bert_classification.py

from pytorch_pretrained_bert.tokenization import BertTokenizer, WordpieceTokenizer
from pytorch_pretrained_bert.modeling import BertForPreTraining,BertPreTrainedModel, BertModel, BertConfig, BertForMaskedLM, BertForSequenceClassification
from pathlib import Path
import torch
from torch import nn
from torch.nn import CrossEntropyLoss
import re
from torch import Tensor
import torch.nn.functional as F
#from fastai.text import Tokenizer, Vocab
import pandas as pd
import collections
import os
import pdb
from tqdm import tqdm, trange
import sys
import random
import numpy as np
import csv
from sklearn.model_selection import train_test_split
module_path = os.path.abspath(os.path.join('..'))
if module_path not in sys.path:
    sys.path.append(module_path)
from sklearn.metrics import roc_curve, auc
from sklearn.preprocessing import LabelBinarizer, label_binarize
import argparse
from torch.utils.data import TensorDataset, DataLoader, RandomSampler, SequentialSampler
from torch.utils.data.distributed import DistributedSampler
from pytorch_pretrained_bert.optimization import BertAdam
from tqdm.auto import tqdm
import logging

parser = argparse.ArgumentParser(description='BERT Fine-Training')
parser.add_argument(
    '--fine_tune', '-ft', action='store_true', help='Fine-Tune on dataset')
parser.add_argument(
    '--resume', '-r', action='store_true', help='resume from checkpoint')
parser.add_argument(
    '--eval', '-e', action='store_true', help='Run eval on checkpoint')
parser.add_argument(
    '--predict', '-p', action='store_true', help='Run predictions on checkpoint')
arg = parser.parse_args()

if not os.path.exists('Data'):
    os.makedirs('Data')
if not os.path.exists('Data/output'):
    os.makedirs('Data/output')

#Read dataset
df3 = pd.read_csv('Data/cleaned.csv')

#Splitting data into train, test and val
X=df3.sample(frac=0.5,random_state=200)
test=df3.drop(X.index)
train=X.sample(frac=0.6,random_state=200)
val=X.drop(train.index)

print("Train Shape", train.shape)
print("Val Shape", val.shape)
print("Test Shape", test.shape)
train.to_csv('Data/train.csv',encoding='utf-8', index=False)
val.to_csv('Data/val.csv',encoding='utf-8', index=False)
test.to_csv('Data/test.csv',encoding='utf-8', index=False)

logging.basicConfig(format='%(asctime)s - %(levelname)s - %(name)s -   %(message)s',
                    datefmt='%m/%d/%Y %H:%M:%S',
                    level=logging.INFO)
logger = logging.getLogger(__name__)

DATA_PATH=Path('Data/')
DATA_PATH.mkdir(exist_ok=True)

CLAS_DATA_PATH=DATA_PATH/'output'
CLAS_DATA_PATH.mkdir(exist_ok=True)

model_state_dict = None
#Set this according to your dataset
input_col = 2 # 0 based index column input to the model
output_col = 1 # 0 based index column label to the model

BERT_PRETRAINED_PATH = Path('uncased_L-12_H-768_A-12')

"""## Model Parameters"""

args = {
    "train_size": -1,
    "val_size": -1,
    "full_data_dir": DATA_PATH,
    "data_dir": DATA_PATH,
    "task_name": "news_cat_label",
    "no_cuda": False,
    "bert_model": "bert-base-uncased",
    "output_dir": CLAS_DATA_PATH,
    "max_seq_length": 50,
    "do_train": True,
    "do_eval": True,
    "do_lower_case": True,
    "train_batch_size": 32,
    "eval_batch_size": 8,
    "learning_rate": 3e-5,
    "num_train_epochs": 4.0,
    "warmup_proportion": 0.1,
    "no_cuda": False,
    "local_rank": -1,
    "seed": 42,
    "gradient_accumulation_steps": 1,
    "optimize_on_cpu": False,
    "fp16": False,
    "loss_scale": 128
}
output_model_file = os.path.join(args['output_dir'], "ckpt.t7")
"""###  Model Class"""

