Monthly Archives: March 2014

Singular Value Decomposition

In the Statistical Computing class I took last fall, a matrix decomposition called the singular value decomposition came up briefly as a way to classify similar objects. I wanted to learn more about it but I couldn’t find a resource that was exactly what I wanted, so I decided to create one. I wrote up two IPython Notebooks about singular value decomposition, one is an introduction to the concept and an example application to classifying research articles, the other deals with image compression. The notebooks are viewable at the links below. You can also download the code from these links:

Singular Value Decomposition and Applications

Singular Value Decomposition of an Image

Machine Learning Class

I recently started taking another online class, Machine Learning. Like the database class I took previously (blog entry) it is from Stanford. Unlike the database class, it is offered through coursera, a for-profit company co-founded by the Professor for the course, Andrew Ng. The for-profit aspect really came into focus when I got an email offering “Free $25 Promotional Code for Machine Learning Tutoring!”

The first few weeks covered a lot of things I was already familiar with, but I’m still enjoying hearing the material from a different angle. Although overall the course feels a bit less polished than the Database class, I’m really excited to be taking it and I’m looking forward to the next week of lectures.

Online Introduction to Databases class

I recently finished a free online course from Stanford on Databases (link to course webpage). It’s taught by Professor Jennifer Widom, who gives excellent lectures throughout the course. The exercises are well thought out and fun to do, and the online submission and grading system is very intuitive. Another nice feature is the “progress” tab, which shows a bar graph of all the points you’ve earned on each individual assignment, as well as your current total of points for the course. The progress graph makes writing SQL and XML queries feel like playing a video game.

I really enjoyed the challenge of thinking of ways to build up different sets using nested SQL queries. Besides just learning SQL for its own sake, taking the class has helped me understand the conventions behind some operations in other environments, for example dataframe joins in pandas. I definitely feel much more powerful in regards to accessing and manipulating data after taking the class.

I highly recommend the class. I imagine it will be offered again.