Machine Learning

Supplementary Material to Andrew Ng’s Machine Learning MOOC

Anirudh Technical , ,

Although the lecture videos and lecture notes from Andrew Ng‘s Coursera MOOC are sufficient for the online version of the course, if you’re interested in more mathematical stuff or want to be challenged further, you can go through the following notes and problem sets from CS 229, a 10-week course that he teaches at Stanford (which also happens to be the most enrolled course on campus). It’s not hard to end up with a 100% score on his MOOC which is obviously a (much) watered down version of the course he teaches at Stanford, at least in terms of difficulty. If you don’t believe me, just have a go at the problem sets from the links below.

Lecture Notes

Section Notes

Handouts and Problem Sets

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Solutions to Machine Learning Programming Assignments

Anirudh Technical , , , , , ,

This post contains links to a bunch of code that I have written to complete Andrew Ng’s famous machine learning course which includes several interesting machine learning problems that needed to be solved using the Octave / Matlab programming language. I’m not sure I’d ever be programming in Octave after this course, but learning Octave just so that I could complete this course seemed worth the time and effort. I would usually work on the programming assignments on Sundays and spend several hours coding in Octave, telling myself that I would later replicate the exercises in Python.

If you’ve taken this course and found some of the assignments hard to complete, I think it might not hurt to go check online on how a particular function was implemented. If you end up copying the entire code, it’s probably your loss in the long run. But then John Maynard Keynes once said, ‘In the long run we are all dead‘. Yeah, and we wonder why people call Economics the dismal science!

Most people disregard Coursera’s feeble attempt at reigning in plagiarism by creating an Honor Code, precisely because this so-called code-of-conduct can be easily circumvented. I don’t mind posting solutions to a course’s programming assignments because GitHub is full to the brim with such content. Plus, it’s always good to read others’ code even if you implemented a function correctly. It helps understand the different ways of tackling a given programming problem.

ex1
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Enjoy!

 

Teach Yourself Machine Learning the Hard Way!

Anirudh Non Technical , , ,

This formula is kick-ass!

Darshan Hegde

It has been 3 years since I have steered my interests towards Machine Learning. I had just graduated from college with a Bachelor of Engineering in Electronics and Communication Engineering. Which is, other way of saying that I was:

  • a toddler in programming.
  • little / no knowledge of algorithms.
  • studied engineering math, but it was rusty.
  • no knowledge of modern optimization.
  • zero knowledge of statistical inference.

I think, most of it is true for many engineering graduates (especially, in India !). Unless, you studied mathematics and computing for undergrad.

Lucky for me, I had a great mentor and lot of online materials on these topics. This post will list many such materials I found useful, while I was learning it the hard way !

All the courses that I’m listing below have homework assignments. Make sure you work through each one of them.

1. Learn Python

If you are new to programming…

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Scatter Plot Bug Fix in Dato’s GraphLab Create ML Package in Python

Anirudh Technical , , , , , ,

I have been using Dato’s GraphLab Create for Coursera’s new Machine Learning Specialization that uses Python. Like me, if you’ve been facing trouble obtaining scatter plots on your canvas in GraphLab Create despite the following code:

graphlab.canvas.set_target('ipynb')

…then no worries, there is a quick fix. I’ve been deliberately lousy with the presentation, so sorry about that. Chances are that no one’s going to end up reading this anyway. I saw this problem being discussed on a Dato forum, so I decided to blog about the fix.

EDIT: Note that this problem is in GraphLab Create v1.6 only. They came up with v1.6.1 a few days after the problem was escalated on their forum, so a good option would be to upgrade GraphLab Create.

The problem you face should looks something like this (click images below to enlarge):Screenshot from 2015-09-25 14:10:20

To solve the problem:

Locate sframe.py from your home directory by searching for it from your desktop environment (applies to Windows users too). I found it in the following path on my computer:

~/anaconda/lib/python2.7/site-packages/graphlab/canvas/views

The file sframe.py should look like this:

Screenshot from 2015-09-25 15:49:44

Then replace the code in lines 255-227 of the opened .py file with the code highlighted below:

Screenshot from 2015-09-25 15:53:19

This should take care of the problem for good.

Now you have your desired result:

Screenshot from 2015-09-25 16:18:41

Machine Learning — New Coursera Specialization from the University of Washington

Anirudh Non Technical , , , , , , , , , ,

I have finally embarked on my first machine learning MOOC / Specialization. I love Python, and this course uses Python as the language of choice. Also, the instructors assert that Python is widely used in industry, and is becoming the de facto language for data science in industry. They use IPython Notebook in their assignments and videos.

