VARUNA JAYASIRI

@vpj

21 Habits I Picked Up While Learning Machine Learning

June 26, 2019

This is a list of practices I adopted along the way that I think are worth sharing.

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Transformer in Tensorflow - Attention Is All You Need

Feb 24, 2019

I coded this Transformer from scratch for learning. This is based on The Annotated Transformer by Harvard NLP, which uses PyTorch.

It is tested on a toy problem instead of NLP data to make things simpler.

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Proximal Policy Optimization Algorithms - PPO in PyTorch

Feb 9, 2019

This is a re-implementation of my previous Tensorflow PPO code. I just coded it to try out PyTorch. This is also fully documented and should help someone trying to learn about PPO.

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Lab: Organize Machine Learning Experiments

Dec 21, 2018

This library helps you organize machine learning experiments. It maintains TensorBoard summaries, checkpoints, produce pretty console outputs, and also adds a header with progress of experiments to python source files. It also has tools to plot custom charts based on TensorBoard summaries.

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Deeq Q Learning in Tensorflow

June 16, 2018

I coded a DQN agent to play Atari. It is a stand alone implementation. I went through the Open AI DQN so it's very similar to it. I coded this also in a literate fashion similar to my previous PPO implementation.

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Proximal Policy Optimization (PPO) in Tensorflow

June 3, 2018

I implemented a reinforcement learning agent using PPO to play Atari Breakout. It is a standalone implementation on TensorFlow.

I coded in a literate form with all the mathematical formula's etc, embedded in comments so that it can be used as a tutorial if any one wants to - and of course as a reference for my self.

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Turn TensorFlow functions into mathematical notations and diagrams

March 24, 2018

I started working on a bunch of helper classes to use TensorFlow on Jupyter notebooks.

They provide nice diagrams and mathematical formulas as outputs based on the TensorFlow operations. It helps you understand the code better, and also acts as an inline help when coding.

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Generative Adversarial Networks (Gaussian Distribution)

February 3, 2018

This is a very simple Generative Adversarial Network build with deeplearn.js on ObservableHQ.

I coded this as an experiment to try out ObservableHQ, because I've loved almost all the projects by its creators @jashkenas and @mbostock.

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Vanilla LSTM with numpy

October 8, 2017

I implemented a Long short-term memory (LSTM) module on numpy from scratch. This is for learning purposes. The network is trained with stochastic gradient descent with a batch size of 1 using AdaGrad algorithm (with momentum).

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Should we switch from CoffeeScript?

September 28, 2016

We are considering moving out codebase from CoffeeScript to TypeScript.

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Wallapatta editor spelling checker

April 30, 2016

I updated Wallapatta editor with a spellchecker.

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Open sourcing nearby.lk data models library

April 29, 2016

We did a re-write of the nearby.lk data model library, and we decided to open source the core of it. It supports JSON or YAML data files, and parses them based on a specification (like a schema).

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Page Breaks

April 27, 2016

In Wallaptta we model pagination as a cost minimization problem. That is, we try to find where to place page breaks so that there is no overflow and the cost is minimised. If the cost of adding a page break at a given point is know this can be easily solved with dynamic programming.

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A few node.js/Javascript performance tips

March 19, 2016

We want to share some node.js performance tips we found while working on Forestpin; specifically how to optimize runInContext, setting heap limits, memory usage with string slices, and joining strings.

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Wallapatta Update

December 01, 2015

I added full width blocks, and scripting to Wallapatta. Full width blocks are useful when adding large images, and we use embedded scripts to create diagrams.

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Parent in (sliced string)

November 23, 2015

We found that chrome (and therefor node.js) continues to keep the parent string in memory even if you discard it after taking a slice of it.

This is probably a optimization to make slicing efficient, and to reduce memory footprint - assuming you are keeping a reference to parent anyway.

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jsblocks, React, Angular performance compared with Weya.coffee

May 27, 2015

I came across jsblock yesterday on Hacker News. They had a nice performance comparison test case set comparing jsblocks with Angular and React. It made me curious to see how the small library we use (Weya.coffee) compares in performance with these.

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Small data preparation

May 24, 2015

This is a new project I'm working on. It helps parse data with different structures, like reports from legacy systems.

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Wallapatta Blog

May 18, 2015

I just started moving my blog from Svbtle to a static blog generator that I created. It is based on Wallapatta.

