lavis/models/blip2_models/blip2_t5_instruct.py

"""
 Copyright (c) 2023, salesforce.com, inc.
 All rights reserved.
 SPDX-License-Identifier: BSD-3-Clause
 For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/BSD-3-Clause
"""
import logging
import string
import random
import copy

import torch
import torch.nn as nn
from torch.cuda.amp import autocast as autocast
from transformers import T5TokenizerFast

from lavis.common.registry import registry
from lavis.models.blip2_models.blip2 import Blip2Base, disabled_train
from lavis.models.blip2_models.modeling_t5 import T5Config, T5ForConditionalGeneration
from transformers.modeling_outputs import BaseModelOutput


@registry.register_model("blip2_t5_instruct")
class Blip2T5Instruct(Blip2Base):
    """
    BLIP2 T5 model.
    Supported model types:
        - flant5xl
        - flant5xxl
    Usage:
        >>> from lavis.models import load_model
        >>> model = load_model("blip2_t5_instruct", "flant5xl")
    """

    PRETRAINED_MODEL_CONFIG_DICT = {
        "flant5xl": "configs/models/blip2/blip2_instruct_flant5xl.yaml",
        "flant5xxl": "configs/models/blip2/blip2_instruct_flant5xxl.yaml",
    }

    def __init__(
        self,
        vit_model="eva_clip_g",
        img_size=224,
        drop_path_rate=0,
        use_grad_checkpoint=False,
        vit_precision="fp16",
        freeze_vit=True,
        num_query_token=32,
        t5_model="google/flan-t5-xl",
        prompt="",
        max_txt_len=128,
        max_output_txt_len=256,
        apply_lemmatizer=False,
        num_few_shot_examples=0,
        few_shot_prob=0,
        qformer_text_input=True,
    ):
        """
        apply_lemmatizer: when set to True, postprocess predict_answers() result with lemmas.
        """
        super().__init__()

        self.tokenizer = self.init_tokenizer(truncation_side="left")

        self.visual_encoder, self.ln_vision = self.init_vision_encoder(
            vit_model, img_size, drop_path_rate, use_grad_checkpoint, vit_precision
        )
        if freeze_vit:
            for name, param in self.visual_encoder.named_parameters():
                param.requires_grad = False
            self.visual_encoder = self.visual_encoder.eval()
            self.visual_encoder.train = disabled_train
            logging.info("freeze vision encoder")

        self.Qformer, self.query_tokens = self.init_Qformer(
            num_query_token, self.visual_encoder.num_features
        )

        if not qformer_text_input:
            self.Qformer.bert.embeddings.word_embeddings = None
            self.Qformer.bert.embeddings.position_embeddings = None
            for layer in self.Qformer.bert.encoder.layer:
                layer.output = None
                layer.intermediate = None
        else:
            self.Qformer.resize_token_embeddings(len(self.tokenizer))
        self.Qformer.cls = None

        self.t5_tokenizer = T5TokenizerFast.from_pretrained(t5_model, truncation_side='left')
        self.t5_output_tokenizer = T5TokenizerFast.from_pretrained(t5_model, truncation_side='right')

        t5_config = T5Config.from_pretrained(t5_model)
        t5_config.dense_act_fn = "gelu"
        self.t5_model = T5ForConditionalGeneration.from_pretrained(
            t5_model, config=t5_config
        )

        for name, param in self.t5_model.named_parameters():
            param.requires_grad = False
            param.data = param.data.bfloat16()

        self.t5_proj = nn.Linear(
            self.Qformer.config.hidden_size, self.t5_model.config.hidden_size
        )

        self.max_txt_len = max_txt_len
        self.max_output_txt_len = max_output_txt_len
        self.prompt = prompt

        self._apply_lemmatizer = apply_lemmatizer
        self._lemmatizer = None

        self.num_few_shot_examples = num_few_shot_examples
        self.few_shot_prob = few_shot_prob

        self.qformer_text_input = qformer_text_input

    def forward(self, samples):
        # print('-----------------')
        # print(samples["text_input"])
        # print(samples["text_output"])
        # print('-----------------')