class BertForSequenceClassification(BertPreTrainedModel):
    """BERT model for classification.
    This module is composed of the BERT model with a linear layer on top of
    the pooled output.
    Params:
        `config`: a BertConfig class instance with the configuration to build a new model.
        `num_labels`: the number of classes for the classifier. Default = 2.
    Inputs:
        `input_ids`: a torch.LongTensor of shape [batch_size, sequence_length]
            with the word token indices in the vocabulary(see the tokens preprocessing logic in the scripts
            `extract_features.py`, `run_classifier.py` and `run_squad.py`)
        `token_type_ids`: an optional torch.LongTensor of shape [batch_size, sequence_length] with the token
            types indices selected in [0, 1]. Type 0 corresponds to a `sentence A` and type 1 corresponds to
            a `sentence B` token (see BERT paper for more details).
        `attention_mask`: an optional torch.LongTensor of shape [batch_size, sequence_length] with indices
            selected in [0, 1]. It's a mask to be used if the input sequence length is smaller than the max
            input sequence length in the current batch. It's the mask that we typically use for attention when
            a batch has varying length sentences.
        `labels`: labels for the classification output: torch.LongTensor of shape [batch_size]
            with indices selected in [0, ..., num_labels].
    Outputs:
        if `labels` is not `None`:
            Outputs the CrossEntropy classification loss of the output with the labels.
        if `labels` is `None`:
            Outputs the classification logits of shape [batch_size, num_labels].
    Example usage:
    ```python
    # Already been converted into WordPiece token ids
    input_ids = torch.LongTensor([[31, 51, 99], [15, 5, 0]])
    input_mask = torch.LongTensor([[1, 1, 1], [1, 1, 0]])
    token_type_ids = torch.LongTensor([[0, 0, 1], [0, 1, 0]])
    config = BertConfig(vocab_size_or_config_json_file=32000, hidden_size=768,
        num_hidden_layers=12, num_attention_heads=12, intermediate_size=3072)
    num_labels = 2
    model = BertForSequenceClassification(config, num_labels)
    logits = model(input_ids, token_type_ids, input_mask)
    ```
    """
    def __init__(self, config, num_labels):
        super(BertForSequenceClassification, self).__init__(config)
        self.num_labels = num_labels
        self.bert = BertModel(config)
        self.dropout = nn.Dropout(config.hidden_dropout_prob)
        self.classifier = nn.Linear(config.hidden_size, num_labels)
        self.apply(self.init_bert_weights)

    def forward(self, input_ids, token_type_ids=None, attention_mask=None, labels=None):
        _, pooled_output = self.bert(input_ids, token_type_ids, attention_mask, output_all_encoded_layers=False)
        pooled_output = self.dropout(pooled_output)
        logits = self.classifier(pooled_output)

        if labels is not None:
            loss_fct = CrossEntropyLoss()
            loss = loss_fct(logits.view(-1, self.num_labels), labels.view(-1))
            return loss
        else:
            return logits
        
    def freeze_bert_encoder(self):
        for param in self.bert.parameters():
            print(param)
            param.requires_grad = False
    
    def unfreeze_bert_encoder(self):
        for param in self.bert.parameters():
            param.requires_grad = True

"""## Data representation class"""

class InputExample(object):
    """A single training/test example for simple sequence classification."""

    def __init__(self, guid, text_a, text_b=None, labels=None):
        """Constructs a InputExample.

        Args:
            guid: Unique id for the example.
            text_a: string. The untokenized text of the first sequence. For single
            sequence tasks, only this sequence must be specified.
            text_b: (Optional) string. The untokenized text of the second sequence.
            Only must be specified for sequence pair tasks.
            labels: (Optional) [string]. The label of the example. This should be
            specified for train and dev examples, but not for test examples.
        """
        self.guid = guid
        self.text_a = text_a
        self.text_b = text_b
        self.labels = labels


class InputFeatures(object):
    """A single set of features of data."""

    def __init__(self, input_ids, input_mask, segment_ids, label_ids):
        self.input_ids = input_ids
        self.input_mask = input_mask
        self.segment_ids = segment_ids
        self.label_ids = label_ids

class DataProcessor(object):
    """Base class for data converters for sequence classification data sets."""

    def get_train_examples(self, data_dir):
        """Gets a collection of `InputExample`s for the train set."""
        raise NotImplementedError()

    def get_dev_examples(self, data_dir):
        """Gets a collection of `InputExample`s for the dev set."""
        raise NotImplementedError()
    
    def get_test_examples(self, data_dir, data_file_name, size=-1):
        """Gets a collection of `InputExample`s for the dev set."""
        raise NotImplementedError() 

    def get_labels(self):
        """Gets the list of labels for this data set."""
        raise NotImplementedError()

class LabelTextProcessor(DataProcessor):
    
    def __init__(self, data_dir):
        self.data_dir = data_dir
        self.labels = None
    
    
    def get_train_examples(self, data_dir, size=-1):
        filename = 'train.csv'
        logger.info("LOOKING AT {}".format(os.path.join(data_dir, filename)))
        if size == -1:
            data_df = pd.read_csv(os.path.join(data_dir, filename),engine=None)
            return self._create_examples(data_df, "train")
        else:
            data_df = pd.read_csv(os.path.join(data_dir, filename))
            return self._create_examples(data_df.sample(size), "train")
        
