🔸 A-TE-2: Building an NLP Pipeline - Recommender Systems

Building an NLP Pipeline: Recommender Systems

Advanced Track - Tech-Driven AI Explorations

This project has been selected for expansion into 2024 virtual-internships. Interested? Apply here.


This advanced project focuses on building a robust NLP pipeline to develop recommender systems using state-of-the-art embedding techniques. Participants will convert textual data into numerical representations using OpenAI’s embedding APIs and advanced Python libraries, creating sophisticated recommender systems that leverage these embeddings.

Learning Outcomes

Participants will:

  • Master the construction and application of NLP pipelines for recommender systems.
  • Explore various text embedding methods including word2vec, GloVe, and BERT.
  • Employ OpenAI’s Embedding APIs and advanced machine learning models to enhance recommender system functionalities.
  • Develop skills in evaluating recommender systems using metrics such as Accuracy, Precision, Recall, and F1-Score.

Pre-requisite Skills

  • Intermediate proficiency in Python programming.
  • Basic knowledge of NLP and machine learning concepts.

Skills Gained

  • Advanced techniques in building NLP pipelines for recommender systems.
  • Implementation of complex text embeddings.
  • Development and evaluation of recommender systems.
  • Utilization of Python libraries and OpenAI APIs in practical applications.

Tools Explored

  • OpenAI Embedding API
  • Python libraries such as Pandas, Scikit-Learn
  • BERT and other transformer models
  • Word2Vec and GloVe embeddings
  • PyTorch for implementing deep learning models

Steps and Tasks

At any point during your project, if you find yourself needing assistance, several resources are available to support you:

  • Code Snippets: Code snippets for each step are shared in the next section.
  • Code-Along Discussion Category: Join discussions to exchange ideas and resolve issues.
  • STEM-Away Mentorship Category: For paid members, access live mentorship, including forum support and webinars, to enhance your learning experience.

Conceptual Understanding

Begin with the curated list in Text Classification using NLP. Delve deeper into recommender systems through:

1. Setup and Data Preparation

  • Install Essential Python Libraries: Begin by installing all necessary Python libraries required for data manipulation and deep learning. Ensure you have libraries such as Pandas, Scikit-Learn, and TensorFlow or PyTorch installed.

  • Download and Preprocess the MovieLens Dataset: Utilize this popular dataset to build and test recommender systems. It offers extensive user-movie interaction data which you will preprocess to facilitate embedding and model training. Conduct an initial exploratory data analysis to understand the dataset’s structure and key features.

2. Embedding the Data

  • Basic Embedding with OpenAI API: Utilize OpenAI’s Embedding API to transform textual movie descriptions into high-dimensional vectors. This approach is straightforward and suitable for beginners.

  • Advanced Option Using Pre-trained Models: For a more in-depth exploration, use pre-trained models like BERT or GPT to generate embeddings. This method allows for richer textual understanding and can lead to more nuanced recommendations.

For detailed guidance on embeddings, please refer to Text Classification using NLP.

3. Developing the Recommender System

  • Basic Recommender System Using Cosine Similarity: Implement a simple recommendation model by calculating cosine similarity between movie embeddings. This method is computationally efficient and easy to understand.

Here are the five most beginner-friendly techniques for building a text recommendation system, along with brief explanations and resources for further learning. Remember that it’s important to understand your specific problem and dataset to choose the best method.

  • Cosine Similarity

    It measures the cosine of the angle between two vectors. The cosine similarity is advantageous because even if the two similar documents are far apart by the Euclidean distance (due to the size of the document), they could still have a smaller angle between them.
    Cosine Similarity - Understanding the math and how it works (with python codes)

  • Euclidean Distance

    It’s the “ordinary” straight-line distance between two points in Euclidean space. With text data, documents are converted into vectors, and the Euclidean distance between them represents how similar those documents are. You can also use Manhattan Distance.
    Euclidean Distance in Python
    Manhattan Distance in Python

  • Jaccard Similarity

    It’s used for comparing the similarity and diversity of sample sets. The Jaccard coefficient measures similarity between finite sample sets and is defined as the size of the intersection divided by the size of the union of the sample sets.
    Understanding the Jaccard Similarity Coefficient

  • TF-IDF (Term Frequency-Inverse Document Frequency)

    This reflects how important a word is to a document in a collection or corpus. It’s often used as a weighting factor in searches of information retrieval, text mining, and user modeling.
    TF-IDF from Scratch in Python on Real World Dataset

  • Intermediate Approach Using Machine Learning: Employ machine learning techniques such as k-nearest neighbors (KNN) to recommend movies. This approach uses the embeddings as features for the ML model.

