ML with Python : Zero to Hero | Video 11 | Sentiment Analysis | Venkat Reddy AI Classes

Introduction

Introduction to Sentiment Analysis

Until now, we have discussed data preparation, including converting non-numerical data into numerical data, which is essential because text data cannot be analyzed directly. Moving forward, we will delve into sentiment analysis, which is one of the most widely used applications in text data.

What is Sentiment Analysis?

Sentiment analysis, also known as opinion mining or sentiment mining, involves analyzing text data to determine whether a given review is positive or negative. Since text data cannot be directly used for analysis, it is converted into a numerical form known as a document-term matrix (DTM). Once the text data is in DTM form, sentiment analysis can be applied.

Document-Term Matrix (DTM)

Before diving into sentiment analysis, we need to convert the text data into a document-term matrix. This matrix represents the frequency of terms that appear in a collection of documents.

Sentiment Analysis Algorithm

For sentiment analysis, we generally don't use traditional machine learning algorithms like logistic regression or decision tree due to the sparse nature of document-term matrices. Instead, we use a probability-based algorithm called the Naive Bayes model, which works effectively even on sparse data.

Understanding Naive Bayes

The Naive Bayes model is derived from Bayes' theorem: [ P(A|B) = \frac(P(B|A) \cdot P(A))(P(B)) ]

Although Bayes' theorem might seem complex, it becomes straightforward once understood. Here's a simplified example to illustrate:

Example: Factory Producing Nuts and Bolts

Imagine a factory with two machines, A1 and A2, producing nuts and bolts. Machine A1 produces 60% of the items with a 1% defect rate, while Machine A2 produces 40% with a 5% defect rate. Using Bayes' theorem, we can calculate the probability of a defect given either machine produced it.

By calculating these probabilities, we can use the Naive Bayes model to determine whether a given review is more likely to be positive or negative based on its terms.

Applying Sentiment Analysis

After pre-processing the data and converting it into a DTM, we use the Naive Bayes algorithm for sentiment analysis. This involves training the model on labeled data (positive or negative sentiments) and then using the model to predict sentiments on new, unseen data.

Practical Example

Consider a dataset of Twitter sentiments. We start by removing neutral sentiments, converting text data to a DTM, and then training the Naive Bayes model. Once trained, the model can predict sentiments of new tweets.

New Data Prediction

For a new tweet "Awesome experience, go for it; it's a great place," the steps are:

1. Convert the tweet into DTM format.
2. Use the trained Naive Bayes model to predict the sentiment.

Industry Applications

Sentiment analysis is applicable across various industries, including e-commerce, healthcare, hospitality, and more. It’s a valuable skill to have on your resume, regardless of your background.

Conclusion

Understanding sentiment analysis and mastering text data pre-processing can significantly enhance your data science skills. It's recommended to practice sentiment analysis on different datasets and include this project in your resume to showcase your expertise.

Keywords

• Sentiment Analysis
• Opinion Mining
• Text Data
• Numerical Data
• Document-Term Matrix (DTM)
• Machine Learning
• Naive Bayes Model
• Bayes' Theorem
• Data Pre-processing
• Twitter Sentiments

FAQs

1. What is sentiment analysis? Sentiment analysis involves determining whether a given text, such as a review or tweet, has a positive or negative sentiment.

2. Why can't we directly analyze text data? Text data needs to be converted into a numerical form, such as a document-term matrix, because machine learning algorithms require numerical input.

3. What is a document-term matrix (DTM)? A DTM is a matrix that represents the frequency of terms that appear in a collection of documents.

4. What machine learning algorithm is used in sentiment analysis? The Naive Bayes model is commonly used because it effectively handles sparse data typical in document-term matrices.

5. How does Naive Bayes work? Naive Bayes applies Bayes' theorem to calculate the probability of a sentiment (positive or negative) given the terms in a text.

6. Where is sentiment analysis used? Sentiment analysis can be applied in various industries, including e-commerce, healthcare, hospitality, and more, to analyze customer reviews and feedback.

7. What should be done with neutral sentiments in the dataset? Neutral sentiments can be either ignored or reclassified as positive or negative, depending on the context and requirements of the analysis.

8. Can sentiment analysis handle new words in the data? The pre-processing code should identify and remove any new words not present in the training data to ensure consistent model performance.