    def get_dev_examples(self, data_dir, size=-1):
        """See base class."""
        filename = 'val.csv'
        if size == -1:
            data_df = pd.read_csv(os.path.join(data_dir, filename))
            return self._create_examples(data_df, "dev")
        else:
            data_df = pd.read_csv(os.path.join(data_dir, filename))
            return self._create_examples(data_df.sample(size), "dev")
    
    def get_test_examples(self, data_dir, data_file_name, size=-1):
        data_df = pd.read_csv(os.path.join(data_dir, data_file_name))
        if size == -1:
            return self._create_examples(data_df, "test")
        else:
            return self._create_examples(data_df.sample(size), "test")

    def get_labels(self):
        """See base class."""
        return ['ARTS', 'ARTS & CULTURE', 'BLACK VOICES', 'BUSINESS', 'COLLEGE', 'COMEDY', 'CRIME', 'CULTURE & ARTS', 'DIVORCE', 'EDUCATION', 'ENTERTAINMENT', 'ENVIRONMENT', 'FIFTY', 'FOOD & DRINK', 'GOOD NEWS', 'GREEN', 'HEALTHY LIVING', 'HOME & LIVING', 'IMPACT', 'LATINO VOICES', 'MEDIA', 'MONEY', 'PARENTING', 'PARENTS', 'POLITICS', 'QUEER VOICES', 'RELIGION', 'SCIENCE', 'SPORTS', 'STYLE', 'STYLE & BEAUTY', 'TASTE', 'TECH', 'TRAVEL', 'WEDDINGS', 'WEIRD NEWS', 'WELLNESS', 'WOMEN', 'WORLD NEWS', 'WORLDPOST']
        #return ["0", "1"]

    def _create_examples(self, df, set_type, labels_available=True):
        """Creates examples for the training and dev sets."""
        examples = []
        for (i, row) in enumerate(df.values):
            guid = "%s-%s" % (set_type, i)
            text_a = row[input_col]
            if labels_available:
                labels = row[output_col]
                #print('hiiiii',labels)
            else:
                labels = []
                print("No Label Found")
            examples.append(
                InputExample(guid=guid, text_a=text_a, labels=labels))
        return examples

def convert_examples_to_features(examples, label_list, max_seq_length, tokenizer):
    """Loads a data file into a list of `InputBatch`s."""

    label_map = {label : i for i, label in enumerate(label_list)}
    
    features = []
    for (ex_index, example) in enumerate(examples):
        tokens_a = tokenizer.tokenize(example.text_a)

        tokens_b = None
        if example.text_b:
            tokens_b = tokenizer.tokenize(example.text_b)
            # Modifies `tokens_a` and `tokens_b` in place so that the total
            # length is less than the specified length.
            # Account for [CLS], [SEP], [SEP] with "- 3"
            _truncate_seq_pair(tokens_a, tokens_b, max_seq_length - 3)
        else:
            # Account for [CLS] and [SEP] with "- 2"
            if len(tokens_a) > max_seq_length - 2:
                tokens_a = tokens_a[:(max_seq_length - 2)]

        # The convention in BERT is:
        # (a) For sequence pairs:
        #  tokens:   [CLS] is this jack ##son ##ville ? [SEP] no it is not . [SEP]
        #  type_ids: 0   0  0    0    0     0       0 0    1  1  1  1   1 1
        # (b) For single sequences:
        #  tokens:   [CLS] the dog is hairy . [SEP]
        #  type_ids: 0   0   0   0  0     0 0
        #
        # Where "type_ids" are used to indicate whether this is the first
        # sequence or the second sequence. The embedding vectors for `type=0` and
        # `type=1` were learned during pre-training and are added to the wordpiece
        # embedding vector (and position vector). This is not *strictly* necessary
        # since the [SEP] token unambigiously separates the sequences, but it makes
        # it easier for the model to learn the concept of sequences.
        #
        # For classification tasks, the first vector (corresponding to [CLS]) is
        # used as as the "sentence vector". Note that this only makes sense because
        # the entire model is fine-tuned.
        tokens = ["[CLS]"] + tokens_a + ["[SEP]"]
        segment_ids = [0] * len(tokens)

        if tokens_b:
            tokens += tokens_b + ["[SEP]"]
            segment_ids += [1] * (len(tokens_b) + 1)

        input_ids = tokenizer.convert_tokens_to_ids(tokens)

        # The mask has 1 for real tokens and 0 for padding tokens. Only real
        # tokens are attended to.
        input_mask = [1] * len(input_ids)

