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Note: This course is a subset of our 20+ hour course 'From 0 to 1: Machine Learning & Natural Language Processing' so please don't sign up for both:-)
Sentiment Analysis (or) Opinion Mining is a field of NLP that deals with extracting subjective information (positive/negative, like/dislike, emotions).
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|Section 1: What Are You Feeling Like?|
You, This Course, and Us!Preview
|Lots of new stuff coming up in the next few classes. Sentiment Analysis (or) Opinion Mining is a field of NLP that deals with extracting subjective information (positive/negative, like/dislike, emotions). Learn why it's useful and how to approach the problem. There are Rule-Based and ML-Based approaches. The details are really important - training data and feature extraction are critical. Sentiment Lexicons provide us with lists of words in different sentiment categories that we can use for building our feature set. All this is in the run up to a serious project to perform Twitter Sentiment Analysis. We'll spend some time on Regular Expressions which are pretty handy to know as we'll see in our code-along.|
As people spend more and more time on the internet, and the influence of social media explodes, knowing what your customers are saying about you online, becomes crucial. Sentiment Analysis comes in handy here - This is an NLP problem that can be approached in multiple ways. We examine a couple of rule based approaches, one of which has become standard fare (VADER)
SVM and Naive Bayes are popular ML approaches to Sentiment Analysis. But the devil really is in the details. What do you use for training data? What features should you use? Getting these right is critical.
|Sentiment Lexicon's are a great help in solving problems where the subjectivity/emotion expressed by a word are important. SentiWordNet is different even among the popular sentiment lexicons (General Inquirer, LIWC, MPQA etc) all of which are touched upon|
Anaconda's iPython is a Python IDE. The best part about it is the ease with which one can install packages in iPython - 1 line is virtually always enough. Just say '!pip'
|Numpy arrays are pretty cool for performing mathematical computations on your data.|
|We continue with a basic tutorial on Numpy and Scipy|
Regular expressions are a handy tool to have when you deal with text processing. They are a bit arcane, but pretty useful in the right situation. Understanding the operators from basics help you build up to constructing complex regexps.
re is the module in python to deal with regular expressions. It has functions to find a pattern, substitute a pattern etc within a string.
A serious project - Accept a search term from a user and output the prevailing sentiment on Twitter for that search term. We'll use the Twitter API, Sentiwordnet, SVM, NLTK, Regular Expressions - really work that coding muscle :)
|We'll accept a search term from a user and download a 100 tweets with that term. You'll need a corpus to train a classifier which can classifiy these tweets. The corpus has only tweet_ids, so connect to Twitter API and fetch the text for the tweets.|
The tweets that we downloaded have a lot of garbage, clean it up using regular expressions and NLTK and get a nice list of words to represent each tweet.
We'll train 2 different classifiers on our training data , Naive Bayes and SVM. The SVM will use Sentiwordnet to assign weights to the elements of the feature vector.
Loonycorn is us, Janani Ravi, Vitthal Srinivasan, Swetha Kolalapudi and Navdeep Singh. Between the four of us, we have studied at Stanford, IIM Ahmedabad, the IITs and have spent years (decades, actually) working in tech, in the Bay Area, New York, Singapore and Bangalore.
Janani: 7 years at Google (New York, Singapore); Studied at Stanford; also worked at Flipkart and Microsoft
Vitthal: Also Google (Singapore) and studied at Stanford; Flipkart, Credit Suisse and INSEAD too
Swetha: Early Flipkart employee, IIM Ahmedabad and IIT Madras alum
Navdeep: longtime Flipkart employee too, and IIT Guwahati alum
We think we might have hit upon a neat way of teaching complicated tech courses in a funny, practical, engaging way, which is why we are so excited to be here on Udemy!
We hope you will try our offerings, and think you'll like them :-)