classifier.py

import time, random, numpy as np, argparse, sys, re, os
from types import SimpleNamespace
import csv

import torch
import torch.nn.functional as F
from torch import nn
from torch.utils.data import Dataset, DataLoader
from sklearn.metrics import classification_report, f1_score, recall_score, accuracy_score

# change it with respect to the original model
from tokenizer import BertTokenizer
from bert import BertModel
from optimizer import AdamW, SophiaG
from tqdm import tqdm

TQDM_DISABLE = False


# fix the random seed
def seed_everything(seed=11711):
    random.seed(seed)
    np.random.seed(seed)
    torch.manual_seed(seed)
    torch.cuda.manual_seed(seed)
    torch.cuda.manual_seed_all(seed)
    torch.backends.cudnn.benchmark = False
    torch.backends.cudnn.deterministic = True


class BertSentimentClassifier(torch.nn.Module):
    """
    This module performs sentiment classification using BERT embeddings on the SST dataset.

    In the SST dataset, there are 5 sentiment categories (from 0 - "negative" to 4 - "positive").
    Thus, your forward() should return one logit for each of the 5 classes.
    """

    def __init__(self, config):
        super(BertSentimentClassifier, self).__init__()
        self.num_labels = config.num_labels
        self.bert = BertModel.from_pretrained("bert-base-uncased")

        # Pretrain mode does not require updating bert paramters.
        for param in self.bert.parameters():
            if config.option == "pretrain":
                param.requires_grad = False
            elif config.option == "finetune":
                param.requires_grad = True

        ### TODO
        self.dropout = nn.Dropout(config.hidden_dropout_prob)
        self.linear_layer = nn.Linear(config.hidden_size, self.num_labels)
        # raise NotImplementedError

    def forward(self, input_ids, attention_mask):
        """Takes a batch of sentences and returns logits for sentiment classes"""
        # The final BERT contextualized embedding is the hidden state of [CLS] token (the first token).
        # HINT: you should consider what is the appropriate output to return given that
        # the training loop currently uses F.cross_entropy as the loss function.
        # Cross entropy already has a softmax therefore this should be okay
        result = self.bert(input_ids, attention_mask)
        return self.linear_layer(self.dropout(result["pooler_output"]))


class SentimentDataset(Dataset):
    def __init__(self, dataset, args):
        self.dataset = dataset
        self.p = args
        self.tokenizer = BertTokenizer.from_pretrained("bert-base-uncased")

    def __len__(self):
        return len(self.dataset)

    def __getitem__(self, idx):
        return self.dataset[idx]

    def pad_data(self, data):
        sents = [x[0] for x in data]
        labels = [x[1] for x in data]
        sent_ids = [x[2] for x in data]

        encoding = self.tokenizer(sents, return_tensors="pt", padding=True, truncation=True)
        token_ids = torch.LongTensor(encoding["input_ids"])
        attention_mask = torch.LongTensor(encoding["attention_mask"])
        labels = torch.LongTensor(labels)

        return token_ids, attention_mask, labels, sents, sent_ids

    def collate_fn(self, all_data):
        token_ids, attention_mask, labels, sents, sent_ids = self.pad_data(all_data)

        batched_data = {
            "token_ids": token_ids,
            "attention_mask": attention_mask,
            "labels": labels,
            "sents": sents,
            "sent_ids": sent_ids,
        }

        return batched_data


class SentimentTestDataset(Dataset):
    def __init__(self, dataset, args):
        self.dataset = dataset
        self.p = args
        self.tokenizer = BertTokenizer.from_pretrained("bert-base-uncased")

    def __len__(self):
        return len(self.dataset)

    def __getitem__(self, idx):
        return self.dataset[idx]

    def pad_data(self, data):
        sents = [x[0] for x in data]
        sent_ids = [x[1] for x in data]

        encoding = self.tokenizer(sents, return_tensors="pt", padding=True, truncation=True)
        token_ids = torch.LongTensor(encoding["input_ids"])
        attention_mask = torch.LongTensor(encoding["attention_mask"])

        return token_ids, attention_mask, sents, sent_ids

    def collate_fn(self, all_data):
        token_ids, attention_mask, sents, sent_ids = self.pad_data(all_data)

        batched_data = {
            "token_ids": token_ids,
            "attention_mask": attention_mask,
            "sents": sents,
            "sent_ids": sent_ids,
        }

        return batched_data


# Load the data: a list of (sentence, label)
def load_data(filename, flag="train"):
    num_labels = {}
    data = []
    if flag == "test":
        with open(filename, "r") as fp:
            for record in csv.DictReader(fp, delimiter="\t"):
                sent = record["sentence"].lower().strip()
                sent_id = record["id"].lower().strip()
                data.append((sent, sent_id))
    else:
        with open(filename, "r") as fp:
            for record in csv.DictReader(fp, delimiter="\t"):
                sent = record["sentence"].lower().strip()
                sent_id = record["id"].lower().strip()
                label = int(record["sentiment"].strip())
                if label not in num_labels:
                    num_labels[label] = len(num_labels)
                data.append((sent, label, sent_id))
        print(f"load {len(data)} data from {filename}")

    if flag == "train":
        return data, len(num_labels)
    else:
        return data