        # Zero-pad up to the sequence length.
        padding = [0] * (max_seq_length - len(input_ids))
        input_ids += padding
        input_mask += padding
        segment_ids += padding

        assert len(input_ids) == max_seq_length
        assert len(input_mask) == max_seq_length
        assert len(segment_ids) == max_seq_length

        labels_ids = label_map[example.labels]
        if ex_index < 0:
            logger.info("*** Example ***")
            logger.info("guid: %s" % (example.guid))
            logger.info("tokens: %s" % " ".join(
                    [str(x) for x in tokens]))
            logger.info("input_ids: %s" % " ".join([str(x) for x in input_ids]))
            logger.info("input_mask: %s" % " ".join([str(x) for x in input_mask]))
            logger.info(
                    "segment_ids: %s" % " ".join([str(x) for x in segment_ids]))
            logger.info("label: %s (id = %s)" % (example.labels, labels_ids))

        features.append(
                InputFeatures(input_ids=input_ids,
                              input_mask=input_mask,
                              segment_ids=segment_ids,
                              label_ids=labels_ids))
    return features

def _truncate_seq_pair(tokens_a, tokens_b, max_length):
    """Truncates a sequence pair in place to the maximum length."""

    # This is a simple heuristic which will always truncate the longer sequence
    # one token at a time. This makes more sense than truncating an equal percent
    # of tokens from each, since if one sequence is very short then each token
    # that's truncated likely contains more information than a longer sequence.
    while True:
        total_length = len(tokens_a) + len(tokens_b)
        if total_length <= max_length:
            break
        if len(tokens_a) > len(tokens_b):
            tokens_a.pop()
        else:
            tokens_b.pop()

"""## Metric functions"""

def accuracy(out, labels):
    outputs = np.argmax(out, axis=1)
    return np.sum(outputs == labels)

def accuracy_thresh(y_pred:Tensor, y_true:Tensor, thresh:float=0.5, sigmoid:bool=True):
    "Compute accuracy when `y_pred` and `y_true` are the same size."
    if sigmoid: y_pred = y_pred.sigmoid()
#     return ((y_pred>thresh)==y_true.byte()).float().mean().item()
    return np.mean(((y_pred>thresh)==y_true.byte()).float().cpu().numpy(), axis=1).sum()


def fbeta(y_pred:Tensor, y_true:Tensor, thresh:float=0.2, beta:float=2, eps:float=1e-9, sigmoid:bool=True):
    "Computes the f_beta between `preds` and `targets`"
    beta2 = beta ** 2
    if sigmoid: y_pred = y_pred.sigmoid()
    y_pred = (y_pred>thresh).float()
    y_true = y_true.float()
    TP = (y_pred*y_true).sum(dim=1)
    prec = TP/(y_pred.sum(dim=1)+eps)
    rec = TP/(y_true.sum(dim=1)+eps)
    res = (prec*rec)/(prec*beta2+rec+eps)*(1+beta2)
    return res.mean().item()

"""## Training warmup"""

def warmup_linear(x, warmup=0.002):
    if x < warmup:
        return x/warmup
    return 1.0 - x

processors = {
    "news_cat_label": LabelTextProcessor
}

# Setup GPU parameters

if args["local_rank"] == -1 or args["no_cuda"]:
    device = torch.device("cuda" if torch.cuda.is_available() and not args["no_cuda"] else "cpu")
    n_gpu = torch.cuda.device_count()
#     n_gpu = 1
else:
    torch.cuda.set_device(args['local_rank'])
    device = torch.device("cuda", args['local_rank'])
    n_gpu = 1
    # Initializes the distributed backend which will take care of sychronizing nodes/GPUs
    torch.distributed.init_process_group(backend='nccl')
logger.info("device: {} n_gpu: {}, distributed training: {}, 16-bits training: {}".format(
        device, n_gpu, bool(args['local_rank'] != -1), args['fp16']))

args['train_batch_size'] = int(args['train_batch_size'] / args['gradient_accumulation_steps'])

random.seed(args['seed'])
np.random.seed(args['seed'])
torch.manual_seed(args['seed'])
if n_gpu > 0:
    torch.cuda.manual_seed_all(args['seed'])

task_name = args['task_name'].lower()

if task_name not in processors:
    raise ValueError("Task not found: %s" % (task_name))

processor = processors[task_name](args['data_dir'])
label_list = processor.get_labels()
num_labels = len(label_list)

tokenizer = BertTokenizer.from_pretrained('bert-base-uncased', do_lower_case=args['do_lower_case'])



train_examples = None
num_train_steps = None
if args['do_train']:
    train_examples = processor.get_train_examples(args['full_data_dir'], size=args['train_size'])
    num_train_steps = int(
        len(train_examples) / args['train_batch_size'] / args['gradient_accumulation_steps'] * args['num_train_epochs'])

