Fine Tune Embedding Model for Advanced Text Analysis

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Posted Nov 12, 2024

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Fine tuning an embedding model is a crucial step in advanced text analysis, allowing you to adapt a pre-trained model to your specific task and dataset.

This process involves updating the model's weights to better fit your data, which can significantly improve its performance.

By fine tuning, you can leverage the knowledge gained from large-scale pre-training, while also incorporating task-specific information from your dataset.

Fine tuning is particularly useful for tasks like sentiment analysis and question answering, where the model needs to understand the nuances of language and context.

Data Preparation

Data Preparation is a crucial step in fine-tuning an embedding model. You'll need to gather and prepare a suitable dataset for training.

The Hugging Face Hub offers many datasets that can be used for fine-tuning embedding models. The enelpol/rag-mini-bioasq dataset is one such example, which includes 4,719 question-answer passages from the BioASQ challenge datasets.

To prepare the dataset, you'll need to load it using the Hugging Face datasets library. This library allows you to easily load and manipulate datasets.

Credit: youtube.com, How To Create Datasets for Finetuning From Multiple Sources! Improving Finetunes With Embeddings.

The dataset format should be a bit different from the expected format for 'Sentence-transformers'. You'll need to select and rename the columns to match the expected format.

Here are some common formats for embedding datasets:

We are going to use the philschmid/finanical-rag-embedding-dataset, which includes 7,000 positive text pairs of questions and corresponding context.

The dataset should be loaded using the 🤗 Datasets library, and the columns should be renamed to match what sentence-transforemrs expects. Then, the dataset should be split into a train and test split to be able to evaluate the model.

To prepare the test data set, you'll need to apply the same steps that you did for the training data.

Embedding Basics

A pre-trained model is a great starting point for fine-tuning embeddings.

To fine-tune embeddings, you'll need to adjust a pre-trained model on your specific dataset. This can significantly improve the model's understanding of context and nuances in your data.

Credit: youtube.com, Fine tuning Embeddings Model

Dataset preparation is key to fine-tuning embeddings. Ensure your dataset is clean and representative of the tasks you want to perform.

Data augmentation techniques can enhance diversity in your dataset. This may involve techniques to add more data to your dataset.

You can utilize frameworks like TensorFlow or PyTorch to implement fine-tuning.

Choosing and Customizing

Choosing the right embedding model is crucial, and it's essential to understand the differences in performance and dimensionality between various options. OpenAI's text-embedding-ada-002 and Google's Vertex AI's textembedding-gecko@001 are two prominent models in the field.

Customizing embeddings for specific applications is key, and it's essential to consider aspects such as the task at hand and the type of data you're working with. This can significantly enhance the performance and relevance of your AI models.

To get started with fine-tuning your embedding model, you'll need to prepare your dataset, ensuring it's clean and representative of the tasks you want to perform. This may involve data augmentation techniques to enhance diversity.

Choosing the Right

Credit: youtube.com, Choosing the right model: Custom build or off the shelf - Sip and Solve

Choosing the right embedding model can be a daunting task, especially with the numerous options available. OpenAI's text-embedding-ada-002 is a prominent model in the field.

The dimensionality of an embedding model can significantly impact the amount of information it stores. This can affect its performance in tasks such as semantic search.

OpenAI's text-embedding-ada-002 and Google's Vertex AI's textembedding-gecko@001 are two models that demonstrate the differences in performance and dimensionality.

Customizing Embeddings for Specific Applications

Customizing Embeddings for Specific Applications is crucial for tailoring AI models to specific needs, enhancing performance and relevance. Embeddings can be customized by considering the following aspects: dimensionality, performance, and the specific application's requirements.

Understanding the differences in performance and dimensionality between various embedding models is essential. For instance, OpenAI's text-embedding-ada-002 and Google's Vertex AI's textembedding-gecko@001 have different dimensionality, which can significantly impact their performance in tasks such as semantic search.

Customizing embeddings involves adjusting a pre-trained model on your specific dataset, a process known as fine-tuning. This can significantly improve the model's understanding of context and nuances in your data.

Credit: youtube.com, "okay, but I want GPT to perform 10x for my specific use case" - Here is how

To illustrate the importance of customizing embeddings, consider the following steps for implementing a semantic search: Document Preparation, Embedding Generation, Query Embedding, and Similarity Search. These steps highlight the need for tailored embeddings that can handle specific application requirements.