        image = samples["image"]
        with self.maybe_autocast():
            image_embeds = self.ln_vision(self.visual_encoder(image))
        image_atts = torch.ones(image_embeds.size()[:-1], dtype=torch.long).to(image.device)

        query_tokens = self.query_tokens.expand(image_embeds.shape[0], -1, -1)
        if self.qformer_text_input:
            text_Qformer = self.tokenizer(
                samples["text_input"],
                padding='longest',
                truncation=True,
                max_length=self.max_txt_len,
                return_tensors="pt",
            ).to(image.device)
            query_atts = torch.ones(query_tokens.size()[:-1], dtype=torch.long).to(image.device)
            Qformer_atts = torch.cat([query_atts,text_Qformer.attention_mask],dim=1)

            query_output = self.Qformer.bert(
                text_Qformer.input_ids,
                attention_mask=Qformer_atts,
                query_embeds=query_tokens,
                encoder_hidden_states=image_embeds,
                encoder_attention_mask=image_atts,
                return_dict=True,
            )
        else:
            query_output = self.Qformer.bert(
                query_embeds=query_tokens,
                encoder_hidden_states=image_embeds,
                encoder_attention_mask=image_atts,
                return_dict=True,
            )

        inputs_t5 = self.t5_proj(query_output.last_hidden_state[:,:query_tokens.size(1),:])
        atts_t5 = torch.ones(inputs_t5.size()[:-1], dtype=torch.long).to(image.device)

        fs_embeds, fs_atts = None, None
        if self.few_shot_prob > 0 and "few_shot_samples" in samples.keys():
            fs_embeds, fs_atts = self.prepare_few_shot_embeds(samples['few_shot_samples'])

        with self.maybe_autocast(dtype=torch.bfloat16):
            input_tokens = self.t5_tokenizer(
                samples["text_input"],
                padding="longest",
                truncation=True,
                max_length=self.max_txt_len,
                return_tensors="pt",
            ).to(image.device)
            output_tokens = self.t5_output_tokenizer(
                samples["text_output"],
                padding="longest",
                truncation=True,
                max_length=self.max_output_txt_len,
                return_tensors="pt",
            ).to(image.device)

            encoder_atts = torch.cat([atts_t5, input_tokens.attention_mask], dim=1)

            targets = output_tokens.input_ids.masked_fill(
                output_tokens.input_ids == self.t5_tokenizer.pad_token_id, -100
            )

            inputs_embeds = self.t5_model.encoder.embed_tokens(input_tokens.input_ids)
            inputs_embeds = torch.cat([inputs_t5, inputs_embeds], dim=1)

            if fs_embeds is not None:
                inputs_embeds = torch.cat([fs_embeds, inputs_embeds], dim=1)
                encoder_atts = torch.cat([fs_atts, encoder_atts], dim=1)

            outputs = self.t5_model(
                inputs_embeds=inputs_embeds,
                attention_mask=encoder_atts,
                decoder_attention_mask=output_tokens.attention_mask,
                return_dict=True,
                labels=targets,
            )
            loss = outputs.loss

            return {"loss": loss}

    def prepare_few_shot_embeds(self, samples):
        this_n_fs = random.choices(
            list(range(self.num_few_shot_examples + 1)),
            weights=[1 - self.few_shot_prob] + [self.few_shot_prob / self.num_few_shot_examples] * self.num_few_shot_examples
        )[0]

        if this_n_fs == 0:
            return None, None

        images = []
        text_input = []
        for sample in samples:
            for n in range(this_n_fs):
                images.append(sample['image'][n])
                text_input.append(sample['text_input'][n])
        images = torch.stack(images, dim=0)

        image = images

        with self.maybe_autocast():
            image_embeds = self.ln_vision(self.visual_encoder(image))
        image_atts = torch.ones(image_embeds.size()[:-1], dtype=torch.long).to(
            image.device
        )

