Ep 1 (Step 000050): Train loss 0.532, Val loss 0.596
Ep 1 (Step 000100): Train loss 0.431, Val loss 0.446
...
Ep 1 (Step 004300): Train loss 0.234, Val loss 0.351
Ep 1 (Step 004350): Train loss 0.190, Val loss 0.222
Training accuracy: 88.75% | Validation accuracy: 88.12%
Ep 2 (Step 004400): Train loss 0.258, Val loss 0.270
Ep 2 (Step 004450): Train loss 0.204, Val loss 0.295
...
Ep 2 (Step 008650): Train loss 0.088, Val loss 0.246
Ep 2 (Step 008700): Train loss 0.084, Val loss 0.247
Training accuracy: 98.75% | Validation accuracy: 90.62%
Ep 3 (Step 008750): Train loss 0.067, Val loss 0.209
Ep 3 (Step 008800): Train loss 0.059, Val loss 0.256
...
Ep 3 (Step 013050): Train loss 0.068, Val loss 0.280
Ep 3 (Step 013100): Train loss 0.064, Val loss 0.306
Training accuracy: 99.38% | Validation accuracy: 87.50%
Training completed in 16.70 minutes.
Evaluating on the full datasets ...
Training accuracy: 98.87%
Validation accuracy: 90.98%
Test accuracy: 90.81%
```
---
一个355M 参数量的编码器模型 [RoBERTa](https://arxiv.org/abs/1907.11692) ,从预训练权重开始,仅训练最后一个 Transformer 块和输出层:
```bash
python train-bert-hf.py --bert_model roberta
```
---
一个scikit-learn Logistic 回归模型作为基线。
```bash
python train-sklearn-logreg.py
```
```
Dummy classifier:
Training Accuracy: 50.01%
Validation Accuracy: 50.14%
Test Accuracy: 49.91%
Logistic regression classifier:
Training Accuracy: 99.80%
Validation Accuracy: 88.60%
Test Accuracy: 88.84%
```

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@ -0,0 +1,84 @@
# Copyright (c) Sebastian Raschka under Apache License 2.0 (see LICENSE.txt).
# Source for "Build a Large Language Model From Scratch"
# - https://www.manning.com/books/build-a-large-language-model-from-scratch
# Code: https://github.com/rasbt/LLMs-from-scratch
import os
import sys
import tarfile
import time
import urllib.request
import pandas as pd
def reporthook(count, block_size, total_size):
global start_time
if count == 0:
start_time = time.time()
else:
duration = time.time() - start_time
progress_size = int(count * block_size)
percent = count * block_size * 100 / total_size
speed = int(progress_size / (1024 * duration)) if duration else 0
sys.stdout.write(
f"\r{int(percent)}% | {progress_size / (1024**2):.2f} MB "
f"| {speed:.2f} MB/s | {duration:.2f} sec elapsed"
)
sys.stdout.flush()
def download_and_extract_dataset(dataset_url, target_file, directory):
if not os.path.exists(directory):
if os.path.exists(target_file):
os.remove(target_file)
urllib.request.urlretrieve(dataset_url, target_file, reporthook)
print("\nExtracting dataset ...")
with tarfile.open(target_file, "r:gz") as tar:
tar.extractall()
else:
print(f"Directory `{directory}` already exists. Skipping download.")
def load_dataset_to_dataframe(basepath="aclImdb", labels={"pos": 1, "neg": 0}):
data_frames = [] # List to store each chunk of DataFrame
for subset in ("test", "train"):
for label in ("pos", "neg"):
path = os.path.join(basepath, subset, label)
for file in sorted(os.listdir(path)):
with open(os.path.join(path, file), "r", encoding="utf-8") as infile:
# Create a DataFrame for each file and add it to the list
data_frames.append(pd.DataFrame({"text": [infile.read()], "label": [labels[label]]}))
# Concatenate all DataFrame chunks together
df = pd.concat(data_frames, ignore_index=True)
df = df.sample(frac=1, random_state=123).reset_index(drop=True) # Shuffle the DataFrame
return df
def partition_and_save(df, sizes=(35000, 5000, 10000)):
# Shuffle the DataFrame
df_shuffled = df.sample(frac=1, random_state=123).reset_index(drop=True)
# Get indices for where to split the data
train_end = sizes[0]
val_end = sizes[0] + sizes[1]
# Split the DataFrame
train = df_shuffled.iloc[:train_end]
val = df_shuffled.iloc[train_end:val_end]
test = df_shuffled.iloc[val_end:]
# Save to CSV files
train.to_csv("train.csv", index=False)
val.to_csv("validation.csv", index=False)
test.to_csv("test.csv", index=False)
if __name__ == "__main__":
dataset_url = "http://ai.stanford.edu/~amaas/data/sentiment/aclImdb_v1.tar.gz"
print("Downloading dataset ...")
download_and_extract_dataset(dataset_url, "aclImdb_v1.tar.gz", "aclImdb")
print("Creating data frames ...")
df = load_dataset_to_dataframe()
print("Partitioning and saving data frames ...")
partition_and_save(df)