The specialization offered by the University of Washington consists of 5 courses and a capstone project spread across about 8 months (September through April). The specialization’s first iteration kicked off yesterday.

washingtonMachineLearningThe first course, Machine Learning Foundations: A Case Study Approach is 6 weeks long, running from September 22 through November 9.

The Instructors:

Emily Fox and Carlos Guestrin
EmilyFoxguestrin-dato

Key Learning Outcomes
– Identify potential applications of machine learning in practice.
– Describe the core differences in analyses enabled by regression, classification, and clustering.
– Select the appropriate machine learning task for a potential application.
– Apply regression, classification, clustering, retrieval, recommender systems, and deep learning.
– Represent your data as features to serve as input to machine learning models.
– Assess the model quality in terms of relevant error metrics for each task.
– Utilize a dataset to fit a model to analyze new data.
– Build an end-to-end application that uses machine learning at its core.
– Implement these techniques in Python.

Week-by-Week
Week 1: Introductory welcome videos and the instructors’ views on the future of intelligent applications
Week 2: Predicting House Prices (Regression)
Week 3: Classification (Sentiment Analysis)
Week 4: Clustering and Similarity: Retrieving Documents
Week 5: Recommending Products
Week 6: Deep Learning: Searching for Images

EDIT

It’s been 3 days since the course began, and here’s how the classmate demographic looks like:

Classmates09252015

Statistics: The Sexiest Job of the Decade

Anirudh Non Technical , , , , , ,

Anyone who’s got a formal education in economics knows who Hal Varian is. He’s most popularly known for his book Intermediate Economics. He’s also the Chief Economist at Google. He is known to have famously stated more or less, that statisticians and data analysts would be the sexiest jobs of the next decade.

That has come true, to a great extent, and we’ll be seeing more.

Great places to learn more about data science and statistical learning:
1] Statistical Learning (Stanford)
2] The Analytics Edge (MIT)

In a paper called ‘Big Data: New Tricks for Econometrics‘, Varian goes on to say that:

In fact, my standard advice to graduate students these days is “go to the computer science department and take a class in machine learning.” There have been very fruitful collaborations between computer scientists and statisticians in the last decade or so, and I expect collaborations between computer scientists and econometricians will also be productive in the future.

See Also: Slides on Machine Learning and Econometrics

Getting Started

Anirudh Technical , , , , , ,

I have been searching for good MOOCs to get me started with R and Python programming languages. I’ve already begun the Johns Hopkins University Data Science Specialization on Coursera. It consists of 9 courses (including Data Scientist’s Toolbox, R programming, Getting and Cleaning Data, Exploratory Data Analysis, Reproducible Research, Statistical Inference, Regression Models, Practical Machine Learning and Developing Data Products), ending with a 7-week Capstone Project that I’m MOST excited about. I want to get there fast.

The Capstone would consist of :
  • Building a predictive data model for analyzing large textual data sets
  • Cleaning real-world data and perform complex regressions
  • Creating visualizations to communicate data analyses
  • Building a final data product in collaboration with SwiftKey, award-winning developer of leading keyboard apps for smartphones

I started with the R programming course where I found the programming assignments to be moderately difficult. They were good practice and also time-consuming for me since I haven’t yet gotten used to the R syntax, which is supposedly unintuitive. Anyway, I completed the course with distinction (90+ marks) scoring 95 on 100, losing 5 because I hadn’t familiarized myself with Git / GitHub. I did this course for a verified certificate, which cost me $29, and looks like this:

Coursera rprog 2015

I won’t be paying for any of the remaining courses though, but still will get a certificate of accomplishment for each course I pass. I have alredy begun with Getting and Cleaning Data and Data Scientist’s Toolbox.

I checked today, and it seems Andrew Ng’s Machine Learning course has gone open to all and is self-paced. A lot of people have gone on to participate in Kaggle competitions with what they learnt in his course, so I’d like to experience it — even though it’s taught with Octave / MATLAB. My very short term goal is to start participating in these competitions ASAP.

Kaggle Competitions

I will be learning the basics of Git this week and along with that, about reading from MySQL, HDF5, the web and APIs. I intend to start reading Trevor Hastie’s highly recommended book, Introduction to Statistical Learning.

ISL Cover 2

[DOWNLOAD LINK TO THE BOOK]

Meanwhile, I need to get started with Git and GitHub too, and I found a very useful blog by Kevin Markham and his short concise videos are great introductory material.

Incidentally, I was in a dilemma whether to start with Hastie’s material or Andrew Ng’s course first. This is what Kevin had to say

Hastie or Ng

The only reason I have reservations against Andrew Ng’s course is that its instruction isn’t in R or Python. Also, CTO and co-founder of Kaggle, Ben Hamner mentions here how useful R and Python are vis-à-vis Matlab / Octave.

Ben Hamner on Python R Matlab v2