"""## Prepare model"""

def get_model():
    if model_state_dict:
        model = BertForSequenceClassification.from_pretrained(args['bert_model'], num_labels = num_labels, state_dict=model_state_dict)
    else:
        model = BertForSequenceClassification.from_pretrained(args['bert_model'], num_labels = num_labels)
    return model

model = get_model()
model.to(device)

if args['local_rank'] != -1:
    try:
        from apex.parallel import DistributedDataParallel as DDP
    except ImportError:
        raise ImportError("Please install apex from https://www.github.com/nvidia/apex to use distributed and fp16 training.")

    model = DDP(model)
elif n_gpu > 1:
    model = torch.nn.DataParallel(model)

from torch.optim.lr_scheduler import _LRScheduler, Optimizer

class CyclicLR(object):
    """Sets the learning rate of each parameter group according to
    cyclical learning rate policy (CLR). The policy cycles the learning
    rate between two boundaries with a constant frequency, as detailed in
    the paper `Cyclical Learning Rates for Training Neural Networks`_.
    The distance between the two boundaries can be scaled on a per-iteration
    or per-cycle basis.
    Cyclical learning rate policy changes the learning rate after every batch.
    `batch_step` should be called after a batch has been used for training.
    To resume training, save `last_batch_iteration` and use it to instantiate `CycleLR`.
    This class has three built-in policies, as put forth in the paper:
    "triangular":
        A basic triangular cycle w/ no amplitude scaling.
    "triangular2":
        A basic triangular cycle that scales initial amplitude by half each cycle.
    "exp_range":
        A cycle that scales initial amplitude by gamma**(cycle iterations) at each
        cycle iteration.
    This implementation was adapted from the github repo: `bckenstler/CLR`_
    Args:
        optimizer (Optimizer): Wrapped optimizer.
        base_lr (float or list): Initial learning rate which is the
            lower boundary in the cycle for eachparam groups.
            Default: 0.001
        max_lr (float or list): Upper boundaries in the cycle for
            each parameter group. Functionally,
            it defines the cycle amplitude (max_lr - base_lr).
            The lr at any cycle is the sum of base_lr
            and some scaling of the amplitude; therefore
            max_lr may not actually be reached depending on
            scaling function. Default: 0.006
        step_size (int): Number of training iterations per
            half cycle. Authors suggest setting step_size
            2-8 x training iterations in epoch. Default: 2000
        mode (str): One of {triangular, triangular2, exp_range}.
            Values correspond to policies detailed above.
            If scale_fn is not None, this argument is ignored.
            Default: 'triangular'
        gamma (float): Constant in 'exp_range' scaling function:
            gamma**(cycle iterations)
            Default: 1.0
        scale_fn (function): Custom scaling policy defined by a single
            argument lambda function, where
            0 <= scale_fn(x) <= 1 for all x >= 0.
            mode paramater is ignored
            Default: None
        scale_mode (str): {'cycle', 'iterations'}.
            Defines whether scale_fn is evaluated on
            cycle number or cycle iterations (training
            iterations since start of cycle).
            Default: 'cycle'
        last_batch_iteration (int): The index of the last batch. Default: -1
    Example:
        >>> optimizer = torch.optim.SGD(model.parameters(), lr=0.1, momentum=0.9)
        >>> scheduler = torch.optim.CyclicLR(optimizer)
        >>> data_loader = torch.utils.data.DataLoader(...)
        >>> for epoch in range(10):
        >>>     for batch in data_loader:
        >>>         scheduler.batch_step()
        >>>         train_batch(...)
    .. _Cyclical Learning Rates for Training Neural Networks: https://arxiv.org/abs/1506.01186
    .. _bckenstler/CLR: https://github.com/bckenstler/CLR
    """

    def __init__(self, optimizer, base_lr=1e-3, max_lr=6e-3,
                 step_size=2000, mode='triangular', gamma=1.,
                 scale_fn=None, scale_mode='cycle', last_batch_iteration=-1):

        self.optimizer = optimizer

        if isinstance(base_lr, list) or isinstance(base_lr, tuple):
            if len(base_lr) != len(optimizer.param_groups):
                raise ValueError("expected {} base_lr, got {}".format(
                    len(optimizer.param_groups), len(base_lr)))
            self.base_lrs = list(base_lr)
        else:
            self.base_lrs = [base_lr] * len(optimizer.param_groups)

        if isinstance(max_lr, list) or isinstance(max_lr, tuple):
            if len(max_lr) != len(optimizer.param_groups):
                raise ValueError("expected {} max_lr, got {}".format(
                    len(optimizer.param_groups), len(max_lr)))
            self.max_lrs = list(max_lr)
        else:
            self.max_lrs = [max_lr] * len(optimizer.param_groups)

        self.step_size = step_size

        if mode not in ['triangular', 'triangular2', 'exp_range'] \
                and scale_fn is None:
            raise ValueError('mode is invalid and scale_fn is None')

