A few months ago, I saw this post by Chris Krycho on Hackernews, which points out just how easy it can be to share Rust binaries with friends. The use case really spoke to me — I spend a lot of time building prototypes and I often need to share my prototypes with a few… Read More Rust: Cross compiling from Ubuntu to OS X
A few years ago, I wrote about how to analyze the 2012 California Health Interview Survey in R. In 2012, plans for Covered California (Obamacare in California) were just beginning to take shape. Today, Covered California is a relatively mature program and it is arguably the most successful implementation of the Affordable Care Act in… Read More Analyzing the 2015 California Health Interview Survey in R
In this post, we’ll look at a simple method to identify segments of an image based on RGB color values. The segmentation technique we’ll consider is called color quantization. Not surprisingly, this topic lends itself naturally to visualization and R makes it easy to render some really cool graphics for the color quantization problem. The… Read More Color Quantization in R
On average, Twitter users worldwide generate about 6,000 tweets per second. Obviously, there is much interest in extracting real-time signal from this rich but noisy stream of data. More generally, there many open and interesting problems in using high-velocity streaming text sources to track real-time events. In this post, I describe the key components of… Read More Building a Streaming Search Platform
This post is a follow up to my last post on quadratic programming facilities in R. A commenter pointed me to the ipoptr project which exposes an R interface to the COIN-OR optimization routine Ipopt. COIN-OR is a suite of optimization utilities implemented in C++ and supported by a back-end of configurable FORTRAN linear system… Read More Sparse Quadratic Programming with Ipoptr
This post is another tour of quadratic programming algorithms and applications in R. First, we look at the quadratic program that lies at the heart of support vector machine (SVM) classification. Then we’ll look at a very different quadratic programming demo problem that models the energy of a circus tent. The key difference between these… Read More More on Quadratic Programming in R
The California Health Interview Survey (CHIS) is a remarkable biannual survey of health status, care access, and demographics for California residents. The 2011-2012 public use survey data has recently been released and is freely available after registering at the CHIS site. CHIS currently offers data in SAS, Stata, and SPSS formats. However, thanks to a… Read More Analyzing the 2011-2012 California Health Inteview Survey with R
The MathWorks has an interesting demo on how the shape of a circus tent can be modeled as the solution of a quadratic program in MATLAB. In this post, we’ll show how to solve this same problem in R using the quadprog package and also provide the technical details not covered in the Mathwork’s example.… Read More The Circus Tent Problem with R’s Quadprog
R’s igraph package provides a simple and flexible set of utilities for working with graphs. In this post, we’ll use this package to animate the simulated spread of a disease through a network. Graphs A graph is just a collection of nodes joined by edges: require(igraph) # Specify an undirected graph by hand, using a… Read More Going viral with R’s igraph package
In this post, we’ll explore a special type of nonlinear constrained optimization problems called quadratic programs. Quadratic programs appear in many practical applications, including portfolio optimization and in solving support vector machine (SVM) classification problems. There are several packages available to solve quadratic programs in R. Here, we’ll work with the quadprog package. Before we… Read More Solving Quadratic Progams with R’s quadprog package