        query_tokens = self.query_tokens.expand(image_embeds.shape[0], -1, -1)
        if self.qformer_text_input:
            text_Qformer = self.tokenizer(
                text_input,
                padding='longest',
                truncation=True,
                max_length=self.max_txt_len,
                return_tensors="pt",
            ).to(image.device)
            query_atts = torch.ones(query_tokens.size()[:-1], dtype=torch.long).to(image.device)
            Qformer_atts = torch.cat([query_atts,text_Qformer.attention_mask],dim=1)
            query_output = self.Qformer.bert(
                text_Qformer.input_ids,
                attention_mask = Qformer_atts,
                query_embeds=query_tokens,
                encoder_hidden_states=image_embeds,
                encoder_attention_mask=image_atts,
                return_dict=True,
            )
        else:
            query_output = self.Qformer.bert(
                query_embeds=query_tokens,
                encoder_hidden_states=image_embeds,
                encoder_attention_mask=image_atts,
                return_dict=True,
            )

        inputs_t5 = self.t5_proj(query_output.last_hidden_state[:,:query_tokens.size(1),:])
        atts_t5 = torch.ones(inputs_t5.size()[:-1], dtype=torch.long).to(image.device)

        with self.maybe_autocast(dtype=torch.bfloat16):
            input_tokens = self.t5_tokenizer(
                text_input,
                padding="longest",
                truncation=True,
                max_length=self.max_txt_len,
                return_tensors="pt",
            ).to(image.device)

            encoder_atts = torch.cat([atts_t5, input_tokens.attention_mask], dim=1)

            inputs_embeds = self.t5_model.encoder.embed_tokens(input_tokens.input_ids)
            inputs_embeds = torch.cat([inputs_t5, inputs_embeds], dim=1)

        if this_n_fs > 1:
            encoder_atts = encoder_atts.reshape(encoder_atts.size(0) // this_n_fs, encoder_atts.size(1) * this_n_fs)
            inputs_embeds = inputs_embeds.reshape(inputs_embeds.size(0) // this_n_fs, inputs_embeds.size(1) * this_n_fs, inputs_embeds.size(2))

        return inputs_embeds, encoder_atts

    @torch.no_grad()
    def generate(
        self,
        samples,
        use_nucleus_sampling=False,
        num_beams=5,
        max_length=256,
        min_length=1,
        top_p=0.9,
        repetition_penalty=1.5,
        length_penalty=1.0,
        num_captions=1,
        temperature=1,
    ):
        if "prompt" in samples.keys():
            prompt = samples["prompt"]
        else:
            prompt = self.prompt

        image = samples["image"]

        bs = image.size(0)

        if isinstance(prompt, str):
            prompt = [prompt] * bs
        else:
            assert len(prompt) == bs, "The number of prompts must be equal to the batch size."

        # For TextCaps
        if "ocr_tokens" in samples.keys() and "{}" in prompt[0]:
            prompt = [p.format(', '.join(samples['ocr_tokens'][i][:30])) for i, p in enumerate(prompt)]

        query_tokens = self.query_tokens.expand(bs, -1, -1)
        if self.qformer_text_input:
            # remove ocr tokens in q_former (for eval textvqa)
            # qformer_prompt = prompt
            # qformer_prompt = ['Question: ' + qp.split(' Question: ')[1] for qp in qformer_prompt]

            text_Qformer = self.tokenizer(
                prompt,
                padding='longest',
                truncation=True,
                max_length=self.max_txt_len,
                return_tensors="pt",
            ).to(image.device)
            query_atts = torch.ones(query_tokens.size()[:-1], dtype=torch.long).to(image.device)
            Qformer_atts = torch.cat([query_atts,text_Qformer.attention_mask],dim=1)