        self.mode = mode
        self.gamma = gamma

        if scale_fn is None:
            if self.mode == 'triangular':
                self.scale_fn = self._triangular_scale_fn
                self.scale_mode = 'cycle'
            elif self.mode == 'triangular2':
                self.scale_fn = self._triangular2_scale_fn
                self.scale_mode = 'cycle'
            elif self.mode == 'exp_range':
                self.scale_fn = self._exp_range_scale_fn
                self.scale_mode = 'iterations'
        else:
            self.scale_fn = scale_fn
            self.scale_mode = scale_mode

        self.batch_step(last_batch_iteration + 1)
        self.last_batch_iteration = last_batch_iteration

    def batch_step(self, batch_iteration=None):
        if batch_iteration is None:
            batch_iteration = self.last_batch_iteration + 1
        self.last_batch_iteration = batch_iteration
        for param_group, lr in zip(self.optimizer.param_groups, self.get_lr()):
            param_group['lr'] = lr

    def _triangular_scale_fn(self, x):
        return 1.

    def _triangular2_scale_fn(self, x):
        return 1 / (2. ** (x - 1))

    def _exp_range_scale_fn(self, x):
        return self.gamma**(x)

    def get_lr(self):
        step_size = float(self.step_size)
        cycle = np.floor(1 + self.last_batch_iteration / (2 * step_size))
        x = np.abs(self.last_batch_iteration / step_size - 2 * cycle + 1)

        lrs = []
        param_lrs = zip(self.optimizer.param_groups, self.base_lrs, self.max_lrs)
        for param_group, base_lr, max_lr in param_lrs:
            base_height = (max_lr - base_lr) * np.maximum(0, (1 - x))
            if self.scale_mode == 'cycle':
                lr = base_lr + base_height * self.scale_fn(cycle)
            else:
                lr = base_lr + base_height * self.scale_fn(self.last_batch_iteration)
            lrs.append(lr)
        return lrs


"""## Prepare optimizer"""
param_optimizer = list(model.named_parameters())
no_decay = ['bias', 'LayerNorm.bias', 'LayerNorm.weight']
optimizer_grouped_parameters = [
    {'params': [p for n, p in param_optimizer if not any(nd in n for nd in no_decay)], 'weight_decay': 0.01},
    {'params': [p for n, p in param_optimizer if any(nd in n for nd in no_decay)], 'weight_decay': 0.0}
    ]
t_total = num_train_steps
if args['local_rank'] != -1:
    t_total = t_total // torch.distributed.get_world_size()
if args['fp16']:
    try:
        from apex.optimizers import FP16_Optimizer
        from apex.optimizers import FusedAdam
    except ImportError:
        raise ImportError("Please install apex from https://www.github.com/nvidia/apex to use distributed and fp16 training.")

    optimizer = FusedAdam(optimizer_grouped_parameters,
                          lr=args['learning_rate'],
                          bias_correction=False,
                          max_grad_norm=1.0)
    if args['loss_scale'] == 0:
        optimizer = FP16_Optimizer(optimizer, dynamic_loss_scale=True)
    else:
        optimizer = FP16_Optimizer(optimizer, static_loss_scale=args['loss_scale'])

else:
    optimizer = BertAdam(optimizer_grouped_parameters,
                         lr=args['learning_rate'],
                         warmup=args['warmup_proportion'],
                         t_total=t_total)

scheduler = CyclicLR(optimizer, base_lr=2e-5, max_lr=5e-5, step_size=2500, last_batch_iteration=0)

"""## Multi-Class ROC"""

def multiclass_roc_auc_score(y_test, y_pred, average="macro"):
    
    lb = LabelBinarizer()
    lb.fit(y_test)
    y_test = lb.transform(y_test)
    y_pred = lb.transform(y_pred)
    
    return roc_auc_score(y_test, y_pred, average=average)

"""## **EVAL Function**"""

eval_examples = processor.get_dev_examples(args['data_dir'], size=args['val_size'])
def eval():
    args['output_dir'].mkdir(exist_ok=True)

    
    eval_features = convert_examples_to_features(
        eval_examples, label_list, args['max_seq_length'], tokenizer)
    logger.info("***** Running evaluation *****")
    logger.info("  Num examples = %d", len(eval_examples))
    logger.info("  Batch size = %d", args['eval_batch_size'])
    all_input_ids = torch.tensor([f.input_ids for f in eval_features], dtype=torch.long)
    all_input_mask = torch.tensor([f.input_mask for f in eval_features], dtype=torch.long)
    all_segment_ids = torch.tensor([f.segment_ids for f in eval_features], dtype=torch.long)
    all_label_ids = torch.tensor([f.label_ids for f in eval_features], dtype=torch.long)
    eval_data = TensorDataset(all_input_ids, all_input_mask, all_segment_ids, all_label_ids)
    # Run prediction for full data
    eval_sampler = SequentialSampler(eval_data)
    eval_dataloader = DataLoader(eval_data, sampler=eval_sampler, batch_size=args['eval_batch_size'])
    