# Evaluate the model for accuracy.
def model_eval(dataloader, model, device):
    model.eval()  # switch to eval model, will turn off randomness like dropout
    y_true = []
    y_pred = []
    sents = []
    sent_ids = []
    for step, batch in enumerate(tqdm(dataloader, desc=f"eval", disable=TQDM_DISABLE)):
        b_ids, b_mask, b_labels, b_sents, b_sent_ids = (
            batch["token_ids"],
            batch["attention_mask"],
            batch["labels"],
            batch["sents"],
            batch["sent_ids"],
        )

        b_ids = b_ids.to(device)
        b_mask = b_mask.to(device)

        logits = model(b_ids, b_mask)
        logits = logits.detach().cpu().numpy()
        preds = np.argmax(logits, axis=1).flatten()

        b_labels = b_labels.flatten()
        y_true.extend(b_labels)
        y_pred.extend(preds)
        sents.extend(b_sents)
        sent_ids.extend(b_sent_ids)

    f1 = f1_score(y_true, y_pred, average="macro")
    acc = accuracy_score(y_true, y_pred)

    return acc, f1, y_pred, y_true, sents, sent_ids


def model_test_eval(dataloader, model, device):
    model.eval()  # switch to eval model, will turn off randomness like dropout
    y_pred = []
    sents = []
    sent_ids = []
    for step, batch in enumerate(tqdm(dataloader, desc=f"eval", disable=TQDM_DISABLE)):
        b_ids, b_mask, b_sents, b_sent_ids = (
            batch["token_ids"],
            batch["attention_mask"],
            batch["sents"],
            batch["sent_ids"],
        )

        b_ids = b_ids.to(device)
        b_mask = b_mask.to(device)

        logits = model(b_ids, b_mask)
        logits = logits.detach().cpu().numpy()
        preds = np.argmax(logits, axis=1).flatten()

        y_pred.extend(preds)
        sents.extend(b_sents)
        sent_ids.extend(b_sent_ids)

    return y_pred, sents, sent_ids


def save_model(model, optimizer, args, config, filepath):
    save_info = {
        "model": model.state_dict(),
        "optim": optimizer.state_dict(),
        "args": args,
        "model_config": config,
        "system_rng": random.getstate(),
        "numpy_rng": np.random.get_state(),
        "torch_rng": torch.random.get_rng_state(),
    }

    torch.save(save_info, filepath)
    print(f"save the model to {filepath}")


def train(args):
    device = torch.device("cuda") if args.use_gpu else torch.device("cpu")
    # Load data
    # Create the data and its corresponding datasets and dataloader
    train_data, num_labels = load_data(args.train, "train")
    dev_data = load_data(args.dev, "valid")

    train_dataset = SentimentDataset(train_data, args)
    dev_dataset = SentimentDataset(dev_data, args)

    train_dataloader = DataLoader(
        train_dataset, shuffle=True, batch_size=args.batch_size, collate_fn=train_dataset.collate_fn
    )
    dev_dataloader = DataLoader(
        dev_dataset, shuffle=False, batch_size=args.batch_size, collate_fn=dev_dataset.collate_fn
    )

    # Init model
    config = {
        "hidden_dropout_prob": args.hidden_dropout_prob,
        "num_labels": num_labels,
        "hidden_size": 768,
        "data_dir": ".",
        "option": args.option,
    }

    config = SimpleNamespace(**config)

    model = BertSentimentClassifier(config)
    model = model.to(device)

    lr = args.lr
    # optimizer = AdamW(model.parameters(), lr=lr)
    optimizer = SophiaG(model.parameters(), lr=lr, betas=(0.965, 0.99), rho=0.03, weight_decay=0.0)
    hess_interval = 10
    iter_num = 0

    best_dev_acc = 0

    # Run for the specified number of epochs
    for epoch in range(args.epochs):
        model.train()
        train_loss = 0
        num_batches = 0

        for batch in tqdm(train_dataloader, desc=f"train-{epoch}", disable=TQDM_DISABLE):
            b_ids, b_mask, b_labels = (batch["token_ids"], batch["attention_mask"], batch["labels"])

            b_ids = b_ids.to(device)
            b_mask = b_mask.to(device)
            b_labels = b_labels.to(device)

            logits = model(b_ids, b_mask)
            loss = F.cross_entropy(logits, b_labels.view(-1))
            loss.backward()

            # Potentially: Clip gradients using nn.utils.clip_grad_norm_(model.parameters(), 1.0)
            optimizer.step()

            optimizer.zero_grad(set_to_none=True)

