Notes on codes, projects and everything
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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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What’s so difficult about HTML?
I am not going to waste time telling stories that inspire this post, as most people would have already heard something similar constantly. This is not a mythbuster kinda post, so don’t expect a scientific proof to the answer of the question. Instead, through this post, I hope to break the impression that claims composing a HTML document is difficult.
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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?
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Evaluating logical statements
Often times one would have to write code to evaluate logical statements. For example, given statement p and q, what is p implies q? As there’s no operator for implication in PHP, one would have to rewrite the statement that consists only in NOT (
!), AND (&&) and OR (||) operators. When there are a huge load of these statements, code can be difficult to read. -
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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Working Environment Setup, for 2020
In recent years, I start to make my development environment decouple from the tools delivered by the package manager used by the operating system. The tools (compiler, interpreters, libraries etc) are usually best left unmodified so other system packages that rely on them keeps working as intended. Also another reason for the setup is I wanted to follow the latest release as much as possible, which cannot be done unless I enroll myself to a rolling release distro.
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