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@ -0,0 +1,99 @@
# Copyright (c) Sebastian Raschka under Apache License 2.0 (see LICENSE.txt).
# Source for "Build a Large Language Model From Scratch"
# - https://www.manning.com/books/build-a-large-language-model-from-scratch
# Code: https://github.com/rasbt/LLMs-from-scratch
import os
import requests
import json
import numpy as np
import tensorflow as tf
from tqdm import tqdm
def download_and_load_gpt2(model_size, models_dir):
# Validate model size
allowed_sizes = ("124M", "355M", "774M", "1558M")
if model_size not in allowed_sizes:
raise ValueError(f"Model size not in {allowed_sizes}")
# Define paths
model_dir = os.path.join(models_dir, model_size)
base_url = "https://openaipublic.blob.core.windows.net/gpt-2/models"
filenames = [
"checkpoint", "encoder.json", "hparams.json",
"model.ckpt.data-00000-of-00001", "model.ckpt.index",
"model.ckpt.meta", "vocab.bpe"
]
# Download files
os.makedirs(model_dir, exist_ok=True)
for filename in filenames:
file_url = os.path.join(base_url, model_size, filename)
file_path = os.path.join(model_dir, filename)
download_file(file_url, file_path)
# Load settings and params
tf_ckpt_path = tf.train.latest_checkpoint(model_dir)
settings = json.load(open(os.path.join(model_dir, "hparams.json")))
params = load_gpt2_params_from_tf_ckpt(tf_ckpt_path, settings)
return settings, params
def download_file(url, destination):
# Send a GET request to download the file in streaming mode
response = requests.get(url, stream=True)
# Get the total file size from headers, defaulting to 0 if not present
file_size = int(response.headers.get("content-length", 0))
# Check if file exists and has the same size
if os.path.exists(destination):
file_size_local = os.path.getsize(destination)
if file_size == file_size_local:
print(f"File already exists and is up-to-date: {destination}")
return
# Define the block size for reading the file
block_size = 1024 # 1 Kilobyte
# Initialize the progress bar with total file size
progress_bar_description = url.split("/")[-1] # Extract filename from URL
with tqdm(total=file_size, unit="iB", unit_scale=True, desc=progress_bar_description) as progress_bar:
# Open the destination file in binary write mode
with open(destination, "wb") as file:
# Iterate over the file data in chunks
for chunk in response.iter_content(block_size):
progress_bar.update(len(chunk)) # Update progress bar
file.write(chunk) # Write the chunk to the file
def load_gpt2_params_from_tf_ckpt(ckpt_path, settings):
# Initialize parameters dictionary with empty blocks for each layer
params = {"blocks": [{} for _ in range(settings["n_layer"])]}
# Iterate over each variable in the checkpoint
for name, _ in tf.train.list_variables(ckpt_path):
# Load the variable and remove singleton dimensions
variable_array = np.squeeze(tf.train.load_variable(ckpt_path, name))
# Process the variable name to extract relevant parts
variable_name_parts = name.split("/")[1:] # Skip the 'model/' prefix
# Identify the target dictionary for the variable
target_dict = params
if variable_name_parts[0].startswith("h"):
layer_number = int(variable_name_parts[0][1:])
target_dict = params["blocks"][layer_number]
# Recursively access or create nested dictionaries
for key in variable_name_parts[1:-1]:
target_dict = target_dict.setdefault(key, {})
# Assign the variable array to the last key
last_key = variable_name_parts[-1]
target_dict[last_key] = variable_array
return params

View File

@ -0,0 +1,321 @@
# Copyright (c) Sebastian Raschka under Apache License 2.0 (see LICENSE.txt).
# Source for "Build a Large Language Model From Scratch"
# - https://www.manning.com/books/build-a-large-language-model-from-scratch
# Code: https://github.com/rasbt/LLMs-from-scratch
#
# This file collects all the relevant code that we covered thus far
# throughout Chapters 2-5.
# This file can be run as a standalone script.
import numpy as np
import tiktoken
import torch
import torch.nn as nn
from torch.utils.data import Dataset, DataLoader
#####################################
# Chapter 2
#####################################
class GPTDatasetV1(Dataset):
def __init__(self, txt, tokenizer, max_length, stride):
self.tokenizer = tokenizer
self.input_ids = []
self.target_ids = []
# Tokenize the entire text
token_ids = tokenizer.encode(txt)
# Use a sliding window to chunk the book into overlapping sequences of max_length
for i in range(0, len(token_ids) - max_length, stride):
input_chunk = token_ids[i:i + max_length]
target_chunk = token_ids[i + 1: i + max_length + 1]
self.input_ids.append(torch.tensor(input_chunk))
self.target_ids.append(torch.tensor(target_chunk))
def __len__(self):
return len(self.input_ids)
def __getitem__(self, idx):
return self.input_ids[idx], self.target_ids[idx]
def create_dataloader_v1(txt, batch_size=4, max_length=256,
stride=128, shuffle=True, drop_last=True):
# Initialize the tokenizer
tokenizer = tiktoken.get_encoding("gpt2")
# Create dataset
dataset = GPTDatasetV1(txt, tokenizer, max_length, stride)
# Create dataloader
dataloader = DataLoader(
dataset, batch_size=batch_size, shuffle=shuffle, drop_last=drop_last)
return dataloader
#####################################
# Chapter 3
#####################################
class MultiHeadAttention(nn.Module):
def __init__(self, d_in, d_out, context_length, dropout, num_heads, qkv_bias=False):
super().__init__()
assert d_out % num_heads == 0, "d_out must be divisible by n_heads"
self.d_out = d_out
self.num_heads = num_heads
self.head_dim = d_out // num_heads # Reduce the projection dim to match desired output dim
self.W_query = nn.Linear(d_in, d_out, bias=qkv_bias)
self.W_key = nn.Linear(d_in, d_out, bias=qkv_bias)
self.W_value = nn.Linear(d_in, d_out, bias=qkv_bias)
self.out_proj = nn.Linear(d_out, d_out) # Linear layer to combine head outputs
self.dropout = nn.Dropout(dropout)
self.register_buffer('mask', torch.triu(torch.ones(context_length, context_length), diagonal=1))
def forward(self, x):
b, num_tokens, d_in = x.shape
keys = self.W_key(x) # Shape: (b, num_tokens, d_out)
queries = self.W_query(x)
values = self.W_value(x)
# We implicitly split the matrix by adding a `num_heads` dimension
# Unroll last dim: (b, num_tokens, d_out) -> (b, num_tokens, num_heads, head_dim)
keys = keys.view(b, num_tokens, self.num_heads, self.head_dim)
values = values.view(b, num_tokens, self.num_heads, self.head_dim)
