课程信息
4.7
2,507 个评分
428 个审阅
专项课程

Course 3 of 4 in the

100% 在线

100% 在线

立即开始,按照自己的计划学习。
可灵活调整截止日期

可灵活调整截止日期

根据您的日程表重置截止日期。
完成时间(小时)

完成时间大约为24 小时

建议:7 weeks of study, 5-8 hours/week...
可选语言

英语(English)

字幕:英语(English), 阿拉伯语(Arabic)

您将获得的技能

Logistic RegressionStatistical ClassificationClassification AlgorithmsDecision Tree
专项课程

Course 3 of 4 in the

100% 在线

100% 在线

立即开始,按照自己的计划学习。
可灵活调整截止日期

可灵活调整截止日期

根据您的日程表重置截止日期。
完成时间(小时)

完成时间大约为24 小时

建议:7 weeks of study, 5-8 hours/week...
可选语言

英语(English)

字幕:英语(English), 阿拉伯语(Arabic)

教学大纲 - 您将从这门课程中学到什么

1
完成时间(小时)
完成时间为 1 小时

Welcome!

Classification is one of the most widely used techniques in machine learning, with a broad array of applications, including sentiment analysis, ad targeting, spam detection, risk assessment, medical diagnosis and image classification. The core goal of classification is to predict a category or class y from some inputs x. Through this course, you will become familiar with the fundamental models and algorithms used in classification, as well as a number of core machine learning concepts. Rather than covering all aspects of classification, you will focus on a few core techniques, which are widely used in the real-world to get state-of-the-art performance. By following our hands-on approach, you will implement your own algorithms on multiple real-world tasks, and deeply grasp the core techniques needed to be successful with these approaches in practice. This introduction to the course provides you with an overview of the topics we will cover and the background knowledge and resources we assume you have....
Reading
8 个视频 (总计 27 分钟), 3 个阅读材料
Video8 个视频
What is this course about?6分钟
Impact of classification1分钟
Course overview3分钟
Outline of first half of course5分钟
Outline of second half of course5分钟
Assumed background3分钟
Let's get started!分钟
Reading3 个阅读材料
Important Update regarding the Machine Learning Specialization10分钟
Slides presented in this module10分钟
Reading: Software tools you'll need10分钟
完成时间(小时)
完成时间为 2 小时

Linear Classifiers & Logistic Regression

Linear classifiers are amongst the most practical classification methods. For example, in our sentiment analysis case-study, a linear classifier associates a coefficient with the counts of each word in the sentence. In this module, you will become proficient in this type of representation. You will focus on a particularly useful type of linear classifier called logistic regression, which, in addition to allowing you to predict a class, provides a probability associated with the prediction. These probabilities are extremely useful, since they provide a degree of confidence in the predictions. In this module, you will also be able to construct features from categorical inputs, and to tackle classification problems with more than two class (multiclass problems). You will examine the results of these techniques on a real-world product sentiment analysis task....
Reading
18 个视频 (总计 78 分钟), 2 个阅读材料, 2 个测验
Video18 个视频
Intuition behind linear classifiers3分钟
Decision boundaries3分钟
Linear classifier model5分钟
Effect of coefficient values on decision boundary2分钟
Using features of the inputs2分钟
Predicting class probabilities1分钟
Review of basics of probabilities6分钟
Review of basics of conditional probabilities8分钟
Using probabilities in classification2分钟
Predicting class probabilities with (generalized) linear models5分钟
The sigmoid (or logistic) link function4分钟
Logistic regression model5分钟
Effect of coefficient values on predicted probabilities7分钟
Overview of learning logistic regression models2分钟
Encoding categorical inputs4分钟
Multiclass classification with 1 versus all7分钟
Recap of logistic regression classifier1分钟
Reading2 个阅读材料
Slides presented in this module10分钟
Predicting sentiment from product reviews10分钟
Quiz2 个练习
Linear Classifiers & Logistic Regression10分钟
Predicting sentiment from product reviews24分钟
2
完成时间(小时)
完成时间为 2 小时