Fine-tuning embeddings can be achieved by utilizing frameworks like TensorFlow or PyTorch, as shown in the following code snippet: from transformers import AutoModel, AutoTokenizer; model = AutoModel.from_pretrained('model_name'); tokenizer = AutoTokenizer.from_pretrained('model_name'); # Fine-tuning code goes here.

By considering the specific application's requirements and fine-tuning embeddings, you can create more effective AI models that deliver better results.

Special Tokens

Special Tokens play a crucial role in BERT's classification tasks. They are used to determine the relevance of one sentence to another.

The special [CLS] token is prepended to the beginning of every sentence. It has special significance, as the output of the final transformer layer only uses the first embedding, corresponding to the [CLS] token.

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BERT consists of 12 Transformer layers, and each transformer takes in a list of token embeddings, producing the same number of embeddings on the output. Only the first embedding is used by the classifier.

The BERT paper states, "The first token of every sequence is always a special classification token ([CLS]). The final hidden state corresponding to this token is used as the aggregate sequence representation for classification tasks."

You might think to try some pooling strategy over the final embeddings, but this isn’t necessary. BERT has been trained to only use the [CLS] token for classification, so it has already done the pooling for us!

Here's a quick rundown of the special tokens used in BERT:

  • [CLS]: The special classification token, used as the aggregate sequence representation for classification tasks.
  • [SEP]: The special separator token, used to separate sentences.

Loss Functions and Evaluation

To fine-tune an embedding model, you need to select a loss function based on your dataset format. For Positive Text pairs, you can use the MultipleNegativesRankingLoss in combination with the MatryoshkaLoss.

This approach allows you to leverage the efficiency and flexibility of Matryoshka embeddings, enabling different embedding dimensions to be utilized without significant performance trade-offs.

Credit: youtube.com, Embedding model fine-tuning for RAG systems

The MultipleNegativesRankingLoss is a great loss function if you only have positive pairs as it adds in batch negative samples to the loss function to have per sample n-1 negative samples.

Here are some key metrics to evaluate the performance of your fine-tuned model:

  • Training loss: the error of the model on the training data
  • Validation loss: the error of the model on the validation data
  • Validation token accuracy: the percentage of tokens in the validation set that are correctly predicted by the model

Defining Loss Functions

Defining a loss function is crucial when fine-tuning an embedding model. You use the MultipleNegativesRankingLoss to align with your dataset format, which should consist of positive text pairs.

To determine which loss function to use, take a look at your dataset format information and loss function information. This will help you decide between different loss functions based on your use case.

When fine-tuning embedding models, select a loss function based on your dataset format. For Positive Text pairs, you can use the MultipleNegativesRankingLoss in combination with the MatryoshkaLoss.

This approach enables the use of different embedding dimensions without significant performance trade-offs. The MultipleNegativesRankingLoss is a great loss function if you only have positive pairs, as it adds in batch negative samples to the loss function.

After loading your model, initialize your loss function.

Evaluating Performance

Credit: youtube.com, Loss Functions - EXPLAINED!

Evaluating Performance is a crucial step in fine-tuning your embeddings. To assess the effectiveness of your embeddings in real-world tasks, use metrics such as precision, recall, and F1-score.

The InformationRetrievalEvaluator is a useful tool for evaluating the performance of your embeddings. It calculates various performance metrics, including Mean Reciprocal Rank (MRR), Recall@K, and Normalized Discounted Cumulative Gain (NDCG).

Conducting qualitative evaluations can also provide valuable insights into how your embeddings perform in real-world scenarios. User feedback is essential in continuously improving the model's performance and relevance.

To evaluate the performance of your fine-tuned model, compare it against your baseline model using the same InformationRetrievalEvaluator. This will help you determine the improvement achieved by fine-tuning your model.

Here's a comparison of the performance of the baseline and fine-tuned models:

The fine-tuned model outperforms the baseline model in all dimensions, demonstrating the effectiveness of fine-tuning your embeddings.

BERT and Tokenization

To fine-tune a BERT embedding model, you need to split your text into tokens and map them to their index in the tokenizer vocabulary.

Credit: youtube.com, Understanding BERT Embeddings and Tokenization | NLP | HuggingFace| Data Science | Machine Learning

The tokenization process must be performed by the tokenizer included with BERT, which can be downloaded for use.

