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Mihir Thakkar Founder and Instructor hello@codeheroku.com Introduction to Unsupervised Machine Learning
SESSION OBJECTIVES ● Quick Recap ● Unsupervised Learning ● Implement a Clustering Algorithm in Python
Types of Machine Learning Algorithms Supervised Machine Learning House Size (Sq feet) Location Age (years) Prize (Lakh Rs) 500 Mumbai 2 70 1500 Pune 3 100 2000 Banglore 4 60 1000 Mumbai 2 ? 3000 Pune 10 ? Training Data Test Data
www.codeheroku.com Introduction to Unsupervised Machine Learning Brain scans by functional magnetic resonance imaging. An illustration of finding interesting underlying phenomena in high-dimensional data (Beckmann et al, Phil. Trans. Royal Soc. B, 2005).
Types of Machine Learning Algorithms Unsupervised Machine Learning Unsupervised Machine Learning Algorithm
Supervised ML ● Labelled Dataset Unsupervised ML ● Prediction/Classification ● More formal problem ● Labels / targets are unknown ● Finding hidden patterns in unlabelled data ● Problem itself is ambiguous
www.codeheroku.com Introduction to Unsupervised Machine Learning Applications Of Unsupervised ML
Dimensionality Reduction
Image Compression
Anomaly Detection
Topic Mapping
QUIZ In which of these scenarios you would most likely use an unsupervised machine learning algorithm? 1. Given a set of images you are interested in grouping the ones which are similar 2. Given training data about a user’s preferences you are interested in knowing whether they would like/dislike a movie 3. Given a set of 1000 features you are interested in finding features that capture maximum variance in the data
www.codeheroku.com Introduction to Unsupervised Machine Learning Clustering Movie Time IMDB Rating
www.codeheroku.com Introduction to Unsupervised Machine Learning Clustering Movie Time IMDB Rating 1. Proximity Measures 1. Evaluation Criteria => What a good cluster looks like?
www.codeheroku.com Introduction to Unsupervised Machine Learning K-means
Initialize K centroids randomly
Step 1: Assignment Assign each data point a cluster based on closest centroid
Step 2: Move Centroid Move centroid to location which is the mean of all points in that cluster
Move centroid to location which is the mean of all points in that cluster
Assign
Move centroid
Assign
Quiz The distortion of a cluster is given by the formula below. Calculate the distortion of a clustering algorithm with following values Data X Data Y Centroid X Centroid Y 5 2 3 3 3 3 2 2 Ans: (5-3)2 + (2-3)2 + 0 + (2-3)2 + (2-3)2Ans: (5-3)2 + (2-3)2 + 0 + (2-3)2 + (2-3)2
www.codeheroku.com Introduction to Unsupervised Machine Learning Optimal Number of K
www.codeheroku.com Introduction to Unsupervised Machine Learning Will we always get the best solution?
www.codeheroku.com Introduction to Unsupervised Machine Learning Seen this before?
www.codeheroku.com Introduction to Unsupervised Machine Learning Outliers!!
www.codeheroku.com Introduction to Unsupervised Machine Learning Let’s Build It https://drive.google.com/file/d/1wLwOro1YhfpPr0YqYywx6zLcLn8Ceh30/view?usp=sharing https://github.com/codeheroku/Introduction-to-Machine-Learning/tree/master/
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