16th Athens Big Data Meetup - 1st Talk - An Introduction to Machine Learning with Python and Scikit-Learn
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Title: An Introduction to Machine Learning with Python and Scikit-Learn Speaker: Julien Simon (https://linkedin.com/in/juliensimon/) Date: Thursday, March 14, 2019 Event: https://www.meetup.com/Athens-Big-Data/events/259091496/
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16th Athens Big Data Meetup - 1st Talk - An Introduction to Machine Learning with Python and Scikit-Learn
- 1. An Introduction to Machine Learning with Python and scikit-learn Julien Simon Global Evangelist, AI and Machine Learning, AWS @julsimon
- 2. © 2018, Amazon Web Services, Inc. or Its Affiliates. All rights reserved. Agenda • Machine Learning in 5 minutes • Scikit-learn • Algos & Demos: Linear Regression, Logistic Regression, Decision Trees, K-Means, Principal Component Analysis • Scikit-learn on Amazon SageMaker • Resources
- 3. Machine Learning in 5 minutes
- 4. Artificial Intelligence: design software applications which exhibit human-like behavior, e.g. speech, natural language processing, reasoning or intuition Machine Learning: using statistical algorithms, teach machines to learn from featurized data without being explicitly programmed Deep Learning: using neural networks, teach machines to learn from complex data where features cannot be explicitly expressed
- 5. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Supervised learning • Run an algorithm on a labeled data set. • The model learns how to correctly predict the right answer. • Regression and classification are examples of supervised learning. Unsupervised learning • Run an algorithm on an unlabeled data set. • The model learns patterns and organizes samples accordingly. • Clustering and topic modeling are examples of unsupervised learning. Types of Machine Learning
- 6. © 2018, Amazon Web Services, Inc. or Its Affiliates. All rights reserved. Data Visualization & Analysis Business Problem ML problem framing Data Collection Data Integration Data Preparation & Cleaning Feature Engineering Model Training & Parameter Tuning Model Evaluation Are Business Goals met? Model Deployment Monitoring & Debugging YesNo DataAugmentation Feature Augmentation The Machine Learning Process Re-training Predictions
- 7. Scikit-learn
- 8. © 2018, Amazon Web Services, Inc. or Its Affiliates. All rights reserved. Scikit-learn • Open Source library in Python released in February 2010 • Built on NumPy, SciPy, and matplotlib • Simple tools for data analysis and Machine Learning • Excellent collection of algorithms • Very good documentation, tons of tutorials • Limited scalability for data sets that don’t fit in RAM • Not appropriate for Deep Learning (no GPU support)
- 9. © 2018, Amazon Web Services, Inc. or Its Affiliates. All rights reserved. http://scikit-learn.org/stable/tutorial/machine_learning_map/
- 10. © 2018, Amazon Web Services, Inc. or Its Affiliates. All rights reserved. Linear Regression https://en.wikipedia.org/wiki/Linear_regression • Supervised learning algorithm • Goal: fit data to a linear function in order to predict numerical values • Data set: features + target (scalar or scalar vector) • 1 feature à line, 2 features à plane, etc. • Intuition: minimize the “distance” between data points and the linear function This can also be used for binary classification: a sample is either “above” or “below” the linear function
- 11. © 2018, Amazon Web Services, Inc. or Its Affiliates. All rights reserved. Logistic Regression (1958) https://en.wikipedia.org/wiki/Logistic_regression • Supervised learning algorithm • Goal: fit data to a linear function in order to predict the class of a sample • Data set : features + binary label (yes/no, true/false, etc.) • This algorithm can be extended to more than two classes • Intuition: find a function computing a score between 0 and 1 and set a threshold separating both classes
- 12. © 2018, Amazon Web Services, Inc. or Its Affiliates. All rights reserved. Decision Trees https://en.wikipedia.org/wiki/Decision_tree • Supervised learning algorithm • Goal: build a decision tree for regression or classification • Data set : features + target value / class • Intuition: find the “best” feature thresholds to go left or right • “Easy” to interpret, but prone to overfitting • Plenty of advanced variants with multiple trees: Random Forests, XGBoost (2016), etc.
- 13. © 2018, Amazon Web Services, Inc. or Its Affiliates. All rights reserved. K-means (1957) https://en.wikipedia.org/wiki/K-means_clustering • Unsupervised learning algorithm • Goal: group samples in ‘k’ clusters • Data set : features only • Intuition: find ‘k’ cluster centers that minimize the “distance” to their respective samples • This assumes “spherical” clusters of similar ”radius”: maybe, maybe not!
- 14. © 2018, Amazon Web Services, Inc. or Its Affiliates. All rights reserved. Principal Component Analysis aka PCA (1901!) https://en.wikipedia.org/wiki/Principal_component_analysis • Unsupervised learning algorithm • Goal: build a new data set with a smaller number of uncorrelated features (aka Dimensionality Reduction) …keeping as much variance as the number of new features will allow • Data set : features only • Sample use cases: • Visualize high-dimension data sets in 2D or 3D • Remove correlation in high-dimension datasets • Preliminary step to building linear models
- 15. Demos - Linear Regression - Logistic Regression - Decision Trees - K-Means - PCA - PCA + Logistic Regression on MNIST https://gitlab.com/juliensimon/aws --> ML/scikit
- 16. © 2018, Amazon Web Services, Inc. or Its Affiliates. All rights reserved. Scaling scikit-learn • Scikit-learn runs on a single machine, loading the full data set in memory • Scaling options are quite limited http://scikit-learn.org/stable/modules/computing.html • Some algorithms can leverage multi-core (joblib) • Some algorithms support incremental training • Amazon SageMaker can help • Use ML-optimized multi-core instances (C5) • Use pipe mode, i.e. the ability to stream data from Amazon S3
- 17. © 2018, Amazon Web Services, Inc. or Its Affiliates. All rights reserved. Beyond scikit-learn • Amazon SageMaker • Train models on fully-managed infrastructure at any scale • Built-in algorithms (17) for regression, classification, etc. • Built-in environments for scikit-learn and Deep Learning librairies • Apache Spark MLLib • Available in Amazon Elastic Map Reduce (EMR) • Distributed processing by design • Nice collection of Machine Learning algorithms • Seamless integration with Amazon SageMaker (Scala / PySpark SDK)
- 19. Thank you! Julien Simon Global Evangelist, AI and Machine Learning, AWS @julsimon