A PyTorch model is trained on public Hacker News data, embedding posts and comments into a high-dimensional vector space, using the mean squared error (MSE) of dot products as the loss function. The resulting model is reasonably good at finding similar posts and recommending posts for users.

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rxe is a thin wrapper around Python's re module. The various rxe functions are wrappers around corresponding re patterns. For example, rxe.digit().one_or_more('a').whitespace() corresponds to \da+\s. Because rxe uses parentheses but wants to avoid unnamed groups, the internal (equivalent) representation is actually \d(?:a)+\s. This pattern can always be retrieved with get_pattern().

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I will show how to solve the standard A x = b matrix equation with PyTorch. This is a good toy problem to show some guts of the framework without involving neural networks.

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Over a period of 6 months, we rolled out a Machine Learning model to predict a customer’s delivery (latitude, longitude). During the recent holiday peak, this ML model handled most of Fetchr’s order scheduling.

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2018 was a hot year for Data Science and AI. Here we picked out 5 highlights, which in our opinion shaped the field in the past year.

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Sometimes, the seven gods of data science, Pascal, Gauss, Bayes, Poisson, Markov, Shannon and Fisher, all wake up in a good mood, and things just work out. Recently we had such an occurence at Fetchr, when the Operational Excellence team posed the following question: if we could pick our Saudi warehouse locations, where would be put them? What is the ideal number of warehouses, and, what does ideal even mean? Also, what should our “delivery radius” be?

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Previously I wrote two articles about data infra and data engineering at Fetchr. This time I want to move up the stack and talk about a simple piece of metrics engineering that proved to be very impactful: Growth Accounting and Backtraced Growth Accounting.

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A description of our Analytics+ML cluster running on AWS, using Presto, Airflow and Superset.

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Warren Buffett says deciding what not to spend time on is just as important as deciding what to spend time on.

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When working with averages, we have to be careful. There are pitfalls lurking to pollute our statistics and results reported.

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We used Hive/Presto on AWS together with Airflow to rapidly build out the Data Science Infrastructure at Fetchr in less than 6 months.

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I used to think that a good analogy for using data is the instrumentation of a cockpit in an airliner. Lots of instruments, and if they fail, the pilot can’t fly the plane and bad things happen. There’s no autopilot for companies. The problem with this analogy is that planes aren’t built in mid-air. Product teams and companies constantly need to build and ship new products.

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I gave this talk at the O’Reilly Strata Conference London in 2016 June, mostly based on what I learned at Prezi from 2012-2016.

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I read this book on my first vacation after I started working at Facebook and thus became a semi-regular Hack/HHVM user. I highly recommend reading (parts of) it. But not to learn Hack/PHP, which is irrelevant to most people. Instead, it’s to learn about how Facebook improved it’s www codebase and performance without rewriting the old PHP code in one big effort, and thus avoided the famous Second-system effect.

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This post is about the amazing success of Einstein's general theory of relativity. The theory predicts, among other things the accelerating Universe, black holes, gravitational lensing and gravitational waves. The real shocker is to remember that Einstein didn't invent general relativity to explain these. He didn’t know about these, they didn't exist at that time!

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Most bets businesses take, be it hiring, features, products or strategy don't work out. Still, many businesses are successful despite setbacks. A negative attitude---even when the analysis of the situation is in fact correct---may be missing the bigger picture.

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For the past 2 months I've been using Cloud9 for writing code in the cloud, and I can wholeheartedly recommend it: it just works for me. It's basically Docker plus an IDE: you get a Docker container running Ubuntu that you can access over a web IDE.

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A spreadsheet comparing the three opensource workflow tools for ETL.

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Pinball is an ETL tool written by Pinterest. Like Airflow, it supports defining tasks and dependencies as Python code, executing and scheduling them, and distributing tasks across worker nodes. It supports calendar scheduling (hourly/daily jobs, also visualized on the web dashboard). Unfortunately, I found Pinball has very little documentation, very few recent commits in the Github repo and few meaningful answers to Github issues by maintainers, while it's architecture is complicated and undocumented.

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Make a simple blog with Github Pages and Pelican.

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