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metadata
language: en
license: mit
tags:
  - keyphrase-extraction
datasets:
  - midas/inspec
metrics:
  - seqeval
widget:
  - text: >-
      Keyphrase extraction is a technique in text analysis where you extract the
      important keyphrases from a document.  Thanks to these keyphrases humans
      can understand the content of a text very quickly and easily without
      reading  it completely. Keyphrase extraction was first done primarily by
      human annotators, who read the text in detail  and then wrote down the
      most important keyphrases. The disadvantage is that if you work with a lot
      of documents,  this process can take a lot of time. 

      Here is where Artificial Intelligence comes in. Currently, classical
      machine learning methods, that use statistical  and linguistic features,
      are widely used for the extraction process. Now with deep learning, it is
      possible to capture  the semantic meaning of a text even better than these
      classical methods. Classical methods look at the frequency,  occurrence
      and order of words in the text, whereas these neural approaches can
      capture long-term semantic dependencies  and context of words in a text.
    example_title: Example 1
  - text: >-
      In this work, we explore how to learn task specific language models aimed
      towards learning rich representation of keyphrases from text documents. We
      experiment with different masking strategies for pre-training transformer
      language models (LMs) in discriminative as well as generative settings. In
      the discriminative setting, we introduce a new pre-training objective -
      Keyphrase Boundary Infilling with Replacement (KBIR), showing large gains
      in performance (up to 9.26 points in F1) over SOTA, when LM pre-trained
      using KBIR is fine-tuned for the task of keyphrase extraction. In the
      generative setting, we introduce a new pre-training setup for BART -
      KeyBART, that reproduces the keyphrases related to the input text in the
      CatSeq format, instead of the denoised original input. This also led to
      gains in performance (up to 4.33 points inF1@M) over SOTA for keyphrase
      generation. Additionally, we also fine-tune the pre-trained language
      models on named entity recognition(NER), question answering (QA), relation
      extraction (RE), abstractive summarization and achieve comparable
      performance with that of the SOTA, showing that learning rich
      representation of keyphrases is indeed beneficial for many other
      fundamental NLP tasks.
    example_title: Example 2
model-index:
  - name: DeDeckerThomas/keyphrase-extraction-distilbert-inspec
    results:
      - task:
          type: keyphrase-extraction
          name: Keyphrase Extraction
        dataset:
          type: midas/inspec
          name: inspec
        metrics:
          - type: F1 (Seqeval)
            value: 0.509
            name: F1 (Seqeval)
          - type: F1@M
            value: 0.49
            name: F1@M

πŸ”‘ Keyphrase Extraction Model: distilbert-inspec

Keyphrase extraction is a technique in text analysis where you extract the important keyphrases from a document. Thanks to these keyphrases humans can understand the content of a text very quickly and easily without reading it completely. Keyphrase extraction was first done primarily by human annotators, who read the text in detail and then wrote down the most important keyphrases. The disadvantage is that if you work with a lot of documents, this process can take a lot of time ⏳.

Here is where Artificial Intelligence πŸ€– comes in. Currently, classical machine learning methods, that use statistical and linguistic features, are widely used for the extraction process. Now with deep learning, it is possible to capture the semantic meaning of a text even better than these classical methods. Classical methods look at the frequency, occurrence and order of words in the text, whereas these neural approaches can capture long-term semantic dependencies and context of words in a text.

πŸ““ Model Description

This model uses distilbert as its base model and fine-tunes it on the Inspec dataset.

Keyphrase extraction models are transformer models fine-tuned as a token classification problem where each word in the document is classified as being part of a keyphrase or not.

Label Description
B-KEY At the beginning of a keyphrase
I-KEY Inside a keyphrase
O Outside a keyphrase

Kulkarni, Mayank, Debanjan Mahata, Ravneet Arora, and Rajarshi Bhowmik. "Learning Rich Representation of Keyphrases from Text." arXiv preprint arXiv:2112.08547 (2021).

Sahrawat, Dhruva, Debanjan Mahata, Haimin Zhang, Mayank Kulkarni, Agniv Sharma, Rakesh Gosangi, Amanda Stent, Yaman Kumar, Rajiv Ratn Shah, and Roger Zimmermann. "Keyphrase extraction as sequence labeling using contextualized embeddings." In European Conference on Information Retrieval, pp. 328-335. Springer, Cham, 2020.

βœ‹ Intended Uses & Limitations

πŸ›‘ Limitations

  • This keyphrase extraction model is very domain-specific and will perform very well on abstracts of scientific papers. It's not recommended to use this model for other domains, but you are free to test it out.
  • Only works for English documents.
  • For a custom model, please consult the training notebook for more information.

❓ How to use

from transformers import (
    TokenClassificationPipeline,
    AutoModelForTokenClassification,
    AutoTokenizer,
)
from transformers.pipelines import AggregationStrategy
import numpy as np

# Define keyphrase extraction pipeline
class KeyphraseExtractionPipeline(TokenClassificationPipeline):
    def __init__(self, model, *args, **kwargs):
        super().__init__(
            model=AutoModelForTokenClassification.from_pretrained(model),
            tokenizer=AutoTokenizer.from_pretrained(model),
            *args,
            **kwargs
        )

    def postprocess(self, model_outputs):
        results = super().postprocess(
            model_outputs=model_outputs,
            aggregation_strategy=AggregationStrategy.FIRST,
        )
        return np.unique([result.get("word").strip() for result in results])
# Load pipeline
model_name = "ml6team/keyphrase-extraction-distilbert-inspec"
extractor = KeyphraseExtractionPipeline(model=model_name)
# Inference
text = """
Keyphrase extraction is a technique in text analysis where you extract the
important keyphrases from a document. Thanks to these keyphrases humans can
understand the content of a text very quickly and easily without reading it
completely. Keyphrase extraction was first done primarily by human annotators,
who read the text in detail and then wrote down the most important keyphrases.
The disadvantage is that if you work with a lot of documents, this process
can take a lot of time. 