queries = queries.view(b, num_tokens, self.num_heads, self.head_dim)
# Transpose: (b, num_tokens, num_heads, head_dim) -> (b, num_heads, num_tokens, head_dim)
keys = keys.transpose(1, 2)
queries = queries.transpose(1, 2)
values = values.transpose(1, 2)
# Compute scaled dot-product attention (aka self-attention) with a causal mask
attn_scores = queries @ keys.transpose(2, 3) # Dot product for each head
# Original mask truncated to the number of tokens and converted to boolean
mask_bool = self.mask.bool()[:num_tokens, :num_tokens]
# Use the mask to fill attention scores
attn_scores.masked_fill_(mask_bool, -torch.inf)
attn_weights = torch.softmax(attn_scores / keys.shape[-1]**0.5, dim=-1)
attn_weights = self.dropout(attn_weights)
# Shape: (b, num_tokens, num_heads, head_dim)
context_vec = (attn_weights @ values).transpose(1, 2)
# Combine heads, where self.d_out = self.num_heads * self.head_dim
context_vec = context_vec.reshape(b, num_tokens, self.d_out)
context_vec = self.out_proj(context_vec) # optional projection
return context_vec
#####################################
# Chapter 4
#####################################
class LayerNorm(nn.Module):
def __init__(self, emb_dim):
super().__init__()
self.eps = 1e-5
self.scale = nn.Parameter(torch.ones(emb_dim))
self.shift = nn.Parameter(torch.zeros(emb_dim))
def forward(self, x):
mean = x.mean(dim=-1, keepdim=True)
var = x.var(dim=-1, keepdim=True, unbiased=False)
norm_x = (x - mean) / torch.sqrt(var + self.eps)
return self.scale * norm_x + self.shift
class GELU(nn.Module):
def __init__(self):
super().__init__()
def forward(self, x):
return 0.5 * x * (1 + torch.tanh(
torch.sqrt(torch.tensor(2.0 / torch.pi)) *
(x + 0.044715 * torch.pow(x, 3))
))
class FeedForward(nn.Module):
def __init__(self, cfg):
super().__init__()
self.layers = nn.Sequential(
nn.Linear(cfg["emb_dim"], 4 * cfg["emb_dim"]),
GELU(),
nn.Linear(4 * cfg["emb_dim"], cfg["emb_dim"]),
)
def forward(self, x):
return self.layers(x)
class TransformerBlock(nn.Module):
def __init__(self, cfg):
super().__init__()
self.att = MultiHeadAttention(
d_in=cfg["emb_dim"],
d_out=cfg["emb_dim"],
context_length=cfg["context_length"],
num_heads=cfg["n_heads"],
dropout=cfg["drop_rate"],
qkv_bias=cfg["qkv_bias"])
self.ff = FeedForward(cfg)
self.norm1 = LayerNorm(cfg["emb_dim"])
self.norm2 = LayerNorm(cfg["emb_dim"])
self.drop_resid = nn.Dropout(cfg["drop_rate"])
def forward(self, x):
# Shortcut connection for attention block
shortcut = x
x = self.norm1(x)
x = self.att(x) # Shape [batch_size, num_tokens, emb_size]
x = self.drop_resid(x)
x = x + shortcut # Add the original input back
# Shortcut connection for feed-forward block
shortcut = x
x = self.norm2(x)
x = self.ff(x)
x = self.drop_resid(x)
x = x + shortcut # Add the original input back
return x
class GPTModel(nn.Module):
def __init__(self, cfg):
super().__init__()
self.tok_emb = nn.Embedding(cfg["vocab_size"], cfg["emb_dim"])
self.pos_emb = nn.Embedding(cfg["context_length"], cfg["emb_dim"])
self.drop_emb = nn.Dropout(cfg["drop_rate"])
self.trf_blocks = nn.Sequential(
*[TransformerBlock(cfg) for _ in range(cfg["n_layers"])])
self.final_norm = LayerNorm(cfg["emb_dim"])
self.out_head = nn.Linear(cfg["emb_dim"], cfg["vocab_size"], bias=False)
def forward(self, in_idx):
batch_size, seq_len = in_idx.shape
tok_embeds = self.tok_emb(in_idx)
pos_embeds = self.pos_emb(torch.arange(seq_len, device=in_idx.device))
x = tok_embeds + pos_embeds # Shape [batch_size, num_tokens, emb_size]
x = self.drop_emb(x)
x = self.trf_blocks(x)
x = self.final_norm(x)
logits = self.out_head(x)
return logits
def generate_text_simple(model, idx, max_new_tokens, context_size):
# idx is (B, T) array of indices in the current context
for _ in range(max_new_tokens):
# Crop current context if it exceeds the supported context size
# E.g., if LLM supports only 5 tokens, and the context size is 10
# then only the last 5 tokens are used as context
idx_cond = idx[:, -context_size:]
# Get the predictions
with torch.no_grad():
logits = model(idx_cond)
# Focus only on the last time step
# (batch, n_token, vocab_size) becomes (batch, vocab_size)
logits = logits[:, -1, :]
# Get the idx of the vocab entry with the highest logits value
idx_next = torch.argmax(logits, dim=-1, keepdim=True) # (batch, 1)
# Append sampled index to the running sequence
idx = torch.cat((idx, idx_next), dim=1) # (batch, n_tokens+1)
return idx
#####################################
# Chapter 5
#####################################
def assign(left, right):
if left.shape != right.shape:
raise ValueError(f"Shape mismatch. Left: {left.shape}, Right: {right.shape}")
return torch.nn.Parameter(torch.tensor(right))
def load_weights_into_gpt(gpt, params):
gpt.pos_emb.weight = assign(gpt.pos_emb.weight, params['wpe'])
gpt.tok_emb.weight = assign(gpt.tok_emb.weight, params['wte'])
for b in range(len(params["blocks"])):
q_w, k_w, v_w = np.split(
(params["blocks"][b]["attn"]["c_attn"])["w"], 3, axis=-1)
gpt.trf_blocks[b].att.W_query.weight = assign(
gpt.trf_blocks[b].att.W_query.weight, q_w.T)
gpt.trf_blocks[b].att.W_key.weight = assign(
gpt.trf_blocks[b].att.W_key.weight, k_w.T)
gpt.trf_blocks[b].att.W_value.weight = assign(
gpt.trf_blocks[b].att.W_value.weight, v_w.T)
q_b, k_b, v_b = np.split(
(params["blocks"][b]["attn"]["c_attn"])["b"], 3, axis=-1)
gpt.trf_blocks[b].att.W_query.bias = assign(
gpt.trf_blocks[b].att.W_query.bias, q_b)
gpt.trf_blocks[b].att.W_key.bias = assign(
gpt.trf_blocks[b].att.W_key.bias, k_b)
gpt.trf_blocks[b].att.W_value.bias = assign(
gpt.trf_blocks[b].att.W_value.bias, v_b)
gpt.trf_blocks[b].att.out_proj.weight = assign(
gpt.trf_blocks[b].att.out_proj.weight,
params["blocks"][b]["attn"]["c_proj"]["w"].T)
gpt.trf_blocks[b].att.out_proj.bias = assign(
gpt.trf_blocks[b].att.out_proj.bias,
params["blocks"][b]["attn"]["c_proj"]["b"])
gpt.trf_blocks[b].ff.layers[0].weight = assign(
gpt.trf_blocks[b].ff.layers[0].weight,
params["blocks"][b]["mlp"]["c_fc"]["w"].T)
gpt.trf_blocks[b].ff.layers[0].bias = assign(
gpt.trf_blocks[b].ff.layers[0].bias,
params["blocks"][b]["mlp"]["c_fc"]["b"])
gpt.trf_blocks[b].ff.layers[2].weight = assign(
gpt.trf_blocks[b].ff.layers[2].weight,
params["blocks"][b]["mlp"]["c_proj"]["w"].T)
gpt.trf_blocks[b].ff.layers[2].bias = assign(
gpt.trf_blocks[b].ff.layers[2].bias,
params["blocks"][b]["mlp"]["c_proj"]["b"])
gpt.trf_blocks[b].norm1.scale = assign(
gpt.trf_blocks[b].norm1.scale,