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Shared memory with Node.js

May 13, 2015

This is a tutorial on using shared memory among node.js processes.

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Getting the first B2B customer

August 11, 2014

It took Forestpin almost 2 years to get its first big customer. Making the first sale is always hard. It was a tough ride; talking to a lot of potential customers, changing product strategy from time to time, taking up classes on pitching and of course a lot of programming. We learned a lot during the process.

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Black or White

July 27, 2014

Which background is better? Most text editors and document readers have light backgrounds. But there's a lot of programmers who use dark backgrounds. And there are a some analytics and dashboard applications with dark backgrounds.

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SEO Crap

July 27, 2014

SEO is dead - at least much different from what it was known to be. But there are a plenty of consultants who market SEO, as if it is something that is hard to get right. Many organizations fall for it.

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2 to 10 times faster HTML animations

May 10, 2014

We figured that we can get a much higher frame rate by using webkit matrix3d transformations than using standard css properties, for animations

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Weya.coffee

March 19, 2014

Weya.coffee is a lightweight library with no dependencies to generate DOM elements. We developed it to replace Coffeecup as a client side template engine. Because of its simplicity and performance, we are also using Weya to replace DOM manipulation of d3.js in data visualizations.

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People who are really serious about software should write their libraries

February 19, 2014

We have been using a lot of tools and libraries in our software, and have replaced a number of them with our code. Libraries makes it easy to get things done, and to ship early. But from my experience, having a third-party library or a tool dominate a core part of your software is not a good idea.

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We stopped advertising on Facebook

December 30, 2013

nearby.lk stopped advertising on Facebook to get Facebook likes, because we felt that it was a giant fruitless scheme of making Facebook rich. Most of the likes on Facebook are useless, they are basically random clicks, which adds no value to anybody, and you need to pay Facebook for that. By the way, this may not be the case with advertising for Clicks to Website, Website Conversions, etc. - I don't have experience with those.

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Coffeescript helpers for d3.js

December 28, 2013

We developed a a small library called fp.js as a wrapper for d3.js dom creation code. It helps you have much more readable, cleaner code.

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Visualize data tables with variable length underlines

December 23, 2013

Underline doesn't take away space in a table or a list of data and by varying the length of the underline you can help readers scan much faster and get an idea of the data and its distribution without having to read each number.

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Another JS Framework

December 17, 2013

I started working on Sweet.js about a month ago. It is inspired by Backbone.js. Sweet.js supports HTML5 states, so that you don't have to go through work arounds like these. Sweet.js is not a MVC framework, but it has a views similar to Backbone.js, which supports inheritance without affecting events and initializations of super classes. And it's written in Coffeescript.

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Moving from Google Appengine to NodeJS on Amazon EC2

December 12, 2013

nearby.lk moved the servers from Google App engine to Amazon EC2 a couple of months back, and the backend is now built with nodejs with mongodb as the database.

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Coffeescript Macros

December 9, 2013

We are trying to have C like macros in CoffeeScript. Main motivator is to improve efficiency while keeping the code clean and maintanable.

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Forestpin Lite

December 1, 2013

We are releasing Forestpin Lite, with a lot of improvements to our previous Forestpin Lite version released at the 24th Fraud Conference in June. The new version is packaged as a Google Chrome offline application and therefore runs on Windows, Mac and Linux platforms. Chethiya Abeysinghe was behind Forestpin Lite.

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Forestpin Enterprise Redesign

November 27, 2013

We released the new version of Forestpin Enterprise last week. The new version is a complete rewrite of both the backend and UI. The backend was rewritten to be faster and to introduce a bunch of new features and analytics. The user interface was redesigned to be much more user friendly and also with focus on mobile devices such as tablets.

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Passing File Descriptors Between Processes Using Sendmsg() and Recvmsg()

January 11, 2011

Using this technique you can pass file descriptors between processes using sendmsg() and recvmsg() functions using UNIX Domain Protocol. Any descriptor can be passed using this method not just a file descriptor.

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TCP Echo Server Example in C++ Using Epoll

January 2, 2011

This example is a simple server which accepts connections and echos whatever data sent to the server. This example also demonstrates the use of epoll, which is efficient than poll. In epoll unlike poll all events that need to be monitored are not passed everytime the wait call is made.

Epoll uses event registration where events to be watched can be added, modified or removed. This makes it efficient when there are a large number of events to be watched.

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