  • Advanced Deep Learning Models: Construct a neural network that can learn to predict user preferences based on the embeddings. This method involves more complex data handling and model training but can potentially improve recommendation accuracy.

4. Model Evaluation and Refinement

  • Set Up Evaluation Metrics: Use metrics such as Precision, Recall, and F1-Score to assess the effectiveness of your recommender system.

  • Iterative Testing and Tuning: Continuously test the model against a validation set and tune hyperparameters to improve performance. For advanced paths, consider using techniques like grid search or random search to optimize settings.

  • Performance Analysis: Analyze the model’s performance on unseen data to ensure that it generalizes well and provides relevant recommendations.


1. Setup and Data Preparation

# Install necessary libraries
!pip install numpy pandas scikit-learn tensorflow gensim openai

# Import libraries
import pandas as pd
import numpy as np
from sklearn.model_selection import train_test_split
from sklearn.preprocessing import StandardScaler
import openai

# Load and preprocess the MovieLens dataset
movielens_data = pd.read_csv('path/to/movielens.csv')

# Basic data preprocessing
movielens_data['userId'] = movielens_data['userId'].astype(str)
movielens_data['movieId'] = movielens_data['movieId'].astype(str)

# Split data into training and testing sets
train_data, test_data = train_test_split(movielens_data, test_size=0.2, random_state=42)

2. Embedding the Data

# Basic embedding with OpenAI API
openai.api_key = 'your-api-key'

def get_embedding(text):
    response = openai.Embedding.create(input=[text], model="text-embedding-ada-002")
    return response['data'][0]['embedding']

# Example: Get embedding for a movie description
movie_description = "A young wizard's journey to defeat the dark forces."
embedding = get_embedding(movie_description)

3a. Developing the Recommender System (Cosine Similarity)

# Basic recommender system using cosine similarity
from sklearn.metrics.pairwise import cosine_similarity

# Assume embeddings_df is a DataFrame with movieId and corresponding embeddings
def recommend_movies(movie_id, embeddings_df, top_n=5):
    movie_embedding = embeddings_df.loc[embeddings_df['movieId'] == movie_id, 'embedding'].values[0]
    similarities = cosine_similarity([movie_embedding], embeddings_df['embedding'].tolist())
    similar_movies = embeddings_df.iloc[np.argsort(similarities[0])[::-1][:top_n]]
    return similar_movies

# Example: Recommend movies similar to a given movieId
recommendations = recommend_movies('12345', embeddings_df)

3b. Developing the Recommender System ( Neural Collaborative Filtering)

import torch
import torch.nn as nn
import torch.optim as optim
from torch.utils.data import DataLoader, Dataset

class NCF(nn.Module):
    def __init__(self, num_users, num_items, embedding_dim):
        super(NCF, self).__init__()
        self.user_embedding = nn.Embedding(num_users, embedding_dim)
        self.item_embedding = nn.Embedding(num_items, embedding_dim)
        self.fc1 = nn.Linear(embedding_dim * 2, 128)
        self.fc2 = nn.Linear(128, 64)
        self.fc3 = nn.Linear(64, 1)
        self.sigmoid = nn.Sigmoid()

    def forward(self, user, item):
        user_embedded = self.user_embedding(user)
        item_embedded = self.item_embedding(item)
        x = torch.cat([user_embedded, item_embedded], dim=-1)
        x = torch.relu(self.fc1(x))
        x = torch.relu(self.fc2(x))
        x = self.sigmoid(self.fc3(x))
        return x

# Dummy dataset for illustration
class MovieLensDataset(Dataset):
    def __init__(self, user_ids, item_ids, ratings):
        self.user_ids = user_ids
        self.item_ids = item_ids
        self.ratings = ratings

    def __len__(self):
        return len(self.user_ids)

    def __getitem__(self, idx):
        return self.user_ids[idx], self.item_ids[idx], self.ratings[idx]

# Example data
num_users = 1000
num_items = 1700
user_ids = torch.randint(0, num_users, (10000,))
item_ids = torch.randint(0, num_items, (10000,))
ratings = torch.randint(0, 2, (10000,)).float()

dataset = MovieLensDataset(user_ids, item_ids, ratings)
dataloader = DataLoader(dataset, batch_size=64, shuffle=True)

# Instantiate model, loss function, and optimizer
embedding_dim = 50
model = NCF(num_users, num_items, embedding_dim)
criterion = nn.BCELoss()
optimizer = optim.Adam(model.parameters(), lr=0.001)

# Training loop
for epoch in range(5):
    for user, item, rating in dataloader:
        outputs = model(user, item)
        loss = criterion(outputs.squeeze(), rating)

    print(f'Epoch {epoch+1}, Loss: {loss.item()}')

For another advanced approach, refer to 🔸 A-TE-1: GNN-Based Recommender Systems.