params["blocks"][b]["ln_1"]["g"])
gpt.trf_blocks[b].norm1.shift = assign(
gpt.trf_blocks[b].norm1.shift,
params["blocks"][b]["ln_1"]["b"])
gpt.trf_blocks[b].norm2.scale = assign(
gpt.trf_blocks[b].norm2.scale,
params["blocks"][b]["ln_2"]["g"])
gpt.trf_blocks[b].norm2.shift = assign(
gpt.trf_blocks[b].norm2.shift,
params["blocks"][b]["ln_2"]["b"])
gpt.final_norm.scale = assign(gpt.final_norm.scale, params["g"])
gpt.final_norm.shift = assign(gpt.final_norm.shift, params["b"])
gpt.out_head.weight = assign(gpt.out_head.weight, params["wte"])
def text_to_token_ids(text, tokenizer):
encoded = tokenizer.encode(text, allowed_special={'<|endoftext|>'})
encoded_tensor = torch.tensor(encoded).unsqueeze(0) # add batch dimension
return encoded_tensor
def token_ids_to_text(token_ids, tokenizer):
flat = token_ids.squeeze(0) # remove batch dimension
return tokenizer.decode(flat.tolist())

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transformers>=4.33.2
scikit-learn>=1.3.0

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{
"cells": [
{
"cell_type": "markdown",
"id": "8968a681-2db1-4840-bb73-7d6c95986825",
"metadata": {},
"source": [
"<table style=\"width:100%\">\n",
"<tr>\n",
"<td style=\"vertical-align:middle; text-align:left;\">\n",
"<font size=\"2\">\n",
"Supplementary code for the <a href=\"http://mng.bz/orYv\">Build a Large Language Model From Scratch</a> book by <a href=\"https://sebastianraschka.com\">Sebastian Raschka</a><br>\n",
"<br>Code repository: <a href=\"https://github.com/rasbt/LLMs-from-scratch\">https://github.com/rasbt/LLMs-from-scratch</a>\n",
"</font>\n",
"</td>\n",
"<td style=\"vertical-align:middle; text-align:left;\">\n",
"<a href=\"http://mng.bz/orYv\"><img src=\"https://sebastianraschka.com/images/LLMs-from-scratch-images/cover-small.webp\" width=\"100px\"></a>\n",
"</td>\n",
"</tr>\n",
"</table>"
]
},
{
"cell_type": "markdown",
"id": "8b6e1cdd-b14e-4368-bdbb-9bf7ab821791",
"metadata": {},
"source": [
"# Scikit-learn Logistic 回归模型"
]
},
{
"cell_type": "code",
"execution_count": 1,
"id": "c2a72242-6197-4bef-aa05-696a152350d5",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"100% | 80.23 MB | 4.37 MB/s | 18.38 sec elapsed"
]
}
],
"source": [
"!python download-prepare-dataset.py"
]
},
{
"cell_type": "code",
"execution_count": 14,
"id": "69f32433-e19c-4066-b806-8f30b408107f",
"metadata": {},
"outputs": [],
"source": [
"import pandas as pd\n",
"\n",
"train_df = pd.read_csv(\"train.csv\")\n",
"val_df = pd.read_csv(\"validation.csv\")\n",
"test_df = pd.read_csv(\"test.csv\")"
]
},
{
"cell_type": "code",
"execution_count": 16,
"id": "0808b212-fe91-48d9-80b8-55519f8835d5",
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"<div>\n",
"<style scoped>\n",
" .dataframe tbody tr th:only-of-type {\n",
" vertical-align: middle;\n",
" }\n",
"\n",
" .dataframe tbody tr th {\n",
" vertical-align: top;\n",
" }\n",
"\n",
" .dataframe thead th {\n",
" text-align: right;\n",
" }\n",
"</style>\n",
"<table border=\"1\" class=\"dataframe\">\n",
" <thead>\n",
" <tr style=\"text-align: right;\">\n",
" <th></th>\n",
" <th>text</th>\n",
" <th>label</th>\n",
" </tr>\n",
" </thead>\n",
" <tbody>\n",
" <tr>\n",
" <th>0</th>\n",
" <td>The only reason I saw \"Shakedown\" was that it ...</td>\n",
" <td>0</td>\n",
" </tr>\n",
" <tr>\n",
" <th>1</th>\n",
" <td>This is absolute drivel, designed to shock and...</td>\n",
" <td>0</td>\n",
" </tr>\n",
" <tr>\n",
" <th>2</th>\n",
" <td>Lots of scenes and dialogue are flat-out goofy...</td>\n",
" <td>1</td>\n",
" </tr>\n",
" <tr>\n",
" <th>3</th>\n",
" <td>** and 1/2 stars out of **** Lifeforce is one ...</td>\n",
" <td>1</td>\n",
" </tr>\n",
" <tr>\n",
" <th>4</th>\n",
" <td>I learned a thing: you have to take this film ...</td>\n",
" <td>1</td>\n",
" </tr>\n",
" </tbody>\n",
"</table>\n",
"</div>"
],
"text/plain": [
" text label\n",
"0 The only reason I saw \"Shakedown\" was that it ... 0\n",
"1 This is absolute drivel, designed to shock and... 0\n",
"2 Lots of scenes and dialogue are flat-out goofy... 1\n",
"3 ** and 1/2 stars out of **** Lifeforce is one ... 1\n",
"4 I learned a thing: you have to take this film ... 1"
]
},
"execution_count": 16,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"train_df.head()"
]
},
{
"cell_type": "markdown",
"id": "fae87bc1-14ca-4f89-8e12-49f77b0ec00d",
"metadata": {},
"source": [
"## Scikit-learn baseline"
]
},
{
"cell_type": "code",
"execution_count": 17,
"id": "180318b7-de18-4b05-b84a-ba97c72b9d8e",
"metadata": {},
"outputs": [],
"source": [
"from sklearn.feature_extraction.text import CountVectorizer\n",
"from sklearn.linear_model import LogisticRegression\n",
"from sklearn.metrics import accuracy_score"
]
},
{
"cell_type": "code",
"execution_count": 20,
"id": "25090b7c-f516-4be2-8083-3a7187fe4635",
"metadata": {},
"outputs": [],
"source": [
"vectorizer = CountVectorizer()\n",
"\n",
"X_train = vectorizer.fit_transform(train_df[\"text\"])\n",
"X_val = vectorizer.transform(val_df[\"text\"])\n",
"X_test = vectorizer.transform(test_df[\"text\"])\n",
"\n",
"y_train, y_val, y_test = train_df[\"label\"], val_df[\"label\"], test_df[\"label\"]"
]
},
{
"cell_type": "code",
"execution_count": 22,
"id": "0247de3a-88f0-4b9c-becd-157baf3acf49",
"metadata": {},
"outputs": [],
"source": [
"def eval(model, X_train, y_train, X_val, y_val, X_test, y_test):\n",
" # Making predictions\n",
" y_pred_train = model.predict(X_train)\n",
" y_pred_val = model.predict(X_val)\n",
" y_pred_test = model.predict(X_test)\n",
" \n",
" # Calculating accuracy and balanced accuracy\n",
" accuracy_train = accuracy_score(y_train, y_pred_train)\n",
" balanced_accuracy_train = balanced_accuracy_score(y_train, y_pred_train)\n",
" \n",
" accuracy_val = accuracy_score(y_val, y_pred_val)\n",
" balanced_accuracy_val = balanced_accuracy_score(y_val, y_pred_val)\n",
"\n",
" accuracy_test = accuracy_score(y_test, y_pred_test)\n",
" balanced_accuracy_test = balanced_accuracy_score(y_test, y_pred_test)\n",
" \n",
" # Printing the results\n",
" print(f\"Training Accuracy: {accuracy_train*100:.2f}%\")\n",
" print(f\"Validation Accuracy: {accuracy_val*100:.2f}%\")\n",
" print(f\"Test Accuracy: {accuracy_test*100:.2f}%\")"
]
},
{
"cell_type": "code",
"execution_count": 23,
"id": "c29c6dfc-f72d-40ab-8cb5-783aad1a15ab",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Training Accuracy: 50.01%\n",
"Validation Accuracy: 50.14%\n",
"Test Accuracy: 49.91%\n"
]
}
],
"source": [
