Notes on codes, projects and everything
2016 January
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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.
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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.
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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.
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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
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Dragon Curve
I really don’t know how to start explaining what is a Dragon Curve. However, I find it is interesting enough after finding out that there’s actually a fixed pattern of occurrence. Therefore I spent some time writing a series of scripts to plot the generated fractal into a graph. What I didn’t expect is, the series get really complicated after a while.
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jQuery holdEvent
The making of this plugin was completely a random act of hand-itchiness. A friend of mine (@cornguo) published a fun app online. There is a name for this kind of app, but I can’t recall at the moment. It typically displays some buttons (usually in a grid), and clicking them causes some sound to be played. The interesting part in cornguo’s app is that there’s a text-input field where the name of the buttons can be typed-in for replaying.
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Some status updates
There are a lot of things I want to post to both here and my personal blogs. However I was sucked into sanctuary for the most of last month. I guess after a month of playing, it is probably time to slowly resume my personal projects.
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Imperfect Reimplementation of Lists in PHP
Long long time ago when I was working with Prolog, I was introduced to list. Unlike arrays in most popular programming languages, we weren’t really able to access to a particular member directly. Every list is constructed in a chain-like structure.
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Estimating the value of pi with a line of Python
I came across a video on Youtube on Pi day. Coincidently it was about estimating the value of Pi produced by Matt Parker aka standupmaths. While I am not quite interested in knowing the best way to estimate Pi, I am quite interested in the algorithm he showed in the video however. Specifically, I am interested to find out how easy it is to implement in Python.
