## (note (code cslai))

Notes on codes, projects and everything

# 2016

• ### 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.

• ### Information Retrieving with ….. a lot of libraries

Implementing a Information Retrieval system is a fun thing to do. However, doing it efficiently is not (at least to me). So my first few attempts didn’t really end well (mostly uses just Go/golang with some bash tricks here and there, with or without a database). Then I jumped back to Python, which I am more familiar with and was very surprised with all the options available. So I started with Pandas and Scikit-learn combo.

## Random Posts

• ### 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.

• ### 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.

• ### Yet another Instant Messaging service

I have recently made my Adium useless by moving all my IM accounts to my beloved Nokia N9. While moving my buddy lists of all major instant messaging services, I did a quick check on each of the contact to see past interaction. It is sort of surprising to see I don’t actually chat with them as frequent as I thought, so why do I “need” my Adium opened all the time?

• ### Generating grids in javascript

Recently I find some of my pet projects share a common pattern, they all are based on some kind of grids. So I find myself writing similar piece of code over and over again. While re-inventing wheels is quite fun, especially when you learn new way of getting things done with every iteration, it is actually quite tedious after a while.

• ### The Little Pythoner, Part I

I saw this article from alistapart, which is about Javascript’s prototypal object orientation. So the article mentioned Douglas Crawford, and I was immediately reminded about my struggle in understanding the language itself. Back then I used to also refer to his site for a lot of notes in Javascript. So I went back to have a quick read, and found this article that discusses the similarity between Javascript and Lisp.