"from sklearn.dummy import DummyClassifier\n",
"\n",
"# Create a dummy classifier with the strategy to predict the most frequent class\n",
"dummy_clf = DummyClassifier(strategy=\"most_frequent\")\n",
"dummy_clf.fit(X_train, y_train)\n",
"\n",
"eval(dummy_clf, X_train, y_train, X_val, y_val, X_test, y_test)"
]
},
{
"cell_type": "code",
"execution_count": 24,
"id": "088a8a3a-3b74-4d10-a51b-cb662569ae39",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Training Accuracy: 99.80%\n",
"Validation Accuracy: 88.62%\n",
"Test Accuracy: 88.85%\n"
]
}
],
"source": [
"model = LogisticRegression(max_iter=1000)\n",
"model.fit(X_train, y_train)\n",
"eval(model, X_train, y_train, X_val, y_val, X_test, y_test)"
]
}
],
"metadata": {
"kernelspec": {
"display_name": "Python 3 (ipykernel)",
"language": "python",
"name": "python3"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 3
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
"version": "3.11.4"
}
},
"nbformat": 4,
"nbformat_minor": 5
}

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# Copyright (c) Sebastian Raschka under Apache License 2.0 (see LICENSE.txt).
# Source for "Build a Large Language Model From Scratch"
# - https://www.manning.com/books/build-a-large-language-model-from-scratch
# Code: https://github.com/rasbt/LLMs-from-scratch
import argparse
from pathlib import Path
import time
import pandas as pd
import torch
from torch.utils.data import DataLoader
from torch.utils.data import Dataset
from transformers import AutoTokenizer, AutoModelForSequenceClassification
class IMDBDataset(Dataset):
def __init__(self, csv_file, tokenizer, max_length=None, pad_token_id=50256):
self.data = pd.read_csv(csv_file)
self.max_length = max_length if max_length is not None else self._longest_encoded_length(tokenizer)
# Pre-tokenize texts
self.encoded_texts = [
tokenizer.encode(text)[:self.max_length]
for text in self.data["text"]
]
# Pad sequences to the longest sequence
# Debug
pad_token_id = 0
self.encoded_texts = [
et + [pad_token_id] * (self.max_length - len(et))
for et in self.encoded_texts
]
def __getitem__(self, index):
encoded = self.encoded_texts[index]
label = self.data.iloc[index]["label"]
return torch.tensor(encoded, dtype=torch.long), torch.tensor(label, dtype=torch.long)
def __len__(self):
return len(self.data)
def _longest_encoded_length(self, tokenizer):
max_length = 0
for text in self.data["text"]:
encoded_length = len(tokenizer.encode(text))
if encoded_length > max_length:
max_length = encoded_length
return max_length
def calc_loss_batch(input_batch, target_batch, model, device):
input_batch, target_batch = input_batch.to(device), target_batch.to(device)
# logits = model(input_batch)[:, -1, :] # Logits of last output token
logits = model(input_batch).logits
loss = torch.nn.functional.cross_entropy(logits, target_batch)
return loss
# Same as in chapter 5
def calc_loss_loader(data_loader, model, device, num_batches=None):
total_loss = 0.
if num_batches is None:
num_batches = len(data_loader)
else:
# Reduce the number of batches to match the total number of batches in the data loader
# if num_batches exceeds the number of batches in the data loader
num_batches = min(num_batches, len(data_loader))
for i, (input_batch, target_batch) in enumerate(data_loader):
if i < num_batches:
loss = calc_loss_batch(input_batch, target_batch, model, device)
total_loss += loss.item()
else:
break
return total_loss / num_batches
@torch.no_grad() # Disable gradient tracking for efficiency
def calc_accuracy_loader(data_loader, model, device, num_batches=None):
model.eval()
correct_predictions, num_examples = 0, 0
if num_batches is None:
num_batches = len(data_loader)
else:
num_batches = min(num_batches, len(data_loader))
for i, (input_batch, target_batch) in enumerate(data_loader):
if i < num_batches:
input_batch, target_batch = input_batch.to(device), target_batch.to(device)
# logits = model(input_batch)[:, -1, :] # Logits of last output token
logits = model(input_batch).logits
predicted_labels = torch.argmax(logits, dim=1)
num_examples += predicted_labels.shape[0]
correct_predictions += (predicted_labels == target_batch).sum().item()
else:
break
return correct_predictions / num_examples
def evaluate_model(model, train_loader, val_loader, device, eval_iter):
model.eval()
with torch.no_grad():
train_loss = calc_loss_loader(train_loader, model, device, num_batches=eval_iter)
val_loss = calc_loss_loader(val_loader, model, device, num_batches=eval_iter)
model.train()
return train_loss, val_loss
def train_classifier_simple(model, train_loader, val_loader, optimizer, device, num_epochs,
eval_freq, eval_iter, tokenizer, max_steps=None):
# Initialize lists to track losses and tokens seen
train_losses, val_losses, train_accs, val_accs = [], [], [], []
examples_seen, global_step = 0, -1
# Main training loop
for epoch in range(num_epochs):
model.train() # Set model to training mode
for input_batch, target_batch in train_loader:
optimizer.zero_grad() # Reset loss gradients from previous epoch
loss = calc_loss_batch(input_batch, target_batch, model, device)
loss.backward() # Calculate loss gradients
optimizer.step() # Update model weights using loss gradients
examples_seen += input_batch.shape[0] # New: track examples instead of tokens
global_step += 1
# Optional evaluation step
if global_step % eval_freq == 0:
train_loss, val_loss = evaluate_model(
model, train_loader, val_loader, device, eval_iter)
train_losses.append(train_loss)
val_losses.append(val_loss)
print(f"Ep {epoch+1} (Step {global_step:06d}): "
f"Train loss {train_loss:.3f}, Val loss {val_loss:.3f}")
if max_steps is not None and global_step > max_steps:
break
# New: Calculate accuracy after each epoch
train_accuracy = calc_accuracy_loader(train_loader, model, device, num_batches=eval_iter)
val_accuracy = calc_accuracy_loader(val_loader, model, device, num_batches=eval_iter)
print(f"Training accuracy: {train_accuracy*100:.2f}% | ", end="")
print(f"Validation accuracy: {val_accuracy*100:.2f}%")
train_accs.append(train_accuracy)
val_accs.append(val_accuracy)
if max_steps is not None and global_step > max_steps:
break
return train_losses, val_losses, train_accs, val_accs, examples_seen
if __name__ == "__main__":
parser = argparse.ArgumentParser()
parser.add_argument(
"--trainable_layers",
type=str,
default="last_block",
help=(
"Which layers to train. Options: 'all', 'last_block', 'last_layer'."