Learning Linear Classifiers

Once familiar with linear classifiers and logistic regression, you can now dive in and write your first learning algorithm for classification. In particular, you will use gradient ascent to learn the coefficients of your classifier from data. You first will need to define the quality metric for these tasks using an approach called maximum likelihood estimation (MLE). You will also become familiar with a simple technique for selecting the step size for gradient ascent. An optional, advanced part of this module will cover the derivation of the gradient for logistic regression. You will implement your own learning algorithm for logistic regression from scratch, and use it to learn a sentiment analysis classifier....
Reading
18 个视频 (总计 83 分钟), 2 个阅读材料, 2 个测验
Video18 个视频
Intuition behind maximum likelihood estimation4分钟
Data likelihood8分钟
Finding best linear classifier with gradient ascent3分钟
Review of gradient ascent6分钟
Learning algorithm for logistic regression3分钟
Example of computing derivative for logistic regression5分钟
Interpreting derivative for logistic regression5分钟
Summary of gradient ascent for logistic regression2分钟
Choosing step size5分钟
Careful with step sizes that are too large4分钟
Rule of thumb for choosing step size3分钟
(VERY OPTIONAL) Deriving gradient of logistic regression: Log trick4分钟
(VERY OPTIONAL) Expressing the log-likelihood3分钟
(VERY OPTIONAL) Deriving probability y=-1 given x2分钟
(VERY OPTIONAL) Rewriting the log likelihood into a simpler form8分钟
(VERY OPTIONAL) Deriving gradient of log likelihood8分钟
Recap of learning logistic regression classifiers1分钟
Reading2 个阅读材料
Slides presented in this module10分钟
Implementing logistic regression from scratch10分钟
Quiz2 个练习
Learning Linear Classifiers12分钟
Implementing logistic regression from scratch16分钟
完成时间(小时)
完成时间为 2 小时

Overfitting & Regularization in Logistic Regression

As we saw in the regression course, overfitting is perhaps the most significant challenge you will face as you apply machine learning approaches in practice. This challenge can be particularly significant for logistic regression, as you will discover in this module, since we not only risk getting an overly complex decision boundary, but your classifier can also become overly confident about the probabilities it predicts. In this module, you will investigate overfitting in classification in significant detail, and obtain broad practical insights from some interesting visualizations of the classifiers' outputs. You will then add a regularization term to your optimization to mitigate overfitting. You will investigate both L2 regularization to penalize large coefficient values, and L1 regularization to obtain additional sparsity in the coefficients. Finally, you will modify your gradient ascent algorithm to learn regularized logistic regression classifiers. You will implement your own regularized logistic regression classifier from scratch, and investigate the impact of the L2 penalty on real-world sentiment analysis data....
Reading
13 个视频 (总计 66 分钟), 2 个阅读材料, 2 个测验
Video13 个视频
Review of overfitting in regression3分钟
Overfitting in classification5分钟
Visualizing overfitting with high-degree polynomial features3分钟
Overfitting in classifiers leads to overconfident predictions5分钟
Visualizing overconfident predictions4分钟
(OPTIONAL) Another perspecting on overfitting in logistic regression8分钟
Penalizing large coefficients to mitigate overfitting5分钟
L2 regularized logistic regression4分钟
Visualizing effect of L2 regularization in logistic regression5分钟
Learning L2 regularized logistic regression with gradient ascent7分钟
Sparse logistic regression with L1 regularization7分钟
Recap of overfitting & regularization in logistic regression分钟
Reading2 个阅读材料
Slides presented in this module10分钟
Logistic Regression with L2 regularization10分钟
Quiz2 个练习
Overfitting & Regularization in Logistic Regression16分钟
Logistic Regression with L2 regularization16分钟
3
完成时间(小时)
完成时间为 2 小时

Decision Trees

Along with linear classifiers, decision trees are amongst the most widely used classification techniques in the real world. This method is extremely intuitive, simple to implement and provides interpretable predictions. In this module, you will become familiar with the core decision trees representation. You will then design a simple, recursive greedy algorithm to learn decision trees from data. Finally, you will extend this approach to deal with continuous inputs, a fundamental requirement for practical problems. In this module, you will investigate a brand new case-study in the financial sector: predicting the risk associated with a bank loan. You will implement your own decision tree learning algorithm on real loan data....
Reading
13 个视频 (总计 47 分钟), 3 个阅读材料, 3 个测验
Video13 个视频
Intuition behind decision trees1分钟
Task of learning decision trees from data3分钟
Recursive greedy algorithm4分钟
Learning a decision stump3分钟
Selecting best feature to split on6分钟
When to stop recursing4分钟
Making predictions with decision trees1分钟
Multiclass classification with decision trees2分钟
Threshold splits for continuous inputs6分钟
(OPTIONAL) Picking the best threshold to split on3分钟
Visualizing decision boundaries5分钟
Recap of decision trees分钟
Reading3 个阅读材料
Slides presented in this module10分钟
Identifying safe loans with decision trees10分钟
Implementing binary decision trees10分钟
Quiz3 个练习
Decision Trees22分钟
Identifying safe loans with decision trees14分钟
Implementing binary decision trees14分钟
4
完成时间(小时)
完成时间为 2 小时