Here is where Artificial Intelligence comes in. Currently, classical machine
learning methods, that use statistical and linguistic features, are widely used
for the extraction process. Now with deep learning, it is possible to capture
the semantic meaning of a text even better than these classical methods.
Classical methods look at the frequency, occurrence and order of words
in the text, whereas these neural approaches can capture long-term
semantic dependencies and context of words in a text.
""".replace("\n", " ")

keyphrases = extractor(text)

print(keyphrases)
# Output
['artificial intelligence' 'classical machine learning' 'deep learning'
 'keyphrase extraction' 'linguistic features' 'statistical'
 'text analysis']

πŸ“š Training Dataset

Inspec is a keyphrase extraction/generation dataset consisting of 2000 English scientific papers from the scientific domains of Computers and Control and Information Technology published between 1998 to 2002. The keyphrases are annotated by professional indexers or editors.

You can find more information in the paper.

πŸ‘·β€β™‚οΈ Training Procedure

For more in detail information, you can take a look at the training notebook (link incoming).

Training Parameters

Parameter Value
Learning Rate 1e-4
Epochs 50
Early Stopping Patience 3

Preprocessing

The documents in the dataset are already preprocessed into list of words with the corresponding labels. The only thing that must be done is tokenization and the realignment of the labels so that they correspond with the right subword tokens.

from datasets import load_dataset
from transformers import AutoTokenizer

# Labels
label_list = ["B", "I", "O"]
lbl2idx = {"B": 0, "I": 1, "O": 2}
idx2label = {0: "B", 1: "I", 2: "O"}

# Tokenizer
tokenizer = AutoTokenizer.from_pretrained("distilbert-base-uncased", add_prefix_space=True)
max_length = 512

# Dataset parameters
dataset_full_name = "midas/inspec"
dataset_subset = "raw"
dataset_document_column = "document"
dataset_biotags_column = "doc_bio_tags"

def preprocess_fuction(all_samples_per_split):
    tokenized_samples = tokenizer.batch_encode_plus(
        all_samples_per_split[dataset_document_column],
        padding="max_length",
        truncation=True,
        is_split_into_words=True,
        max_length=max_length,
    )
    total_adjusted_labels = []
    for k in range(0, len(tokenized_samples["input_ids"])):
        prev_wid = -1
        word_ids_list = tokenized_samples.word_ids(batch_index=k)
        existing_label_ids = all_samples_per_split[dataset_biotags_column][k]
        i = -1
        adjusted_label_ids = []

        for wid in word_ids_list:
            if wid is None:
                adjusted_label_ids.append(lbl2idx["O"])
            elif wid != prev_wid:
                i = i + 1
                adjusted_label_ids.append(lbl2idx[existing_label_ids[i]])
                prev_wid = wid
            else:
                adjusted_label_ids.append(
                    lbl2idx[
                        f"{'I' if existing_label_ids[i] == 'B' else existing_label_ids[i]}"
                    ]
                )

        total_adjusted_labels.append(adjusted_label_ids)
    tokenized_samples["labels"] = total_adjusted_labels
    return tokenized_samples

# Load dataset
dataset = load_dataset(dataset_full_name, dataset_subset)

# Preprocess dataset
tokenized_dataset = dataset.map(preprocess_fuction, batched=True)
    

Postprocessing (Without Pipeline Function)

If you do not use the pipeline function, you must filter out the B and I labeled tokens. Each B and I will then be merged into a keyphrase. Finally, you need to strip the keyphrases to make sure all unnecessary spaces have been removed.

# Define post_process functions
def concat_tokens_by_tag(keyphrases):
    keyphrase_tokens = []
    for id, label in keyphrases:
        if label == "B":
            keyphrase_tokens.append([id])
        elif label == "I":
            if len(keyphrase_tokens) > 0:
                keyphrase_tokens[len(keyphrase_tokens) - 1].append(id)
    return keyphrase_tokens


def extract_keyphrases(example, predictions, tokenizer, index=0):
    keyphrases_list = [
        (id, idx2label[label])
        for id, label in zip(
            np.array(example["input_ids"]).squeeze().tolist(), predictions[index]
        )
        if idx2label[label] in ["B", "I"]
    ]

    processed_keyphrases = concat_tokens_by_tag(keyphrases_list)
    extracted_kps = tokenizer.batch_decode(
        processed_keyphrases,
        skip_special_tokens=True,
        clean_up_tokenization_spaces=True,
    )
    return np.unique([kp.strip() for kp in extracted_kps])

πŸ“ Evaluation results

Traditional evaluation methods are the precision, recall and F1-score @k,m where k is the number that stands for the first k predicted keyphrases and m for the average amount of predicted keyphrases. The model achieves the following results on the Inspec test set:

Dataset P@5 R@5 F1@5 P@10 R@10 F1@10 P@M R@M F1@M
Inspec Test Set 0.45 0.40 0.39 0.33 0.53 0.38 0.47 0.57 0.49

For more information on the evaluation process, you can take a look at the keyphrase extraction evaluation notebook.

🚨 Issues

Please feel free to start discussions in the Community Tab.