            # Check if we use the Sophia Optimizer
            if (
                hasattr(optimizer, "update_hessian")
                and iter_num % hess_interval == hess_interval - 1
            ):
                # Update the Hessian EMA
                logits = model(b_ids, b_mask)
                samp_dist = torch.distributions.Categorical(logits=logits)
                y_sample = samp_dist.sample()
                loss_sampled = F.cross_entropy(logits, y_sample.view(-1))
                loss_sampled.backward()

                # Potentially: Clip gradients using nn.utils.clip_grad_norm_(model.parameters(), 1.0)
                optimizer.update_hessian(bs=args.batch_size)

                optimizer.zero_grad(set_to_none=True)

            train_loss += loss.item()
            num_batches += 1
            iter_num += 1

        train_loss = train_loss / (num_batches)

        train_acc, train_f1, *_ = model_eval(train_dataloader, model, device)
        dev_acc, dev_f1, *_ = model_eval(dev_dataloader, model, device)

        if dev_acc > best_dev_acc:
            best_dev_acc = dev_acc
            save_model(model, optimizer, args, config, args.filepath)

        print(
            f"Epoch {epoch}: train loss :: {train_loss :.3f}, train acc :: {train_acc :.3f}, dev acc :: {dev_acc :.3f}"
        )


def test(args):
    with torch.no_grad():
        device = torch.device("cuda") if args.use_gpu else torch.device("cpu")
        saved = torch.load(args.filepath)
        config = saved["model_config"]
        model = BertSentimentClassifier(config)
        model.load_state_dict(saved["model"])
        model = model.to(device)
        print(f"load model from {args.filepath}")

        dev_data = load_data(args.dev, "valid")
        dev_dataset = SentimentDataset(dev_data, args)
        dev_dataloader = DataLoader(
            dev_dataset,
            shuffle=False,
            batch_size=args.batch_size,
            collate_fn=dev_dataset.collate_fn,
        )

        test_data = load_data(args.test, "test")
        test_dataset = SentimentTestDataset(test_data, args)
        test_dataloader = DataLoader(
            test_dataset,
            shuffle=False,
            batch_size=args.batch_size,
            collate_fn=test_dataset.collate_fn,
        )

        dev_acc, dev_f1, dev_pred, dev_true, dev_sents, dev_sent_ids = model_eval(
            dev_dataloader, model, device
        )
        print("DONE DEV")
        test_pred, test_sents, test_sent_ids = model_test_eval(test_dataloader, model, device)
        print("DONE Test")
        with open(args.dev_out, "w+") as f:
            print(f"dev acc :: {dev_acc :.3f}")
            f.write(f"id \t Predicted_Sentiment \n")
            for p, s in zip(dev_sent_ids, dev_pred):
                f.write(f"{p} , {s} \n")

        with open(args.test_out, "w+") as f:
            f.write(f"id \t Predicted_Sentiment \n")
            for p, s in zip(test_sent_ids, test_pred):
                f.write(f"{p} , {s} \n")


def get_args():
    parser = argparse.ArgumentParser()
    parser.add_argument("--seed", type=int, default=11711)
    parser.add_argument("--epochs", type=int, default=10)
    parser.add_argument(
        "--option",
        type=str,
        help="pretrain: the BERT parameters are frozen; finetune: BERT parameters are updated",
        choices=("pretrain", "finetune"),
        default="pretrain",
    )
    parser.add_argument("--use_gpu", action="store_true")
    parser.add_argument("--dev_out", type=str, default="cfimdb-dev-output.txt")
    parser.add_argument("--test_out", type=str, default="cfimdb-test-output.txt")

    parser.add_argument(
        "--batch_size", help="sst: 64, cfimdb: 8 can fit a 12GB GPU", type=int, default=8
    )
    parser.add_argument("--hidden_dropout_prob", type=float, default=0.3)
    parser.add_argument(
        "--lr",
        type=float,
        help="learning rate (AdamW), default lr for 'pretrain': 1e-3, 'finetune': 1e-5",
        default=1e-5,
    )

    args = parser.parse_args()
    return args


if __name__ == "__main__":
    args = get_args()
    seed_everything(args.seed)
    # args.filepath = f'{args.option}-{args.epochs}-{args.lr}.pt'

    print("Training Sentiment Classifier on SST...")
    config = SimpleNamespace(
        filepath="sst-classifier.pt",
        lr=args.lr,
        use_gpu=args.use_gpu,
        epochs=args.epochs,
        batch_size=args.batch_size,
        hidden_dropout_prob=args.hidden_dropout_prob,
        train="data/ids-sst-train.csv",
        dev="data/ids-sst-dev.csv",
        test="data/ids-sst-test-student.csv",
        option=args.option,
        dev_out="predictions/" + args.option + "-sst-dev-out.csv",
        test_out="predictions/" + args.option + "-sst-test-out.csv",
    )

    train(config)

    print("Evaluating on SST...")
    test(config)