4. Model Evaluation and Refinement

# Evaluation metrics
from sklearn.metrics import precision_score, recall_score, f1_score

# Example: Calculate Precision, Recall, and F1-Score
y_true = [1, 0, 1, 1, 0]  # Example ground truth labels
y_pred = [1, 0, 1, 0, 0]  # Example predicted labels

precision = precision_score(y_true, y_pred)
recall = recall_score(y_true, y_pred)
f1 = f1_score(y_true, y_pred)

print(f"Precision: {precision}, Recall: {recall}, F1-Score: {f1}")

Evaluation Process

For a comprehensive understanding of the evaluation process and STEM-Away tacks, please take a moment to review the general details provided here. Familiarizing yourself with this information will ensure a smoother experience throughout the assessment.

For the first part of the evaluation (MCQ), please click on the evaluation button located at the end of the post. Applicants achieving a passing score of 8 out of 10 will be invited to the second round of evaluation.

Advancing to the Second Round:
If you possess the required expertise for an advanced conversation with the AI Evaluator, you may opt to bypass the virtual internships and directly pursue skill certifications.

Evaluation for our Virtual-Internships Admissions
  • Start with a Brief Project Overview: Begin by summarizing the project objectives and the key technologies you used (Recommender Systems, Embeddings, OpenAI API, Machine Learning Models). This sets the context for the discussion.

  • Discuss Model Construction: Explain the process of building the recommender system models. Discuss any challenges you faced, such as selecting the right model architecture, handling data sparsity, or optimizing model performance, and how you addressed these issues.

  • Challenges and Problem-Solving: Present a specific challenge you faced, like improving the model’s accuracy or handling scalability issues. Explain your solution and how it impacted the recommendation quality and insights. This shows critical thinking and problem-solving skills.

  • Insights from Model Development: Share an interesting finding from your model development process. For example, “I found that using collaborative filtering combined with content-based methods improved the recommendation accuracy significantly compared to using either method alone.”

  • Real-world Application: Discuss how you would apply this recommender system in real-world scenarios. Talk about potential applications in personalized content recommendations, e-commerce, streaming services, or social media platforms, and the implications of your findings.

  • Learning and Growth: End by reflecting on your learning journey such as “Working on this project, I gained a deep understanding of how different recommender system models can be tailored to specific use cases. I also learned the importance of evaluating model performance using various metrics to ensure robust recommendations.”

  • Ask Questions: Show curiosity by asking the AI mentor questions. For example, “I’m curious, how do large-scale recommender systems handle real-time updates to user preferences and item availability? What are some best practices for maintaining high performance in dynamic environments?”

Evaluations for Skill Certifications for our Talent Discovery Platform
  • Model Construction and Completeness:

    • Model Accuracy: Discuss the accuracy and completeness of the recommender system models you constructed. Provide examples of how well the models handled the dataset and any areas where they could be improved.
    • Challenges Faced: Describe any significant challenges encountered during the model construction and how you addressed these issues. For example, handling cold-start problems, ensuring scalability, or optimizing the performance of the recommender models.
  • Model Techniques:

    • Model Methods: Explain the different model methods you used, such as collaborative filtering, content-based filtering, or hybrid models. Highlight significant findings or challenges you encountered, such as which models provided the best performance for your recommender system.
    • Learning Curves: Discuss the trends observed during the model development process, highlighting any substantial discoveries or persistent challenges, such as improving recommendation accuracy or handling diverse data sources.
  • Scalability and Practical Applications:

    • Handling Complex Datasets: Describe any challenges you faced with the dataset’s complexity and size. Discuss strategies you employed for managing large-scale data, ensuring scalability, and optimizing your recommender system models for real-time performance.
    • Application of Findings: Share how the insights gained from the model development could be applied in real-world scenarios, particularly in the domain of recommender systems. Discuss potential applications in personalized content recommendations, e-commerce, streaming services, or social media platforms.
  • Comparative Analysis and Methodology Evaluation:

    • Methodology Comparison: Compare the methodologies used in constructing and analyzing the recommender system models, such as different filtering techniques or machine learning models. Highlight how certain methodologies were more effective in revealing meaningful recommendations and capturing user preferences.
    • Tool Effectiveness: Evaluate the effectiveness of the tools and libraries used, such as OpenAI Embedding API, collaborative filtering algorithms, or deep learning frameworks. Discuss the advantages and limitations of each tool in the context of your project.
  • Domain-Specific Considerations:

    • Recommender Systems: Discuss the importance of recommender systems in various applications like content curation, e-commerce, or personalized advertising. Highlight how your analysis can contribute to enhancing user experiences by providing more relevant and contextually accurate recommendations.
    • Related Fields and Tools: Mention other relevant fields such as user behavior analysis, personalization algorithms, or natural language understanding, and how similar techniques can be applied. Discuss the use of additional tools like TensorFlow, PyTorch, or scikit-learn for expanding the model’s capabilities and improving recommendation accuracy.
  • Advanced Techniques and Tools: Share any advanced techniques or tools you explored, such as using hybrid models for combining collaborative and content-based filtering, incorporating reinforcement learning for dynamic recommendations, or leveraging graph-based methods for capturing complex user-item interactions.


Environment Setup

Environment Setup

Before you can begin working on the project, you’ll need to set up your programming environment. If you’re new to Python or need a refresher, here’s a step-by-step guide to get you started:

1. Install Python

Download and install Python from the official Python website: Download Python | Python.org. The latest version as of my training cut-off in September 2021 is Python 3.9, but any version from Python 3.6 and up should work for this project.

2. Install pip

pip is a package manager for Python that we’ll use to install the necessary libraries for this project. If you installed Python from the official website, you should already have pip installed. You can check by typing pip --version in your command line.

If you don’t have pip installed, you can follow the instructions here: Installation - pip documentation v24.1

3. Set up a Virtual Environment

It’s a good practice to create a virtual environment for each of your Python projects. This isolates your project and its dependencies from other projects, which can prevent version conflicts.

Here’s how you can set up a virtual environment:

  • On Windows:
python -m venv myenv
  • On macOS and Linux:
python3 -m venv myenv

Replace myenv with the name you want to give your virtual environment.

To activate the virtual environment, navigate to the directory where you created the environment and run:

  • On Windows:
  • On macOS and Linux:
source myenv/bin/activate

4. Install Necessary Libraries

Once your virtual environment is activated, you can install the necessary Python libraries for this project using pip. For this project, you’ll likely need the following libraries:

  • numpy
  • pandas
  • sklearn
  • nltk
  • tensorflow or pytorch (for BERT embeddings)
  • gensim (for word2vec and GloVe embeddings)

You can install them using the following command:

pip install numpy pandas scikit-learn nltk tensorflow gensim

For PyTorch installation, follow the guide on the official PyTorch website (https://pytorch.org/), as the installation command varies depending on your system and whether you have CUDA available.

With these steps, you should have your programming environment set up and ready to go for this project. Happy coding!

OpenAI Setup

1. Create an OpenAI Account

Go to https://beta.openai.com/signup/ and sign up for an account. You will need to provide some information, including your email address. After you sign up, you should receive a confirmation email. Once your email is confirmed, you can log in to your account.

2. Get Your API Key

Once you’ve logged into your OpenAI account, navigate to the API section of the dashboard (https://beta.openai.com/dashboard/api-keys/). From here, you can generate a new API key.

3. Install OpenAI Python Client

You can install the OpenAI Python client library using pip:

pip install openai

4. Use the API Key in Your Code

Now that you have your API key, you can use it in your Python code to make requests to the OpenAI API. Here’s an example of how you might use it:

import openai

openai.api_key = 'your-api-key'

# Example usage of the API:
response = openai.TextEmbeddings.create(
  texts=["Once upon a time..."]

Replace 'your-api-key' with the API key you obtained from the OpenAI dashboard. Be sure to keep your API key confidential, do not publish or share it with anyone, and do not commit it in version control systems.

That’s it! You should now be able to use OpenAI’s Embedding API in your project. Remember to follow OpenAI’s usage policies and guidelines while using their APIs.

Access the Code-Along for this Skill-Builder Project to join discussions, utilize the t3 AI Mentor, and more.