    all_logits = None
    all_labels = None
    
    model.eval()
    eval_loss, eval_accuracy = 0, 0
    nb_eval_steps, nb_eval_examples = 0, 0
    for input_ids, input_mask, segment_ids, label_ids in eval_dataloader:
        input_ids = input_ids.to(device)
        input_mask = input_mask.to(device)
        segment_ids = segment_ids.to(device)
        label_ids = label_ids.to(device)

        with torch.no_grad():
            tmp_eval_loss = model(input_ids, segment_ids, input_mask, label_ids)
            logits = model(input_ids, segment_ids, input_mask)
            
        logit = logits
        a_label = label_ids
        logits = logits.detach().cpu().numpy()
        label_ids = label_ids.to('cpu').numpy()
        tmp_eval_accuracy = accuracy(logits, label_ids)
        
        if all_logits is None:
            all_logits = logit.detach().cpu().numpy()
        else:
            all_logits = np.concatenate((all_logits, logit.detach().cpu().numpy()), axis=0)
            
        if all_labels is None:
            all_labels = a_label.detach().cpu().numpy()
        else:    
            all_labels = np.concatenate((all_labels, a_label.detach().cpu().numpy()), axis=0)
            
        eval_loss += tmp_eval_loss.mean().item()
        eval_accuracy += tmp_eval_accuracy

        nb_eval_examples += input_ids.size(0)
        nb_eval_steps += 1

    eval_loss = eval_loss / nb_eval_steps
    eval_accuracy = eval_accuracy / nb_eval_examples
    
    # ROC-AUC calcualation
    # Compute ROC curve and ROC area for each class
    fpr = dict()
    tpr = dict()
    roc_auc = dict()
    all_labels = label_binarize(all_labels, classes=np.arange(num_labels))
    for i in range(num_labels):
        fpr[i], tpr[i], _ = roc_curve(all_labels[:, i], all_logits[:, i])
        roc_auc[i] = auc(fpr[i], tpr[i])
    
    # Compute micro-average ROC curve and ROC area
    fpr["micro"], tpr["micro"], _ = roc_curve(all_labels.ravel(), all_logits.ravel())
    roc_auc["micro"] = auc(fpr["micro"], tpr["micro"])
    
    loss = tr_loss/nb_tr_steps if tr_loss else None
    result = {'eval_loss': eval_loss,
              'eval_accuracy': eval_accuracy,
              'global_step': global_step,
              'loss': loss,
              'roc_auc': roc_auc
             }

    output_eval_file = os.path.join(args['output_dir'], "eval_results.txt")
    with open(output_eval_file, "w") as writer:
        logger.info("***** Eval results *****")
        for key in sorted(result.keys()):
            logger.info("  %s = %s", key, str(result[key]))
            writer.write("%s = %s\n" % (key, str(result[key])))


"""### Load training data"""
train_features = convert_examples_to_features(
train_examples, label_list, args['max_seq_length'], tokenizer)

logger.info("***** Running training *****")
logger.info("  Num examples = %d", len(train_examples))
logger.info("  Batch size = %d", args['train_batch_size'])
logger.info("  Num steps = %d", num_train_steps)
all_input_ids = torch.tensor([f.input_ids for f in train_features], dtype=torch.long)
all_input_mask = torch.tensor([f.input_mask for f in train_features], dtype=torch.long)
all_segment_ids = torch.tensor([f.segment_ids for f in train_features], dtype=torch.long)
all_label_ids = torch.tensor([f.label_ids for f in train_features], dtype=torch.long)
train_data = TensorDataset(all_input_ids, all_input_mask, all_segment_ids, all_label_ids)
if args['local_rank'] == -1:
    train_sampler = RandomSampler(train_data)
else:
    train_sampler = DistributedSampler(train_data)
train_dataloader = DataLoader(train_data, sampler=train_sampler, batch_size=args['train_batch_size'])


