clipGPT.py

from transformers import AutoTokenizer, AutoModel
import clip
import skimage.io as io
import PIL.Image

import torch
import torch.nn as nn
from torch.utils.data import Dataset, DataLoader
from torch.nn import functional as F

import pandas as pd
import numpy as np
import time
import json
import nltk
nltk.download('punkt')


class ClipGPT2Model(nn.Module):
    def __init__(self, img_feature_length, img_feature_size = 512):
        super(ClipGPT2Model, self).__init__()
        torch.cuda.empty_cache()
        gc.collect()
        self.img_feature_length = img_feature_length

        self.gpt = GPT2LMHeadModel.from_pretrained('gpt2')
        self.gpt_embedding_size = self.gpt.transformer.wte.weight.shape[1]
        self.clip_project = Adapter((img_feature_size,
                                       (self.gpt_embedding_size * img_feature_length) // 2,
                                       self.gpt_embedding_size * img_feature_length))
        torch.cuda.empty_cache()
    def get_dummy_token(self,
                        batch_size: int,
                        device: torch.device) -> torch.Tensor:
        return torch.zeros(batch_size, self.img_feature_length, dtype=torch.int64, device=device)

    def forward(self,
                tokens: torch.Tensor,
                feature: torch.Tensor,
                mask = None,
                labels = None):
        torch.cuda.empty_cache()
        gc.collect()

        embedding_text = self.gpt.transformer.wte(tokens)
        feature_projections = self.clip_project(feature).view(-1, self.img_feature_length, self.gpt_embedding_size)
        embedding_cat = torch.cat((feature_projections, embedding_text), dim=1)
        if labels is not None:
            dummy_token = self.get_dummy_token(tokens.shape[0], tokens.device)
            labels = torch.cat((dummy_token, tokens), dim=1)
        out = self.gpt(inputs_embeds=embedding_cat, labels=labels, attention_mask=mask)
        return out

        


def generate_beam(
    model,
    tokenizer,
    beam_size: int = 10,
    prompt=None,
    embed=None,
    entry_length=76,
    temperature=0.9,
    stop_token: str = ".",
):

    model.eval()
    stop_token_index = tokenizer.encode(stop_token)[0]
    tokens = None
    scores = None
    device = next(model.parameters()).device
    seq_lengths = torch.ones(beam_size, device=device)
    is_stopped = torch.zeros(beam_size, device=device, dtype=torch.bool)
    with torch.no_grad():
        if embed is not None:
            generated = embed
        else:
            if tokens is None:
                tokens = torch.tensor(tokenizer.encode(prompt))
                tokens = tokens.unsqueeze(0).to(device)
                generated = model.gpt.transformer.wte(tokens)
        for i in range(entry_length):
            outputs = model.gpt(inputs_embeds=generated)
            logits = outputs.logits
            logits = logits[:, -1, :] / (temperature if temperature > 0 else 1.0)
            logits = logits.softmax(-1).log()
            if scores is None:
                scores, next_tokens = logits.topk(beam_size, -1)
                generated = generated.expand(beam_size, *generated.shape[1:])
                next_tokens, scores = next_tokens.permute(1, 0), scores.squeeze(0)
                if tokens is None:
                    tokens = next_tokens
                else:
                    tokens = tokens.expand(beam_size, *tokens.shape[1:])
                    tokens = torch.cat((tokens, next_tokens), dim=1)
            else:
                logits[is_stopped] = -float(np.inf)
                logits[is_stopped, 0] = 0
                scores_sum = scores[:, None] + logits
                seq_lengths[~is_stopped] += 1
                scores_sum_average = scores_sum / seq_lengths[:, None]
                scores_sum_average, next_tokens = scores_sum_average.view(-1).topk(
                    beam_size, -1
                )
                next_tokens_source = next_tokens // scores_sum.shape[1]
                seq_lengths = seq_lengths[next_tokens_source]
                next_tokens = next_tokens % scores_sum.shape[1]
                next_tokens = next_tokens.unsqueeze(1)
                tokens = tokens[next_tokens_source]
                tokens = torch.cat((tokens, next_tokens), dim=1)
                generated = generated[next_tokens_source]
                scores = scores_sum_average * seq_lengths
                is_stopped = is_stopped[next_tokens_source]
            next_token_embed = model.gpt.transformer.wte(next_tokens.squeeze()).view(
                generated.shape[0], 1, -1
            )
            generated = torch.cat((generated, next_token_embed), dim=1)
            is_stopped = is_stopped + next_tokens.eq(stop_token_index).squeeze()
            if is_stopped.all():
                break
    scores = scores / seq_lengths
    output_list = tokens.cpu().numpy()
    output_texts = [
        tokenizer.decode(output[: int(length)])
        for output, length in zip(output_list, seq_lengths)
    ]
    order = scores.argsort(descending=True)
    output_texts = [output_texts[i] for i in order]
    return output_texts



def generate_caption_clipgpt(img):

    prefix_length = 10
    model = ClipGPT2Model(prefix_length, img_feature_size = feature_dim)
    model.load_state_dict(torch.load('model_train_best_run_clipGPT.pt'))
    model = model.eval()
    device = "cuda" if torch.cuda.is_available() else "cpu"
    model = model.to(device)


    clip_model, preprocess = clip.load('ViT-B/32', device, jit=False)
    tokenizer = GPT2Tokenizer.from_pretrained("gpt2")

    start_time = time.time()
    image = io.imread(img)
    pil_image = PIL.Image.fromarray(image)
    image = preprocess(pil_image).unsqueeze(0).to(device)

    with torch.no_grad():
        prefix = clip_model.encode_image(image).to(device, dtype=torch.float32)
        prefix_embed = model.clip_project(prefix).reshape(1, prefix_length, -1)
        beam_caption = generate_beam(model, tokenizer, embed=prefix_embed)[0]

    end_time = time.time()
    print("--- Time taken to generate: %s seconds ---" % (end_time - start_time))

    return beam_caption