Understanding the mathematics behind collaborative filtering models for recommendation engines

I highly recommend checking out one of my other posts as an introduction to recommendation engines:

Collaborative filtering is a type of recommendation engine that uses both user and item data. More specifically, ratings from individual users on individual items. This way, items are recommended based on the ratings from other users, thus, collaborative. This data can be represented in a utility matrix, with one axis being users and one axis being items. …


What they are, how they work, and why they’re great.

Recommendation engines are everywhere now. Almost any app you use incorporates some sort of recommendation system to either push new content or drive sales. Recommendation engines are Netflix telling you what you should watch next, the ads on Facebook pushing products that you just happened to look at once, or even Slack suggesting which organization channels you should join. The advent of big data and machine learning has made recommendation engines one of the most directly applicable aspects of Data Science.

Let’s say your friend asks you for a movie recommendation. How do you go about doing this? If you’re…


Using Python to answer that age-old question.

So I’ve been a lifelong Pokémon fan and a recently-converted Computer Science nerd. While my main interest lies in Data Science (plug for my last post on the Ethics of Data Science), I find myself thinking up random coding projects all the time, most of which never come to fruition.

I was working on a classification project with my friend Augustine Chang and while looking at a scatterplot of our data, we saw a familiar silhouette.

As a joke, we overlaid images of Pokémon onto our graphs in our presentation slides to look like it was some fun matplotlib


The Ethics of Data Science

(from: robynmac on Depositphotos)

The notion of ethics in Data Science first occurred to me when I was learning how to scrape the web for data. Newly-equipped with the ability to easily capture and store any information merely printed online, I was having fun scraping different websites just for the sake of it. Then, upon trying to scrape Reddit, I got this message:


I’m a huge fan of Google’s hardware. My previous and current phones are the Pixel 2XL and the Pixel 3XL. Prior to that, I was a diehard iPhone user so — what got me to make the switch?

I take a lot of pictures. Before this year, whenever I travelled I’d bring a DSLR, a GoPro with a gimbal and sometimes a drone. I always had an additional bag to carry all my cameras, extra batteries and all the chargers. When the second-generation Google Pixels were announced and started topping all the lists for having ‘the best smartphone camera’, I…

Yish Lim

Data Scientist | Machine Learning Engineer https://www.linkedin.com/in/yishuen-lim/

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