"""### Train Model"""

tr_loss = 0
nb_tr_steps = 0
global_step = 0
    
def fit(num_epocs=args['num_train_epochs']):
    global_step = 0
    
    if arg.resume:
        print('==> Resuming from checkpoint..')
        checkpoint = torch.load(output_model_file)
        model.load_state_dict(checkpoint['state_dict'])
        optimizer.load_state_dict(checkpoint['optimizer'])
   
    model.train()
    
    for i_ in trange(int(num_epocs), desc="Epoch"):
        # Load a trained model that you have fine-tuned
        tr_loss = 0
        nb_tr_examples, nb_tr_steps = 0, 0
        for step, batch in enumerate(tqdm(train_dataloader, desc="Iteration")):
            
            batch = tuple(t.to(device) for t in batch)
            input_ids, input_mask, segment_ids, label_ids = batch
            loss = model(input_ids, segment_ids, input_mask, label_ids)
            if n_gpu > 1:
                loss = loss.mean() # mean() to average on multi-gpu.
            if args['gradient_accumulation_steps'] > 1:
                loss = loss / args['gradient_accumulation_steps']

            if args['fp16']:
                optimizer.backward(loss)
            else:
                loss.backward()

            tr_loss += loss.item()
            nb_tr_examples += input_ids.size(0)
            nb_tr_steps += 1
            if (step + 1) % args['gradient_accumulation_steps'] == 0:
                #scheduler.batch_step()
                # modify learning rate with special warm up BERT uses
                lr_this_step = args['learning_rate'] * warmup_linear(global_step/t_total, args['warmup_proportion'])
                for param_group in optimizer.param_groups:
                    param_group['lr'] = lr_this_step
                optimizer.step()
                optimizer.zero_grad()
                global_step += 1
      
        logger.info('Loss after epoc {}'.format(tr_loss / nb_tr_steps))
        logger.info('Eval after epoc {}'.format(i_+1))
        
        result = eval()
        # Save a trained model
        save_checkpoint = {
          'epoch': i_ + 1,
          'max_length': args['max_seq_length'],
          'state_dict': model.state_dict(),
          'optimizer' : optimizer.state_dict(),
        }
        torch.save(save_checkpoint, output_model_file)

# Freeze BERT layers for 1 epoch
# model.freeze_bert_encoder()
# model.unfreeze_bert_encoder()


"""### Model Evaluation"""

# Load a trained model that you have fine-tuned
# model_state_dict = torch.load(output_model_file)
# model = BertForSequenceClassification.from_pretrained(args['bert_model'], num_labels = num_labels, state_dict=model_state_dict)
# model.to(device)
# eval()

def predict(model, path, test_filename='test1.csv'):
    predict_processor = LabelTextProcessor(path)
    test_examples = predict_processor.get_test_examples(path, test_filename, size=-1)
    
    # Hold input data for returning it 
    input_data = [{ 'id': input_example.guid, 'comment_text': input_example.text_a } for input_example in test_examples]
    pred_file = os.path.join(args['data_dir'], test_filename)
    df = pd.read_csv(pred_file)
    test_features = convert_examples_to_features(
        test_examples, label_list, args['max_seq_length'], tokenizer)
    
    logger.info("***** Running pathrediction *****")
    logger.info("  Num examples = %d", len(test_examples))
    logger.info("  Batch size = %d", args['eval_batch_size'])
    
    all_input_ids = torch.tensor([f.input_ids for f in test_features], dtype=torch.long)
    all_input_mask = torch.tensor([f.input_mask for f in test_features], dtype=torch.long)
    all_segment_ids = torch.tensor([f.segment_ids for f in test_features], dtype=torch.long)

    test_data = TensorDataset(all_input_ids, all_input_mask, all_segment_ids)
    
    # Run prediction for full data
    test_sampler = SequentialSampler(test_data)
    test_dataloader = DataLoader(test_data, sampler=test_sampler, batch_size=args['eval_batch_size'])
    
    all_outputs = None
    
    model.eval()
    eval_loss, eval_accuracy = 0, 0
    nb_eval_steps, nb_eval_examples = 0, 0
    for step, batch in enumerate(tqdm(test_dataloader, desc="Prediction Iteration")):
        input_ids, input_mask, segment_ids = batch
        input_ids = input_ids.to(device)
        input_mask = input_mask.to(device)
        segment_ids = segment_ids.to(device)

        with torch.no_grad():
            logits = model(input_ids, segment_ids, input_mask)
            logits = F.softmax(logits, -1)
            outputs = np.argmax(logits.detach().cpu().numpy(), axis=1)
            print(outputs)

        if all_outputs is None:
            all_outputs =  outputs
        else:
            all_outputs = np.concatenate((all_outputs, outputs), axis=0)
            
        nb_eval_examples += input_ids.size(0)
        nb_eval_steps += 1

    df["Predictions"] = all_outputs
    return df

def main():
    
    if arg.fine_tune:
        fit()

    if arg.eval:
        checkpoint = torch.load(output_model_file)
        model.load_state_dict(checkpoint['state_dict'])
        eval()

    if arg.predict:
        checkpoint = torch.load(output_model_file)
        model.load_state_dict(checkpoint['state_dict'])
        result = predict(model, DATA_PATH)
        result.to_csv(DATA_PATH/'results.csv', index=None)


if __name__ == '__main__':
    main()