August 2013

StarCluster and R

August 31, 2013 | 0 Comments

StarCluster is a utility for creating and managingdistributed computing clusters hosted on Amazon's Elastic ComputeCloud (EC2). StarCluster utilizes Amazon´s EC2 web service to createand destroy clusters of Linux virtual machines on demand. Justin Riley http://star.mit.edu/cluster/docs/latest/index.html StarCluster documentation StarCluster provides a convenient ... [Read more...]

Introducing ‘propagate’

August 31, 2013 | 0 Comments

With this post, I want to introduce the new ‘propagate’ package on CRAN. It has one single purpose: propagation of uncertainties (“error propagation”). There is already one package on CRAN available for this task, named ‘metRology’ (http://cran.r-project.org/web/packages/metRology/index.html). ‘propagate’ has some additional functionality ... [Read more...]

GitHub Package Ideas I Stole

August 31, 2013 | 0 Comments

One of my favorite sources of good ideas is looking at the GitHub repositories of others and modeling my repos after the good ideas I see others doing. Here's Steve Jobs on stealing ideas: In the past few weeks I've … Continue reading → [Read more...]

MLB Rankings Using the Bradley-Terry Model

August 31, 2013 | 0 Comments

Today, I take my first shots at ranking Major League Baseball (MLB) teams. I see my efforts at prediction and ranking an ongoing process so that my models improve, the data I incorporate are more meaningful, and ultimately my predictions are largely accurate. For the first attempt, let’s rank ... [Read more...]

Visualising Shrinkage

August 31, 2013 | 0 Comments

A useful property of mixed effects and Bayesian hierarchical models is that lower level estimates are shrunk towards the more stable estimates further up the hierarchy. To use a time honoured example you might be modelling the effect of a new teaching method on performance at the classroom level. Classes ... [Read more...]

Encouraging citation of software – introducing CITATION files

August 30, 2013 | 0 Comments

Summary: Put a plaintext file named CITATION in the root directory of your code, and put information in it about how to cite your software. Go on, do it now – it’ll only take two minutes! Software is very important in science – but good software takes time and effort that ... [Read more...]

The joy and martyrdom of trying to be a Bayesian

August 30, 2013 | 0 Comments

Some of my fellow scientists have it easy. They use predefined methods like linear regression and ANOVA to test simple hypotheses; they live in the innocent world of bivariate plots and lm(). Sometimes they notice that the data have odd histograms and they use glm(). The more educated ones use … ... [Read more...]

Tutorial: Parallel programming with foreach

August 30, 2013 | 0 Comments

Exegetic Analytics extols the wonders of foreach package for iterative operations that go beyond the standard "for" loop in R. For example, here's a neat (if not optimally efficient) construct using filters to calculate the primes less than 100: foreach(n = 1:100, .combine = c) %:% when (isPrime(n)) %do% n The open-source team ... [Read more...]

ECVP tutorial on classification images

August 30, 2013 | 0 Comments

The slides for my ECVP tutorial on classification images are available here. Try this alternative version if the equations look funny. (image from Mineault et al. 2009) The slides are in HTML and contain some interactive elements. They’re the result of experimenting with R Markdown, D3 and pandoc. You write ... [Read more...]

Making regex examples work for you!

August 30, 2013 | 0 Comments

One of the most frequently used string recognition algorithms out there is regex and R implements regex.  However, users can often be frustrated with how despite taking examples verbatim from many sources such as stackoverflow they do not seem to ... [Read more...]

Knitr/Markdown OpenCPU App

August 30, 2013 | 0 Comments

A new little OpenCPU app allows you to knit and markdown in the browser. It has a fancy pants code editor which automatically updates the output after 3 seconds of inactivity. It uses the Ace web editor with mode-r.js (thanks to RStudio for making the latter available). Like all OpenCPU ... [Read more...]

Plot Weekly or Monthly Totals in R

August 29, 2013 | 0 Comments

When plotting time series data, you might want to bin the values so that each data point corresponds to the sum for a given month or week. This post will show an easy way to use cut and ggplot2's stat_summary to plot month totals in R wi... [Read more...]

A simple amortization function

August 29, 2013 | 0 Comments

I was working on a project yesterday where I needed to amortize out a bunch of loans to calculate the total interest a borrower would pay if he or she paid the minimum monthly payment for the full term of the loan. I couldn’t find any package in R ... [Read more...]

R and Linear Algebra

August 29, 2013 | 0 Comments

by Joseph Rickert I was recently looking through upcoming Coursera offerings and came across the course Coding the Matrix: Linear Algebra through Computer Science Applications taught by Philip Klein from Brown University. This looks like a fine course; but why use Python to teach linear algebra? I suppose this is ... [Read more...]

Increasing Repeat Purchase Rate by Analyzing Customer Latency

August 28, 2013 | 0 Comments

For online businesses, Repeat Purchase Rate is one of the critical metrics of the business performance. Higher repeat purchase rate means more active members, and thus leads to higher profit. “Customer Latency refers to the average time between customer activity events, for example, making a purchase, calling the help desk, ... [Read more...]

TV Ratings Myths

August 28, 2013 | 0 Comments

TV Show Cancellations: Myths and Models TV shows are amazing ways to waste time and, on occasion, the story is so good that you actually start to care. The problem is that some shows get cancelled before they jump the shark. Classic examples are shows like Firefly or Arrested Development. ... [Read more...]
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