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Describes about Machine Learning
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WHAT IS MACHINE
LEARNING
Bhaskara Reddy Sannapureddy, Senior Project Manager @Infosys, +91-7702577769
WHAT IS MACHINE
LEARNING?
Automating automation
Getting computers to program themselves
Writing software is the bottleneck
Let the data do the work instead!
ComputerData
ProgramOutput
Computer
Data
OutputProgram
T R A D I T I O N A L P R O G R A M M I N G V S
M A C H I N E L E A R N I N G
Traditional Programming
Machine Learning
MAGIC?
No, more like gardening
Seeds = Algorithms
Nutrients = Data
Gardener = You
Plants = Programs
SAMPLE APPLICATIONS
Web search Computational biologyFinanceE-commerceSpace explorationRoboticsInformation extractionSocial networksDebugging[Your favorite area]
ML IN A NUTSHELL
Tens of thousands of machine learning algorithms
Hundreds new every year
Every machine learning algorithm has three components:
• Representation
• Evaluation
• Optimization
REPRESENTATION
Decision trees
Sets of rules / Logic programs
Instances
Graphical models (Bayes/Markov nets)
Neural networks
Support vector machines
Model ensembles
Etc.
EVALUATION
AccuracyPrecision and recallSquared errorLikelihoodPosterior probabilityCost / UtilityMarginEntropyK-L divergenceEtc.
OPTIMIZATION
Combinatorial optimization
• E.g.: Greedy search
Convex optimization
• E.g.: Gradient descent
Constrained optimization
• E.g.: Linear programming
TYPES OF LEARNING
Supervised (inductive) learning
• Training data includes desired outputs
Unsupervised learning
• Training data does not include desired outputs
Semi-supervised learning
• Training data includes a few desired outputs
Reinforcement learning
• Rewards from sequence of actions
INDUCTIVE LEARNING
Given examples of a function (X, F(X))
Predict function F(X) for new examples X
• Discrete F(X): Classification
• Continuous F(X): Regression
• F(X) = Probability(X): Probability estimation
Supervised learning
• Decision tree induction
• Rule induction
• Instance-based learning
• Bayesian learning
• Neural networks
• Support vector machines
• Model ensembles
• Learning theory
Unsupervised learning
• Clustering
• Dimensionality reduction
SUPERVISED AND
UNSUPERVISED LEARNING
MACHINE LEARNING
PROBLEMS
ML IN PRACTICE
Understanding domain, prior knowledge, and goals
Data integration, selection, cleaning,
pre-processing, etc.
Learning models
Interpreting results
Consolidating and deploying discovered knowledge
Loop
CLUSTERING STRATEGIES
K-means
• Iteratively re-assign points to the nearest cluster center
Agglomerative clustering
• Start with each point as its own cluster and iteratively merge the closest clusters
Mean-shift clustering
• Estimate modes of pdf
Spectral clustering
• Split the nodes in a graph based on assigned links with similarity weights
As we go down this chart, the clustering strategies have
more tendency to transitively group points even if they are
not nearby in feature space
THE MACHINE LEARNING
FRAMEWORK
Apply a prediction function to a feature representation of the
image to get the desired output:
Slide credit: L. Lazebnik
THE MACHINE LEARNING
FRAMEWORK
y = f(x)
Training: given a training set of labeled examples {(x1,y1), …, (xN,yN)}, estimate the
prediction function f by minimizing the prediction error on the training set
Testing: apply f to a never before seen test example x and output the predicted value y = f(x)
output prediction
function
Image
feature
Slide credit: L. Lazebnik
THANK YOU