)
)
parser.add_argument(
"--bert_model",
type=str,
default="distilbert",
help=(
"Which layers to train. Options: 'all', 'last_block', 'last_layer'."
)
)
args = parser.parse_args()
###############################
# Load model
###############################
torch.manual_seed(123)
if args.bert_model == "distilbert":
model = AutoModelForSequenceClassification.from_pretrained(
"distilbert-base-uncased", num_labels=2
)
model.out_head = torch.nn.Linear(in_features=768, out_features=2)
if args.trainable_layers == "last_layer":
pass
elif args.trainable_layers == "last_block":
for param in model.pre_classifier.parameters():
param.requires_grad = True
for param in model.distilbert.transformer.layer[-1].parameters():
param.requires_grad = True
elif args.trainable_layers == "all":
for param in model.parameters():
param.requires_grad = True
else:
raise ValueError("Invalid --trainable_layers argument.")
tokenizer = AutoTokenizer.from_pretrained("distilbert-base-uncased")
elif args.bert_model == "roberta":
model = AutoModelForSequenceClassification.from_pretrained(
"FacebookAI/roberta-large", num_labels=2
)
model.classifier.out_proj = torch.nn.Linear(in_features=1024, out_features=2)
if args.trainable_layers == "last_layer":
pass
elif args.trainable_layers == "last_block":
for param in model.classifier.parameters():
param.requires_grad = True
for param in model.roberta.encoder.layer[-1].parameters():
param.requires_grad = True
elif args.trainable_layers == "all":
for param in model.parameters():
param.requires_grad = True
else:
raise ValueError("Invalid --trainable_layers argument.")
tokenizer = AutoTokenizer.from_pretrained("FacebookAI/roberta-large")
else:
raise ValueError("Selected --bert_model not supported.")
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
model.to(device)
model.eval()
###############################
# Instantiate dataloaders
###############################
pad_token_id = tokenizer.encode(tokenizer.pad_token)
base_path = Path(".")
train_dataset = IMDBDataset(base_path / "train.csv", max_length=256, tokenizer=tokenizer, pad_token_id=pad_token_id)
val_dataset = IMDBDataset(base_path / "validation.csv", max_length=256, tokenizer=tokenizer, pad_token_id=pad_token_id)
test_dataset = IMDBDataset(base_path / "test.csv", max_length=256, tokenizer=tokenizer, pad_token_id=pad_token_id)
num_workers = 0
batch_size = 8
train_loader = DataLoader(
dataset=train_dataset,
batch_size=batch_size,
shuffle=True,
num_workers=num_workers,
drop_last=True,
)
val_loader = DataLoader(
dataset=val_dataset,
batch_size=batch_size,
num_workers=num_workers,
drop_last=False,
)
test_loader = DataLoader(
dataset=test_dataset,
batch_size=batch_size,
num_workers=num_workers,
drop_last=False,
)
###############################
# Train model
###############################
start_time = time.time()
torch.manual_seed(123)
optimizer = torch.optim.AdamW(model.parameters(), lr=5e-5, weight_decay=0.1)
num_epochs = 3
train_losses, val_losses, train_accs, val_accs, examples_seen = train_classifier_simple(
model, train_loader, val_loader, optimizer, device,
num_epochs=num_epochs, eval_freq=50, eval_iter=20,
tokenizer=tokenizer, max_steps=None
)
end_time = time.time()
execution_time_minutes = (end_time - start_time) / 60
print(f"Training completed in {execution_time_minutes:.2f} minutes.")
###############################
# Evaluate model
###############################
print("\nEvaluating on the full datasets ...\n")
train_accuracy = calc_accuracy_loader(train_loader, model, device)
val_accuracy = calc_accuracy_loader(val_loader, model, device)
test_accuracy = calc_accuracy_loader(test_loader, model, device)
print(f"Training accuracy: {train_accuracy*100:.2f}%")
print(f"Validation accuracy: {val_accuracy*100:.2f}%")
print(f"Test accuracy: {test_accuracy*100:.2f}%")

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# Copyright (c) Sebastian Raschka under Apache License 2.0 (see LICENSE.txt).