Preventing Overfitting in Decision Trees

Out of all machine learning techniques, decision trees are amongst the most prone to overfitting. No practical implementation is possible without including approaches that mitigate this challenge. In this module, through various visualizations and investigations, you will investigate why decision trees suffer from significant overfitting problems. Using the principle of Occam's razor, you will mitigate overfitting by learning simpler trees. At first, you will design algorithms that stop the learning process before the decision trees become overly complex. In an optional segment, you will design a very practical approach that learns an overly-complex tree, and then simplifies it with pruning. Your implementation will investigate the effect of these techniques on mitigating overfitting on our real-world loan data set. ...
Reading
8 个视频 (总计 40 分钟), 2 个阅读材料, 2 个测验
Video8 个视频
Overfitting in decision trees5分钟
Principle of Occam's razor: Learning simpler decision trees5分钟
Early stopping in learning decision trees6分钟
(OPTIONAL) Motivating pruning8分钟
(OPTIONAL) Pruning decision trees to avoid overfitting6分钟
(OPTIONAL) Tree pruning algorithm3分钟
Recap of overfitting and regularization in decision trees1分钟
Reading2 个阅读材料
Slides presented in this module10分钟
Decision Trees in Practice10分钟
Quiz2 个练习
Preventing Overfitting in Decision Trees22分钟
Decision Trees in Practice28分钟
完成时间(小时)
完成时间为 1 小时

Handling Missing Data

Real-world machine learning problems are fraught with missing data. That is, very often, some of the inputs are not observed for all data points. This challenge is very significant, happens in most cases, and needs to be addressed carefully to obtain great performance. And, this issue is rarely discussed in machine learning courses. In this module, you will tackle the missing data challenge head on. You will start with the two most basic techniques to convert a dataset with missing data into a clean dataset, namely skipping missing values and inputing missing values. In an advanced section, you will also design a modification of the decision tree learning algorithm that builds decisions about missing data right into the model. You will also explore these techniques in your real-data implementation. ...
Reading
6 个视频 (总计 25 分钟), 1 个阅读材料, 1 个测验
Video6 个视频
Strategy 1: Purification by skipping missing data4分钟
Strategy 2: Purification by imputing missing data4分钟
Modifying decision trees to handle missing data4分钟
Feature split selection with missing data5分钟
Recap of handling missing data1分钟
Reading1 个阅读材料
Slides presented in this module10分钟
Quiz1 个练习
Handling Missing Data14分钟
4.7
428 个审阅Chevron Right
职业方向

53%

完成这些课程后已开始新的职业生涯
工作福利

83%

通过此课程获得实实在在的工作福利
职业晋升

11%

加薪或升职

热门审阅

创建者 SSOct 16th 2016

Hats off to the team who put the course together! Prof Guestrin is a great teacher. The course gave me in-depth knowledge regarding classification and the math and intuition behind it. It was fun!

创建者 CJJan 25th 2017

Very impressive course, I would recommend taking course 1 and 2 in this specialization first since they skip over some things in this course that they have explained thoroughly in those courses

讲师

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Carlos Guestrin

Amazon Professor of Machine Learning
Computer Science and Engineering
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Emily Fox

Amazon Professor of Machine Learning
Statistics

关于 University of Washington

Founded in 1861, the University of Washington is one of the oldest state-supported institutions of higher education on the West Coast and is one of the preeminent research universities in the world....

关于 Machine Learning 专项课程

This Specialization from leading researchers at the University of Washington introduces you to the exciting, high-demand field of Machine Learning. Through a series of practical case studies, you will gain applied experience in major areas of Machine Learning including Prediction, Classification, Clustering, and Information Retrieval. You will learn to analyze large and complex datasets, create systems that adapt and improve over time, and build intelligent applications that can make predictions from data....
Machine Learning

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