## (note (code cslai))

Notes on codes, projects and everything

# Machine Learning

• ### Regression with 2-means clustering Annoy (non-scientific)

So apparently Annoy is now splitting points by using the centroids of 2 means clustering. It is claimed that it provides better results for ANN search, however, how does this impact regression? Purely out of curiosity, I plugged a new point splitting function and generated a new set of points.

(more…)
• ### Regression with Annoy (cont’d)

After a year and half, a lot of things changed, and annoy also changed the splitting strategy too. However, I always wanted to do a proper follow up to the original post, where I compared boosting to Annoy. I still remember the reason I started that (flawed) experiment was because I found boosting easy.

(more…)
• ### Quick experiment, boosting vs annoy

While following through the Statistical Learning course, I came across this part on doing regression with boosting. Then reading through the material, and going through it makes me wonder, the same method may be adapted to Erik Bernhardsson‘s annoy algorithm.

(more…)
• ### Further Hack on the Multi-Dimensional Approximate Neighbour Search

Traversing a tree structure often involves writing a recursive function. However, Python isn’t the best language for this purpose. Therefore I started flattening the tree into a key-value dictonary structure. Logically it is still a tree, but it is physically stored as a dictionary. Therefore it is now easier to write a simple loop to traverse it.

• ### Approximate Neighbour Search in Multiple Dimensions

In the previous post, I re-implemented Annoy in 2D with some linear algebra maths. Then I spent some time going through some tutorial on vectors, and expanded the script to handle data in 3D and more. So instead of finding gradient, the perpendicular line in the middle of two points, I construct a plane, and find the distance between it and points to construct the tree.

• ### Re-implementing Approximate Nearest Neighbour Search

Recently I switched my search code to Annoy because the input dataset is huge (7.5mil records with 20k dictionary count). It wasn’t without issues though, however I would probably talk about it next time. In order to figure out what each parameters meant, I spent some time watching through the talk given by the author @fulhack.

• ### Random notes on Pandas and Scikit-learn

So I first heard about Panda probably a year ago when I was in my previous job. It looked nice, but I didn’t really get the chance to use it. So practically it is a library that makes data looks like a mix of relational database table and excel sheet. It is easy to do query with it, and provides a way to process it fast if you know how to do it properly (no, I don’t, so I cheated).

## Random Posts

• ### Oh NO! My print output is chopped!

So my cheat with dask worked fine and dandy, until I started inspecting the output (which was to be used as an input for another script). While the script seemed to work fine, however when I started to parse each line I was hit with some funny syntax errors. After some quick inspection I found some of the lines was not printed completely.

I am currently doing some organization to my blogs. Few weeks ago, after spending months struggling to work in Ubuntu 7.10, I learned about symbolic links. Then I thought this would be good for my project file management. Therefore I started to re-organize my project file structure to utilize symbolic links. One of the projects that uses symbolic link is the current wordpress theme.

• ### Revisiting semantic web (plus wheel building with Poetry)

Back then, when I was still working on my postgraduate degree research, I used RDF, which was the preferred format in the world of Semantic Web to represent data. I eventually dropped the degree, and stopped following the development of the related technology and standards. Until I volunteered to update the import script for popit when I was looking for the next job/project.

(more…)
• ### Resource Definition Framework

As the name implies, Resource Definition Framework, or RDF in short, is a language to represent information about resources in world wide web. Information that can be represented is mostly metadata like title (assuming the resource is a web-page), author, last modified date etc. Besides representing resource that is network-accessible, it can be used to represent things that cannot be accessed through the network, as long as it can be identified using a URI.

• ### Sorting Multilingual Data

Been trying my best to stick to the well-known UNIX Philosophy – “Do one thing and do it well”, so I have been breaking down my projects into numerous pieces of small tasks and rely on existing tools whenever possible. One of the existing tool that I use a lot is the GNU sort tool. Generally sort utility is really doing fine and dandy without having to configure anything, at least not until I realize the problem that leads to this post.