Table of Contents
- 1.1 What is Machine Learning
Notation
- Capital Letters: Random variables, matrices, number of classes (clear by context)
- Bold: Vectors (column vectors, unless transposed)
- Hats: estimates
Vocab
- i.i.d: Independently and identically distributed
- Joint Distribution: Probablility of something occuring taking into account 2 or more random variables
- Supervised Learning: Learning with a training set
- Unsupervised Learning: Learning with a set of data without values
- Feature Vectors: These are the vectors that “describe” a defining feature of the data
- Feature Space: Vector space containing the feature vectors
- Finite Set: Labels occur from {-1, 1}
- Non-Finite Set: Labels occur on real number line
- Classification (Pattern Recognition): Supervised learning with a finite set of labels
- Labels are called classes
- Clustering: Data grouped together giving away some sort of pattern
1.1 What is Machine Learning
- Supervised Learning: Machine Learning with a training set T. Feature vectors x generate labels y
- Data is drawn i.i.d from some joint distribution
- Vectors x_i are feature vectors or inputs
- Values y_i are known as labels (outputs, responses)
- Feature Space: Vector space containing the feature vectors
- The goal of supervised learning is to create a map from the training data
- This allows us to create a model to predict output values
- This process is called learning or training a model
- Classification (Pattern Recognition)
- Labels are a finite-set {-1, 1}
- Labels are now known as classses
- Then the supervised problem is known as classification or pattenr recognition
- Labels are a non-finite set, any real number
- Then the supervised problem is known as regression
- Labels are a finite-set {-1, 1}
- Unsupervised Learning: Machine Learning without a training set but only a set of data (feature vectors)
- Data is drawn i.i.d and we want to infer something useful from the data
- Clustering is used to identify such patterns
- Take vectors from D and group them into similar groups