Statistical Learning
Clustering in Partially Labeled Stochastic Block Models via Total Variation Minimization
A main task in data analysis is to organize data points into coherent groups or clusters. The stochastic block model is a probabilistic model for the cluster structure. This model prescribes different probabilities for the presence of edges within a cluster and between different clusters. We assume that the cluster assignments are known for at least one data point in each cluster. In such a partially labeled stochastic block model, clustering amounts to estimating the cluster assignments of the remaining data points. We study total variation minimization as a method for this clustering task. We implement the resulting clustering algorithm as a highly scalable message passing protocol. We also provide a condition on the model parameters such that total variation minimization allows for accurate clustering.
Attributed Sequence Embedding
Zhuang, Zhongfang, Kong, Xiangnan, Rundensteiner, Elke, Zouaoui, Jihane, Arora, Aditya
Mining tasks over sequential data, such as clickstreams and gene sequences, require a careful design of embeddings usable by learning algorithms. Recent research in feature learning has been extended to sequential data, where each instance consists of a sequence of heterogeneous items with a variable length. However, many real-world applications often involve attributed sequences, where each instance is composed of both a sequence of categorical items and a set of attributes. In this paper, we study this new problem of attributed sequence embedding, where the goal is to learn the representations of attributed sequences in an unsupervised fashion. This problem is core to many important data mining tasks ranging from user behavior analysis to the clustering of gene sequences. This problem is challenging due to the dependencies between sequences and their associated attributes. We propose a deep multimodal learning framework, called NAS, to produce embeddings of attributed sequences. The embeddings are task independent and can be used on various mining tasks of attributed sequences. We demonstrate the effectiveness of our embeddings of attributed sequences in various unsupervised learning tasks on real-world datasets.
Generalized Learning with Rejection for Classification and Regression Problems
Asif, Amina, Minhas, Fayyaz ul Amir Afsar
Learning with rejection (LWR) allows development of machine learning systems with the ability to discard low confidence decisions generated by a prediction model. That is, just like human experts, LWR allows machine models to abstain from generating a prediction when reliability of the prediction is expected to be low. Several frameworks for this learning with rejection have been proposed in the literature. However, most of them work for classification problems only and regression with rejection has not been studied in much detail. In this work, we present a neural framework for LWR based on a generalized meta-loss function that involves simultaneous training of two neural network models: a predictor model for generating predictions and a rejecter model for deciding whether the prediction should be accepted or rejected. The proposed framework can be used for classification as well as regression and other related machine learning tasks. We have demonstrated the applicability and effectiveness of the method on synthetically generated data as well as benchmark datasets from UCI machine learning repository for both classification and regression problems. Despite being simpler in implementation, the proposed scheme for learning with rejection has shown to perform at par or better than previously proposed methods. Furthermore, we have applied the method to the problem of hurricane intensity prediction from satellite imagery. Significant improvement in performance as compared to conventional supervised methods shows the effectiveness of the proposed scheme in real-world regression problems.
Towards calibrated and scalable uncertainty representations for neural networks
Seedat, Nabeel, Kanan, Christopher
For many applications it is critical to know the uncertainty of a neural network's predictions. While a variety of neural network parameter estimation methods have been proposed for uncertainty estimation, they have not been rigorously compared across uncertainty measures. We assess four of these parameter estimation methods to calibrate uncertainty estimation using four different uncertainty measures: entropy, mutual information, aleatoric uncertainty and epistemic uncertainty. We also evaluate their calibration using expected calibration error. We additionally propose a novel method of neural network parameter estimation called RECAST, which combines cosine annealing with warm restarts with Stochastic Gradient Langevin Dynamics, capturing more diverse parameter distributions. When benchmarked against mutilated data from MNIST, we show that RECAST is well-calibrated and when combined with predictive entropy and epistemic uncertainty it offers the best calibrated measure of uncertainty when compared to recent methods.