        # For video data
        if image.dim() == 5:
            inputs_t5, atts_t5 = [], []
            for j in range(image.size(2)):
                this_frame = image[:,:,j,:,:]
                with self.maybe_autocast():
                    frame_embeds = self.ln_vision(self.visual_encoder(this_frame))
                    frame_atts = torch.ones(frame_embeds.size()[:-1], dtype=torch.long).to(image.device)

                if self.qformer_text_input:
                    frame_query_output = self.Qformer.bert(
                        text_Qformer.input_ids,
                        attention_mask = Qformer_atts,
                        query_embeds=query_tokens,
                        encoder_hidden_states=frame_embeds,
                        encoder_attention_mask=frame_atts,
                        return_dict=True,
                    )
                else:
                    frame_query_output = self.Qformer.bert(
                        query_embeds=query_tokens,
                        encoder_hidden_states=frame_embeds,
                        encoder_attention_mask=frame_atts,
                        return_dict=True,
                    )

                frame_inputs_t5 = self.t5_proj(frame_query_output.last_hidden_state[:,:query_tokens.size(1),:])
                frame_atts_t5 = torch.ones(frame_inputs_t5.size()[:-1], dtype=torch.long).to(image.device)
                inputs_t5.append(frame_inputs_t5)
                atts_t5.append(frame_atts_t5)
            inputs_t5 = torch.cat(inputs_t5, dim=1)
            atts_t5 = torch.cat(atts_t5, dim=1)
        else:
            with self.maybe_autocast():
                image_embeds = self.ln_vision(self.visual_encoder(image))
            image_atts = torch.ones(image_embeds.size()[:-1], dtype=torch.long).to(image.device)

            if self.qformer_text_input:
                query_output = self.Qformer.bert(
                    text_Qformer.input_ids,
                    attention_mask=Qformer_atts,
                    query_embeds=query_tokens,
                    encoder_hidden_states=image_embeds,
                    encoder_attention_mask=image_atts,
                    return_dict=True,
                )
            else:
                query_output = self.Qformer.bert(
                    query_embeds=query_tokens,
                    encoder_hidden_states=image_embeds,
                    encoder_attention_mask=image_atts,
                    return_dict=True,
                )

            inputs_t5 = self.t5_proj(query_output.last_hidden_state[:,:query_tokens.size(1),:])
            atts_t5 = torch.ones(inputs_t5.size()[:-1], dtype=torch.long).to(image.device)

        input_tokens = self.t5_tokenizer(
            prompt,
            padding="longest",
            return_tensors="pt"
        ).to(image.device)

        encoder_atts = torch.cat([atts_t5, input_tokens.attention_mask], dim=1)

        with self.maybe_autocast(dtype=torch.bfloat16):
            inputs_embeds = self.t5_model.encoder.embed_tokens(input_tokens.input_ids)
            inputs_embeds = torch.cat([inputs_t5, inputs_embeds], dim=1)

            outputs = self.t5_model.generate(
                inputs_embeds=inputs_embeds,
                attention_mask=encoder_atts,
                do_sample=use_nucleus_sampling,
                top_p=top_p,
                temperature=temperature,
                num_beams=num_beams,
                max_new_tokens=max_length,
                min_length=min_length,
                repetition_penalty=repetition_penalty,
                length_penalty=length_penalty,
                num_return_sequences=num_captions,
            )
            output_text = self.t5_tokenizer.batch_decode(
                outputs, skip_special_tokens=True
            )

        return output_text

    def predict_answers(
        self,
        samples,
        num_beams=5,
        inference_method="generate",
        max_len=10,
        min_len=1,
        num_ans_candidates=128,
        answer_list=None,
        prompt="",
        length_penalty=-1,
        **kwargs
    ):
        if isinstance(samples["text_input"], str):
            samples["text_input"] = [samples["text_input"]]

        if prompt:
            if prompt.count("{}") == 2:
                if 'ocr_tokens' in samples:
                    text_input = [
                        prompt.format(', '.join(samples['ocr_tokens'][i][:30]), samples["text_input"][i])
                    for i in range(len(samples["text_input"]))]
                elif 'choices' in samples:
                    text_input = []
                    for i in range(len(samples["text_input"])):
                        this_choices = [f"({string.ascii_lowercase[j]}) {ch}" for j, ch in enumerate(samples["choices"][i])]
                        this_choices = " ".join(this_choices)
                        text_input.append(prompt.format(samples["text_input"][i], this_choices))
            else:
                text_input = [prompt.format(question) for question in samples["text_input"]]
        else:
            text_input = samples["text_input"]