# Source for "Build a Large Language Model From Scratch"
# - https://www.manning.com/books/build-a-large-language-model-from-scratch
# Code: https://github.com/rasbt/LLMs-from-scratch
import argparse
from pathlib import Path
import time
import pandas as pd
import tiktoken
import torch
from torch.utils.data import DataLoader
from torch.utils.data import Dataset
from gpt_download import download_and_load_gpt2
from previous_chapters import GPTModel, load_weights_into_gpt
class IMDBDataset(Dataset):
def __init__(self, csv_file, tokenizer, max_length=None, pad_token_id=50256):
self.data = pd.read_csv(csv_file)
self.max_length = max_length if max_length is not None else self._longest_encoded_length(tokenizer)
# Pre-tokenize texts
self.encoded_texts = [
tokenizer.encode(text)[:self.max_length]
for text in self.data["text"]
]
# Pad sequences to the longest sequence
self.encoded_texts = [
et + [pad_token_id] * (self.max_length - len(et))
for et in self.encoded_texts
]
def __getitem__(self, index):
encoded = self.encoded_texts[index]
label = self.data.iloc[index]["label"]
return torch.tensor(encoded, dtype=torch.long), torch.tensor(label, dtype=torch.long)
def __len__(self):
return len(self.data)
def _longest_encoded_length(self, tokenizer):
max_length = 0
for text in self.data["text"]:
encoded_length = len(tokenizer.encode(text))
if encoded_length > max_length:
max_length = encoded_length
return max_length
def instantiate_model(choose_model, load_weights):
BASE_CONFIG = {
"vocab_size": 50257, # Vocabulary size
"context_length": 1024, # Context length
"drop_rate": 0.0, # Dropout rate
"qkv_bias": True # Query-key-value bias
}
model_configs = {
"gpt2-small (124M)": {"emb_dim": 768, "n_layers": 12, "n_heads": 12},
"gpt2-medium (355M)": {"emb_dim": 1024, "n_layers": 24, "n_heads": 16},
"gpt2-large (774M)": {"emb_dim": 1280, "n_layers": 36, "n_heads": 20},
"gpt2-xl (1558M)": {"emb_dim": 1600, "n_layers": 48, "n_heads": 25},
}
BASE_CONFIG.update(model_configs[choose_model])
if not load_weights:
torch.manual_seed(123)
model = GPTModel(BASE_CONFIG)
if load_weights:
model_size = choose_model.split(" ")[-1].lstrip("(").rstrip(")")
settings, params = download_and_load_gpt2(model_size=model_size, models_dir="gpt2")
load_weights_into_gpt(model, params)
model.eval()
return model
def calc_loss_batch(input_batch, target_batch, model, device, trainable_token=-1):
input_batch, target_batch = input_batch.to(device), target_batch.to(device)
logits = model(input_batch)[:, trainable_token, :] # Logits of last output token
loss = torch.nn.functional.cross_entropy(logits, target_batch)
return loss
def calc_loss_loader(data_loader, model, device, num_batches=None, trainable_token=-1):
total_loss = 0.
if len(data_loader) == 0:
return float("nan")
elif num_batches is None:
num_batches = len(data_loader)
else:
# Reduce the number of batches to match the total number of batches in the data loader
# if num_batches exceeds the number of batches in the data loader
num_batches = min(num_batches, len(data_loader))
for i, (input_batch, target_batch) in enumerate(data_loader):
if i < num_batches:
loss = calc_loss_batch(input_batch, target_batch, model, device, trainable_token=trainable_token)
total_loss += loss.item()
else:
break
return total_loss / num_batches
@torch.no_grad() # Disable gradient tracking for efficiency
def calc_accuracy_loader(data_loader, model, device, num_batches=None, trainable_token=-1):
model.eval()
correct_predictions, num_examples = 0, 0
if num_batches is None:
num_batches = len(data_loader)
else:
num_batches = min(num_batches, len(data_loader))
for i, (input_batch, target_batch) in enumerate(data_loader):
if i < num_batches:
input_batch, target_batch = input_batch.to(device), target_batch.to(device)
logits = model(input_batch)[:, trainable_token, :] # Logits of last output token
predicted_labels = torch.argmax(logits, dim=-1)
num_examples += predicted_labels.shape[0]
correct_predictions += (predicted_labels == target_batch).sum().item()
else:
break
return correct_predictions / num_examples
def evaluate_model(model, train_loader, val_loader, device, eval_iter, trainable_token=-1):
model.eval()
with torch.no_grad():
train_loss = calc_loss_loader(train_loader, model, device, num_batches=eval_iter, trainable_token=trainable_token)
val_loss = calc_loss_loader(val_loader, model, device, num_batches=eval_iter, trainable_token=trainable_token)
model.train()
return train_loss, val_loss
def train_classifier_simple(model, train_loader, val_loader, optimizer, device, num_epochs,
eval_freq, eval_iter, tokenizer, max_steps=None, trainable_token=-1):
# Initialize lists to track losses and tokens seen
train_losses, val_losses, train_accs, val_accs = [], [], [], []
examples_seen, global_step = 0, -1
# Main training loop
for epoch in range(num_epochs):
model.train() # Set model to training mode
for input_batch, target_batch in train_loader:
optimizer.zero_grad() # Reset loss gradients from previous epoch
loss = calc_loss_batch(input_batch, target_batch, model, device, trainable_token=trainable_token)
loss.backward() # Calculate loss gradients
optimizer.step() # Update model weights using loss gradients
examples_seen += input_batch.shape[0] # New: track examples instead of tokens
global_step += 1
# Optional evaluation step
if global_step % eval_freq == 0:
train_loss, val_loss = evaluate_model(
model, train_loader, val_loader, device, eval_iter, trainable_token=trainable_token)
train_losses.append(train_loss)
val_losses.append(val_loss)
print(f"Ep {epoch+1} (Step {global_step:06d}): "
f"Train loss {train_loss:.3f}, Val loss {val_loss:.3f}")
if max_steps is not None and global_step > max_steps:
break
# New: Calculate accuracy after each epoch
train_accuracy = calc_accuracy_loader(train_loader, model, device, num_batches=eval_iter, trainable_token=trainable_token)
val_accuracy = calc_accuracy_loader(val_loader, model, device, num_batches=eval_iter, trainable_token=trainable_token)
print(f"Training accuracy: {train_accuracy*100:.2f}% | ", end="")
print(f"Validation accuracy: {val_accuracy*100:.2f}%")
train_accs.append(train_accuracy)
val_accs.append(val_accuracy)
if max_steps is not None and global_step > max_steps:
break
return train_losses, val_losses, train_accs, val_accs, examples_seen
if __name__ == "__main__":
parser = argparse.ArgumentParser()
parser.add_argument(
"--model_size",
type=str,
default="gpt2-small (124M)",
help=(
"Which GPT model to use. Options: 'gpt2-small (124M)', 'gpt2-medium (355M)',"
" 'gpt2-large (774M)', 'gpt2-xl (1558M)'."
)
)
parser.add_argument(
"--weights",
type=str,
default="pretrained",
help=(
"Whether to use 'pretrained' or 'random' weights."
)
)
parser.add_argument(
"--trainable_layers",
type=str,
default="last_block",
help=(
"Which layers to train. Options: 'all', 'last_block', 'last_layer'."
)
)
parser.add_argument(
"--trainable_token",
type=str,
default="last",
help=(
"Which token to train. Options: 'first', 'last'."
)
)
parser.add_argument(
"--context_length",
type=str,
default="256",
help=(
"The context length of the data inputs."
"Options: 'longest_training_example', 'model_context_length' or integer value."