Maximum Entropy Diverse Exploration: Disentangling Maximum Entropy Reinforcement Learning
Cohen, Andrew, Yu, Lei, Qiao, Xingye, Tong, Xiangrong
Two hitherto disconnected threads of research, diverse exploration (DE) and maximum entropy RL have addressed a wide range of problems facing reinforcement learning algorithms via ostensibly distinct mechanisms. In this work, we identify a connection between these two approaches. First, a discriminator-based diversity objective is put forward and connected to commonly used divergence measures. We then extend this objective to the maximum entropy framework and propose an algorithm Maximum Entropy Diverse Exploration (MEDE) which provides a principled method to learn diverse behaviors. A theoretical investigation shows that the set of policies learned by MEDE capture the same modalities as the optimal maximum entropy policy. In effect, the proposed algorithm disentangles the maximum entropy policy into its diverse, constituent policies. Experiments show that MEDE is superior to the state of the art in learning high performing and diverse policies.
Measuring Similarity of Interactive Driving Behaviors Using Matrix Profile
Lin, Qin, Wang, Wenshuo, Zhang, Yihuan, Dolan, John
-- Understanding multi-vehicle interactive behaviors with temporal sequential observations is crucial for autonomous vehicles to make appropriate decisions in an uncertain traffic environment. On-demand similarity measures are significant for autonomous vehicles to deal with massive interactive driving behaviors by clustering and classifying diverse scenarios. This paper proposes a general approach for measuring spatiotemporal similarity of interactive behaviors using a multivariate matrix profile technique. The key attractive features of the approach are its superior space and time complexity, real-time online computing for streaming traffic data, and possible capability of leveraging hardware for parallel computation. The proposed approach is validated through automatically discovering similar interactive driving behaviors at intersections from sequential data. One of the biggest challenges for deploying autonomous vehicles (A Vs) in real life is the requirement of the A Vs' capability to interact with surrounding road users. Classifying diverse scenarios and separately designing appropriate decisions using on-hand prior knowledge is unfortunately not realistic [1] because of the diversity of scenarios that are far larger and messier than human beings can cope with [2].
On EducationMachine Learning Basics: Classification models in Python - CouponED
WHAT YOU WILL LEARN Understand how to interpret the result of Logistic Regression model and translate them into actionable insight Learn how to solve real life problem using the different classification techniques Predict future outcomes basis past data by implementing Machine Learning algorithm Course contains a end-to-end DIY project to implement your learnings from the lectures The course "Machine Learning Basics: Classification models in Python" teaches you all the steps of creating a Classification model to solve business problems. Below is a list of popular FAQs of students who want to start their Machine learning journey- What is Machine Learning? Machine Learning is a field of computer science which gives the computer the ability to learn without being explicitly programmed. It is a branch of artificial intelligence based on the idea that systems can learn from data, identify patterns and make decisions with minimal human intervention. Which all classification techniques are taught in this course?
XGBoost in Amazon SageMaker
SageMaker is Amazon Web Services' (AWS) machine learning platform that works in the cloud. It is fully-managed and allows one to perform an entire data science workflow on the platform. And in this post, I will show you how to call your data from AWS S3, upload your data into S3 and bypassing local storage, train a model, deploy an endpoint, perform predictions, and perform hyperparameter tuning. The data cleaning and feature engineering code are derived from this blog post, which is written by Andrew Long, who gave full permission to use his code. The dataset can be found here. Head over to your AWS dashboard and find SageMaker, and on the left sidebar, click on Notebook instances .
Case study: explaining credit modeling predictions with SHAP
At Fiddler labs, we are all about explaining machine learning models. One recent interesting explanation technology is SHAP (SHapely Additive exPlanations). To learn more about how SHAP works in practice, we applied it to predicting loan defaults in data from Lending Club. We built three models (random, logistic regression, and boosted trees), and looked at several feature explanation diagrams from each. We are not financial experts, so this blog post focuses on comparing algorithms, not insights into loan data. Hopefully, we can bring SHAP into sharper focus.
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