        samples["prompt"] = text_input

        output_text = self.generate(
            samples,
            num_beams=num_beams,
            max_length=max_len,
            min_length=min_len,
            length_penalty=length_penalty
        )

        if self._apply_lemmatizer or ("apply_lemmatizer" in samples.keys() and samples["apply_lemmatizer"]):
            output_text = self._lemmatize(output_text)

        return output_text

    def predict_class(
        self,
        samples,
        candidates,
        n_segments=1,
    ):
        # If candidates is a list of lists, each sample has its candidates, then we need to iterate one by one
        if type(candidates[0]) == list:
            results = []

            for i in range(samples["image"].size(0)):
                this_sample = {
                    "image": samples["image"][i].unsqueeze(0),
                    "prompt": samples["prompt"],
                }

                if "text_input" in samples.keys():
                    this_sample["text_input"] = [samples["text_input"][i]]

                if 'context' in samples.keys():
                    this_sample['context'] = [samples["context"][i]]

                if 'history' in samples.keys():
                    this_sample['history'] = [samples["history"][i]]

                if 'caption' in samples.keys():
                    this_sample['caption'] = [samples["caption"][i]]

                this_result = self._predict_class(this_sample, candidates[i], n_segments)
                results.append(this_result)

            try:
                results = torch.cat(results, dim=0)
            except:
                results = [res.tolist()[0] for res in results]

            return results

        return self._predict_class(samples, candidates, n_segments)

    def _predict_class(
        self,
        samples,
        candidates,
        n_segments=1,
    ):
        """
        Args:
            samples (dict): A dictionary containing the following keys:
                - image (torch.Tensor): A tensor of shape (batch_size, 3, H, W)
                - prompt: the instruction
            candidates:
                (list): A list of candidate class names;
            n_segments:
                (int): Split the candidates into n_segments and predict one by one. This is useful when the number of candidates is too large.
        Returns:
            output_class: predicted class index
        """

        image = samples["image"]
        prompt = samples["prompt"]

        bs = image.size(0)

        if isinstance(prompt, str):
            prompt = [prompt] * bs
        else:
            assert len(prompt) == bs, "The number of prompts must be equal to the batch size."

        if "text_input" in samples.keys():
            if type(samples["text_input"][0]) == list:
                prompt = [prompt[i].format(*samples["text_input"][i]) for i in range(len(prompt))]
            else:
                prompt = [prompt[i].format(samples["text_input"][i]) for i in range(len(prompt))]

        # scienceqa
        if 'context' in samples.keys() and samples['context'] != '':
            prompt = [f'context: {samples["context"][i]}. {prompt[i]}' for i in range(len(prompt))]

        # visual dialog
        if 'history' in samples.keys() and samples['history'][0] != '':
            prompt = [f'dialog history: {samples["history"][i]}\n{prompt[i]}' for i in range(len(prompt))]

        if 'caption' in samples.keys() and samples['caption'][0] != '':
            prompt = [f'This image has the caption "{samples["caption"][i]}". {prompt[i]}' for i in range(len(prompt))]

        query_tokens = self.query_tokens.expand(bs, -1, -1)
        if self.qformer_text_input:
            text_Qformer = self.tokenizer(
                prompt,
                padding='longest',
                truncation=True,
                max_length=self.max_txt_len,
                return_tensors="pt"
            ).to(image.device)
            query_atts = torch.ones(query_tokens.size()[:-1], dtype=torch.long).to(image.device)
            Qformer_atts = torch.cat([query_atts,text_Qformer.attention_mask], dim=1)

        if image.dim() == 5:
            inputs_t5, atts_t5 = [], []
            for j in range(image.size(2)):
                this_frame = image[:,:,j,:,:]
                with self.maybe_autocast():
                    frame_embeds = self.ln_vision(self.visual_encoder(this_frame))
                    frame_atts = torch.ones(frame_embeds.size()[:-1], dtype=torch.long).to(image.device)