)
)
args = parser.parse_args()
if args.trainable_token == "first":
args.trainable_token = 0
elif args.trainable_token == "last":
args.trainable_token = -1
else:
raise ValueError("Invalid --trainable_token argument")
###############################
# Load model
###############################
if args.weights == "pretrained":
load_weights = True
elif args.weights == "random":
load_weights = False
else:
raise ValueError("Invalid --weights argument.")
model = instantiate_model(args.model_size, load_weights)
for param in model.parameters():
param.requires_grad = False
if args.model_size == "gpt2-small (124M)":
in_features = 768
elif args.model_size == "gpt2-medium (355M)":
in_features = 1024
elif args.model_size == "gpt2-large (774M)":
in_features = 1280
elif args.model_size == "gpt2-xl (1558M)":
in_features = 1600
else:
raise ValueError("Invalid --model_size argument")
torch.manual_seed(123)
model.out_head = torch.nn.Linear(in_features=in_features, out_features=2)
if args.trainable_layers == "last_layer":
pass
elif args.trainable_layers == "last_block":
for param in model.trf_blocks[-1].parameters():
param.requires_grad = True
for param in model.final_norm.parameters():
param.requires_grad = True
elif args.trainable_layers == "all":
for param in model.parameters():
param.requires_grad = True
else:
raise ValueError("Invalid --trainable_layers argument.")
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
model.to(device)
###############################
# Instantiate dataloaders
###############################
base_path = Path(".")
tokenizer = tiktoken.get_encoding("gpt2")
train_dataset = None
if args.context_length == "model_context_length":
max_length = model.pos_emb.weight.shape[0]
elif args.context_length == "longest_training_example":
train_dataset = IMDBDataset(base_path / "train.csv", max_length=None, tokenizer=tokenizer)
max_length = train_dataset.max_length
else:
try:
max_length = int(args.context_length)
except ValueError:
raise ValueError("Invalid --context_length argument")
if train_dataset is None:
train_dataset = IMDBDataset(base_path / "train.csv", max_length=max_length, tokenizer=tokenizer)
val_dataset = IMDBDataset(base_path / "validation.csv", max_length=max_length, tokenizer=tokenizer)
test_dataset = IMDBDataset(base_path / "test.csv", max_length=max_length, tokenizer=tokenizer)
num_workers = 0
batch_size = 8
train_loader = DataLoader(
dataset=train_dataset,
batch_size=batch_size,
shuffle=True,
num_workers=num_workers,
drop_last=True,
)
val_loader = DataLoader(
dataset=val_dataset,
batch_size=batch_size,
num_workers=num_workers,
drop_last=False,
)
test_loader = DataLoader(
dataset=test_dataset,
batch_size=batch_size,
num_workers=num_workers,
drop_last=False,
)
###############################
# Train model
###############################
start_time = time.time()
torch.manual_seed(123)
optimizer = torch.optim.AdamW(model.parameters(), lr=5e-5, weight_decay=0.1)
num_epochs = 3
train_losses, val_losses, train_accs, val_accs, examples_seen = train_classifier_simple(
model, train_loader, val_loader, optimizer, device,
num_epochs=num_epochs, eval_freq=50, eval_iter=20,
tokenizer=tokenizer, max_steps=None, trainable_token=args.trainable_token
)
end_time = time.time()
execution_time_minutes = (end_time - start_time) / 60
print(f"Training completed in {execution_time_minutes:.2f} minutes.")
###############################
# Evaluate model
###############################
print("\nEvaluating on the full datasets ...\n")
train_accuracy = calc_accuracy_loader(train_loader, model, device, trainable_token=args.trainable_token)
val_accuracy = calc_accuracy_loader(val_loader, model, device, trainable_token=args.trainable_token)
test_accuracy = calc_accuracy_loader(test_loader, model, device, trainable_token=args.trainable_token)
print(f"Training accuracy: {train_accuracy*100:.2f}%")
print(f"Validation accuracy: {val_accuracy*100:.2f}%")
print(f"Test accuracy: {test_accuracy*100:.2f}%")

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# Copyright (c) Sebastian Raschka under Apache License 2.0 (see LICENSE.txt).
# Source for "Build a Large Language Model From Scratch"
# - https://www.manning.com/books/build-a-large-language-model-from-scratch
# Code: https://github.com/rasbt/LLMs-from-scratch
import pandas as pd
from sklearn.feature_extraction.text import CountVectorizer
from sklearn.linear_model import LogisticRegression
from sklearn.metrics import accuracy_score
# from sklearn.metrics import balanced_accuracy_score
from sklearn.dummy import DummyClassifier
def load_dataframes():
df_train = pd.read_csv("train.csv")
df_val = pd.read_csv("validation.csv")
df_test = pd.read_csv("test.csv")
return df_train, df_val, df_test
def eval(model, X_train, y_train, X_val, y_val, X_test, y_test):
# Making predictions
y_pred_train = model.predict(X_train)
y_pred_val = model.predict(X_val)
y_pred_test = model.predict(X_test)
# Calculating accuracy and balanced accuracy
accuracy_train = accuracy_score(y_train, y_pred_train)
# balanced_accuracy_train = balanced_accuracy_score(y_train, y_pred_train)
accuracy_val = accuracy_score(y_val, y_pred_val)
# balanced_accuracy_val = balanced_accuracy_score(y_val, y_pred_val)
accuracy_test = accuracy_score(y_test, y_pred_test)
# balanced_accuracy_test = balanced_accuracy_score(y_test, y_pred_test)
# Printing the results
print(f"Training Accuracy: {accuracy_train*100:.2f}%")
print(f"Validation Accuracy: {accuracy_val*100:.2f}%")
print(f"Test Accuracy: {accuracy_test*100:.2f}%")
# print(f"\nTraining Balanced Accuracy: {balanced_accuracy_train*100:.2f}%")
# print(f"Validation Balanced Accuracy: {balanced_accuracy_val*100:.2f}%")
# print(f"Test Balanced Accuracy: {balanced_accuracy_test*100:.2f}%")
if __name__ == "__main__":
df_train, df_val, df_test = load_dataframes()
#########################################
# Convert text into bag-of-words model
vectorizer = CountVectorizer()
#########################################
X_train = vectorizer.fit_transform(df_train["text"])
X_val = vectorizer.transform(df_val["text"])
X_test = vectorizer.transform(df_test["text"])
y_train, y_val, y_test = df_train["label"], df_val["label"], df_test["label"]
#####################################
# Model training and evaluation
#####################################
# Create a dummy classifier with the strategy to predict the most frequent class
dummy_clf = DummyClassifier(strategy="most_frequent")
dummy_clf.fit(X_train, y_train)
print("Dummy classifier:")
eval(dummy_clf, X_train, y_train, X_val, y_val, X_test, y_test)
print("\n\nLogistic regression classifier:")
model = LogisticRegression(max_iter=1000)
model.fit(X_train, y_train)
eval(model, X_train, y_train, X_val, y_val, X_test, y_test)