We'll be using the "uncased" version of the tokenizer here.

To see the output of tokenization, let's apply the tokenizer to one sentence.

The input format to BERT is over-specified, requiring multiple pieces of information that seem redundant or easily inferred from the data.

BERT requires a specific input format, which includes tokenization and other formatting requirements.

Training and Testing

We train our fine-tuned embedding model using a training loop that consists of a training phase and a validation phase. The training phase involves unpacking data inputs and labels, loading data onto the GPU for acceleration, and clearing out gradients calculated in the previous pass.

In the training phase, we perform a forward pass (feeding input data through the network), a backward pass (backpropagation), and update the network's parameters with the optimizer's step function. We also track variables for monitoring progress.

Credit: youtube.com, Does Fine Tuning Embedding Models Improve RAG?

The validation phase is similar, but we compute the loss on our validation data and track variables for monitoring progress.

To monitor our model's performance, we use a helper function to calculate accuracy and another to format elapsed times as hh:mm:ss.

Here's a summary of the training process:

Notice that the training loss is decreasing, but the validation loss is increasing, suggesting that our model is over-fitting on the training data.

Validation loss is a more precise measure than accuracy, as it takes into account the exact output value, not just which side of a threshold it falls on.

We can also use the Matthews correlation coefficient (MCC) to evaluate our model's performance on the test set, which is the metric used by the wider NLP community to evaluate performance on CoLA.

The MCC score ranges from -1 (worst) to +1 (best), and we can compare our model's score to the expected accuracy of 49.23% for this benchmark.

Fine-Tuning and Optimization

Credit: youtube.com, Fine-Tuning Embeddings for Better Retrieval

Fine-tuning your embedding model is crucial for its performance and relevance. It allows the model to adapt to specific tasks or datasets, enhancing its performance.

To fine-tune embeddings effectively, use a representative dataset that closely resembles the target application. This will help the model learn to recognize patterns and relationships specific to the task at hand.

Regularly retraining embeddings with new data is essential to capture current language trends and ensure relevance. This involves monitoring the performance of embeddings over time and adjusting as necessary.

Here are some key strategies for fine-tuning embeddings:

  • Use a representative dataset that closely resembles the target application.
  • Experiment with different fine-tuning strategies to find the most effective approach.

Installing Hugging Face Library

The Hugging Face Library is a must-have for working with BERT, and installing it is a straightforward process. You can install it by running the transformers package from Hugging Face, which will give you a pytorch interface for working with BERT.

The library contains interfaces for other pretrained language models like OpenAI's GPT and GPT-2, but we've selected the pytorch interface because it strikes a nice balance between high-level APIs and tensorflow code.

Credit: youtube.com, Getting Started With Hugging Face in 15 Minutes | Transformers, Pipeline, Tokenizer, Models

At the moment, the Hugging Face library is the most widely accepted and powerful pytorch interface for working with BERT. It includes pre-built modifications of these models suited to your specific task, such as BertForSequenceClassification.

Using pre-built classes like BertForSequenceClassification simplifies the process of modifying BERT for your purposes. It also includes task-specific classes for token classification, question answering, and next sentence prediction.

run_glue.py is a helpful utility that allows you to pick which GLUE benchmark task you want to run on, and which pre-trained model you want to use. It even supports using 16-bit precision for further speed up.

Unfortunately, all of this configurability comes at the cost of readability. In this Notebook, we've simplified the code greatly and added plenty of comments to make it clear what's going on.

Embeddings

Embeddings are crucial for tailoring AI models to specific applications, enhancing their performance and relevance. They can become outdated as language evolves, leading to poor performance in understanding contemporary language use.

Credit: youtube.com, Embeddings vs Fine Tuning - Part 1, Embeddings

Customizing embeddings involves adjusting a pre-trained model on your specific dataset, which can significantly improve the model's understanding of context and nuances in your data. This process is known as fine-tuning.

Fine-tuning embeddings involves adjusting a pre-trained model on your specific dataset, which can significantly improve the model's understanding of context and nuances in your data. To fine-tune embeddings, you'll need to use a framework like TensorFlow or PyTorch, and implement the fine-tuning code.