                if self.qformer_text_input:
                    frame_query_output = self.Qformer.bert(
                        text_Qformer.input_ids,
                        attention_mask=Qformer_atts,
                        query_embeds=query_tokens,
                        encoder_hidden_states=frame_embeds,
                        encoder_attention_mask=frame_atts,
                        return_dict=True,
                    )
                else:
                    frame_query_output = self.Qformer.bert(
                        query_embeds=query_tokens,
                        encoder_hidden_states=frame_embeds,
                        encoder_attention_mask=frame_atts,
                        return_dict=True,
                    )

                frame_inputs_t5 = self.t5_proj(frame_query_output.last_hidden_state[:,:query_tokens.size(1),:])
                frame_atts_t5 = torch.ones(frame_inputs_t5.size()[:-1], dtype=torch.long).to(image.device)
                inputs_t5.append(frame_inputs_t5)
                atts_t5.append(frame_atts_t5)
            inputs_t5 = torch.cat(inputs_t5, dim=1)
            atts_t5 = torch.cat(atts_t5, dim=1)
        else:
            with self.maybe_autocast():
                image_embeds = self.ln_vision(self.visual_encoder(image))
            image_atts = torch.ones(image_embeds.size()[:-1], dtype=torch.long).to(image.device)

            if self.qformer_text_input:
                query_output = self.Qformer.bert(
                    text_Qformer.input_ids,
                    attention_mask=Qformer_atts,
                    query_embeds=query_tokens,
                    encoder_hidden_states=image_embeds,
                    encoder_attention_mask=image_atts,
                    return_dict=True,
                )
            else:
                query_output = self.Qformer.bert(
                    query_embeds=query_tokens,
                    encoder_hidden_states=image_embeds,
                    encoder_attention_mask=image_atts,
                    return_dict=True,
                )

            inputs_t5 = self.t5_proj(query_output.last_hidden_state[:,:query_tokens.size(1),:])
            atts_t5 = torch.ones(inputs_t5.size()[:-1], dtype=torch.long).to(image.device)

        input_tokens = self.t5_tokenizer(
            prompt, padding="longest", return_tensors="pt"
        ).to(image.device)
        output_tokens = self.t5_tokenizer(
            candidates, padding="longest", return_tensors="pt"
        ).to(image.device)

        encoder_atts = torch.cat([atts_t5, input_tokens.attention_mask], dim=1)

        n_cands = len(candidates)

        with self.maybe_autocast(dtype=torch.bfloat16):
            inputs_embeds = self.t5_model.encoder.embed_tokens(input_tokens.input_ids)
            inputs_embeds = torch.cat([inputs_t5, inputs_embeds], dim=1)

            encoder_outputs = self.t5_model.encoder(
                inputs_embeds=inputs_embeds,
                attention_mask=encoder_atts,
            )

            all_losses = []
            for n in range(n_segments):
                seg_len = n_cands // n_segments
                if n == (n_segments - 1):
                    seg_len = n_cands - seg_len * (n_segments - 1)

                # this_encoder_outputs = copy.deepcopy(encoder_outputs)
                this_encoder_outputs = BaseModelOutput(
                    last_hidden_state=encoder_outputs[0].clone(),
                )

                this_encoder_outputs['last_hidden_state'] = this_encoder_outputs[0].repeat_interleave(seg_len, dim=0)
                this_encoder_atts = encoder_atts.repeat_interleave(seg_len, dim=0)

                start_i = n * (n_cands // n_segments)
                end_i = start_i + seg_len
                this_output_tokens_ids = output_tokens.input_ids[start_i:end_i].repeat(bs, 1)
                this_output_tokens_atts = output_tokens.attention_mask[start_i:end_i].repeat(bs, 1)

                this_targets = this_output_tokens_ids.masked_fill(this_output_tokens_ids == self.t5_tokenizer.pad_token_id, -100)

                outputs = self.t5_model(
                    encoder_outputs=this_encoder_outputs,
                    attention_mask=this_encoder_atts,
                    decoder_attention_mask=this_output_tokens_atts,
                    return_dict=True,
                    labels=this_targets,
                    reduction="none",
                )
                loss = outputs.loss

                loss = loss.reshape(bs, seg_len)
                # output_class_ranks = torch.argsort(loss, dim=-1)
                all_losses.append(loss)

            all_losses = torch.cat(all_losses, dim=-1)
            output_class_ranks = torch.argsort(all_losses, dim=-1)