Fine-tuning embeddings can be done by following these steps:

Fine-tuning embeddings allows them to adapt to specific tasks or datasets, enhancing their performance. This can be achieved by using a representative dataset that closely resembles the target application.

Regularly retraining embeddings with new data can help capture current language trends and ensure relevance. Monitoring the performance of embeddings over time and adjusting as necessary is also crucial.

Embeddings can become outdated as language evolves, leading to poor performance in understanding contemporary language use. Neglecting the importance of fine-tuning can limit the effectiveness of embeddings.

Training Loop

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The training loop is a crucial part of fine-tuning and optimization. It's where the magic happens, and your model learns to make accurate predictions.

In this loop, we have a training phase and a validation phase. The training phase is where we feed our input data through the network, calculate the loss, and update the model's parameters to minimize the loss. The validation phase is where we evaluate the model's performance on a held-out set of data to prevent overfitting.

Here's a step-by-step breakdown of the training loop:

  • Unpack our data inputs and labels
  • Load data onto the GPU for acceleration
  • Clear out the gradients calculated in the previous pass
  • Forward pass (feed input data through the network)
  • Backward pass (backpropagation)
  • Tell the network to update parameters with optimizer.step()
  • Track variables for monitoring progress

And here's what happens during the validation phase:

  • Unpack our data inputs and labels
  • Load data onto the GPU for acceleration
  • Forward pass (feed input data through the network)
  • Compute loss on our validation data and track variables for monitoring progress

Notice that we're tracking variables to monitor progress, which is essential for fine-tuning and optimization. By keeping an eye on these variables, we can make adjustments to the model and hyperparameters to improve performance.

Credit: youtube.com, Write your training loop in PyTorch

One thing to keep in mind is that validation loss is a more precise measure than accuracy. While accuracy is useful for determining the correct answer, validation loss can catch subtle differences in the output values. This is especially important when working with complex models and datasets.

By paying attention to these details and adjusting our training loop accordingly, we can fine-tune our models and achieve better results.

Learning Rate Scheduler

The Learning Rate Scheduler is a crucial component of fine-tuning and optimization. It helps adjust the learning rate during training to achieve better results.

The authors of the BERT paper recommend choosing from specific learning rate values for Adam optimizer. These values are 5e-5, 3e-5, and 2e-5.

In our example, the learning rate is set to 2e-5. This value is chosen from the recommended list. It's worth noting that the optimal learning rate may vary depending on the specific task and dataset.

Here are the recommended learning rate values for Adam optimizer:

The choice of learning rate can significantly impact the performance of the model. It's essential to experiment with different values to find the optimal one for the specific task.

Saving Loading

Credit: youtube.com, Full Fine tuning with Fewer GPUs - Galore, Optimizer Tricks, Adafactor

Saving and loading a fine-tuned model is a crucial step in the fine-tuning and optimization process. The model and tokenizer can be saved to disk using a script like run_glue.py, which writes them out to disk.

The largest file is the model weights, which is around 418 megabytes. This file size can be substantial, so it's essential to save and load the model efficiently.

To save your model across Colab Notebook sessions, you can download it to your local machine or copy it to your Google Drive. This will allow you to access your model from anywhere and work on it across different sessions.

The model can be loaded back from disk using functions like those described in the run_glue.py script.

Ignoring Bias

Ignoring bias in our models is crucial to ensure fair and accurate results. Regularly evaluating embeddings for bias is a good practice to follow.

Bias can be present in many embeddings, reflecting societal biases in the training data. This can lead to skewed results and reinforce stereotypes.

Credit: youtube.com, Bias in AI and How to Fix It | Runway

To address this, we can use tools designed specifically for bias evaluation. These tools can help us identify and mitigate bias in our models.

Implementing debiasing techniques during the fine-tuning process is another effective approach. This can help reduce the impact of bias in our models and improve overall performance.

Here are some steps we can take to address bias in our models:

  • Regularly evaluate embeddings for bias using tools designed for this purpose.
  • Consider implementing debiasing techniques during the fine-tuning process.

Keith Marchal

Senior Writer

Keith Marchal is a passionate writer who has been sharing his thoughts and experiences on his personal blog for more than a decade. He is known for his engaging storytelling style and insightful commentary on a wide range of topics, including travel, food, technology, and culture. With a keen eye for detail and a deep appreciation for the power of words, Keith's writing has captivated readers all around the world.

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