            # encoder_outputs['last_hidden_state'] = encoder_outputs[0].repeat_interleave(n_cands, dim=0)
            # encoder_atts = encoder_atts.repeat_interleave(n_cands, dim=0)
            # output_tokens.input_ids = output_tokens.input_ids.repeat(bs, 1)
            # output_tokens.attention_mask = output_tokens.attention_mask.repeat(bs, 1)

            # # compute the LM loss for each candidate (sum logprob across all tokens) and select the highest
            # targets = output_tokens.input_ids.masked_fill(output_tokens.input_ids == self.t5_tokenizer.pad_token_id, -100)

            # outputs = self.t5_model(
            #     encoder_outputs=encoder_outputs,
            #     attention_mask=encoder_atts,
            #     decoder_attention_mask=output_tokens.attention_mask,
            #     return_dict=True,
            #     labels=targets,
            #     reduction="none",
            # )
            # loss = outputs.loss

            # loss = loss.reshape(bs, n_cands)
            # output_class_ranks = torch.argsort(loss, dim=-1) # (bs, num_candidates)

        return output_class_ranks

    def _lemmatize(self, answers):
        def apply(answer):
            doc = self.lemmatizer(answer)

            words = []
            for token in doc:
                if token.pos_ in ["NOUN", "VERB"]:
                    words.append(token.lemma_)
                else:
                    words.append(token.text)
            answer = " ".join(words)

            return answer

        return [apply(answer) for answer in answers]

    @property
    def lemmatizer(self):
        if self._lemmatizer is None:
            try:
                import spacy

                self._lemmatizer = spacy.load("en_core_web_sm")
            except ImportError:
                logging.error(
                    """
                    Please install spacy and en_core_web_sm model to apply lemmatization.
                    python -m spacy download en_core_web_sm
                    OR
                    import spacy.cli
                    spacy.cli.download("en_core_web_sm")
                    """
                )
                exit(1)

        return self._lemmatizer

    @classmethod
    def from_config(cls, cfg):
        vit_model = cfg.get("vit_model", "eva_clip_g")
        img_size = cfg.get("image_size")
        num_query_token = cfg.get("num_query_token")
        t5_model = cfg.get("t5_model")

        drop_path_rate = cfg.get("drop_path_rate", 0)
        use_grad_checkpoint = cfg.get("use_grad_checkpoint", False)
        vit_precision = cfg.get("vit_precision", "fp16")
        freeze_vit = cfg.get("freeze_vit", True)

        prompt = cfg.get("prompt", "")
        max_txt_len = cfg.get("max_txt_len", 128)
        max_output_txt_len = cfg.get("max_output_txt_len", 256)

        apply_lemmatizer = cfg.get("apply_lemmatizer", False)

        num_few_shot_examples = cfg.get("num_few_shot_examples", 0)
        few_shot_prob = cfg.get("few_shot_prob", 0.0)

        qformer_text_input = cfg.get("qformer_text_input", True)

        model = cls(
            vit_model=vit_model,
            img_size=img_size,
            drop_path_rate=drop_path_rate,
            use_grad_checkpoint=use_grad_checkpoint,
            vit_precision=vit_precision,
            freeze_vit=freeze_vit,
            num_query_token=num_query_token,
            t5_model=t5_model,
            prompt=prompt,
            max_txt_len=max_txt_len,
            max_output_txt_len=max_output_txt_len,
            apply_lemmatizer=apply_lemmatizer,
            num_few_shot_examples=num_few_shot_examples,
            few_shot_prob=few_shot_prob,
            qformer_text_input=qformer_text_input,
        )

        # if qformer_text_input:
        #     # Hard-coded to load from BLIP-2 stage-1 pre-trained model (not ideal)
        #     model.load_from_pretrained(
        #         url_or_filename="https://storage.googleapis.com/sfr-vision-language-research/LAVIS/models/BLIP2/blip2_pretrained.pth"
        #     )

        model.load_checkpoint_from_config(cfg)

        return model