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All around the world at noon GMT on April 28, data scientists around the world will compete in the world's first one-day International Data Science Hackathon, organized by Data Science London. Participants will receive a data set at the beginning of the event, and work in teams of 3-5 over the ... [Read more...]

In this post, I want to address the following issue: several data files with a common trame have to be dealt with by an R function. The function should export files (such as images or data files or any other file type). I explain how to create filenames such that ... [Read more...]

I’m currently working my way through Rasmussen and Williams’s book on Gaussian processes. It’s another one of those topics that seems to crop up a lot these days, particularly around control strategies for energy systems, and thought I should be able to at least perform basic analyses ... [Read more...]

This post by Suraj Gupta explains it all. This is the firs time I have seen a  concise and accessible explanation of the R environment structure and why it matters.   Addendum: This one by Digithead is also pretty good [Read more...]

Most of the time when we're programming in R, we don't think about how R gets from an object name (say, "stdev") to what it represents (a function to calculate standard deviation, perhaps). If you're writing functions, you've probably know about R's lexical scoping. And if you use a lot ... [Read more...]

That's a mouthful! I presented this topic to a group of Vandy statisticians a few days ago. My notes (essentially reproduced in this post) are recorded at the Dept. of Biostatistics wiki: HowToBootstrapCorrelatedData. The presentation covers some bootstrap strategies for hierarchically structured (correlated) data, but focuses on the multi-stage bootstrap; ... [Read more...]

Wondering about the question I posted on Friday (on StackExchange, no satisfactory answer so far!), I looked further at the special case of the gamma distribution I suggested at the end. Starting from the moment conditions, and the solution is (hopefully) given by the system The resolution of this system ... [Read more...]

I am quite interested in both Wars with sabres and Sabremetric WARs but the War I am most involved in is the card game. Unfortunately, it is one my six year old favourites and he is quite happy to while away the hours (literally) playing it with anyone pressganged into ... [Read more...]

Marketing is one of the pioneering domains when it comes to applications of predictive analytics to Big Data. (For example, how Target used statistical modeling to predict demographic attribues of customers, like pregnancy, to target coupons.) To get such powerful insights into the hands of marketers, DC-area company LityxIQ provides ... [Read more...]

I want to introduce the Transaction Cost and Execution Price functionality in the Backtesting library in the Systematic Investor Toolbox. The Transaction Cost is implemented by a commission parameter in the bt.run() function. You may specify the commissions in $ per share for “share” type backtest and as a percentage ... [Read more...]

Web-scraping, or web-crawling, sounds like a seedy activity worthy of an Interpol investigative department. The reality, however, is far less nefarious. Web-scraping is any procedure by which someone extracts data from the internet. Given that it’s possible to get the internet on computers these days; web-scrapping opens an array ... [Read more...]

pie( table( whence.i.tweet )) qplot( whence ) + coord_polar() pie( log( table( whence )))+RColorBrewer ggplot (see below) plot( density( tweets.len )) qplot(... stat="density") + geom_density qplot(...stat="bin") + geom_text(...) tweeple tweep... [Read more...]

You probably already knew that you can draw mathematical equations in Google by typing the equation into the search box. For example, here's the Standard Normal density function: I can't find a way to embed the graph directly, but if you click on it you'll find it's interactive: you can ... [Read more...]

In this article, you will find a list of Internet resources that may be useful if you are programming in R. If you have a problem with R and [Read more...]

In this post I use OpenStreetsMaps and ggplot2 to plot geographically were psychologists live, using data from a facebook document. [Read more...]

Hadley Wickham (@hadleywickham) this week mentioned on Twitter his preference for saveRDS() over the more familiar save(). Being a new function to me, I thought I’d take a look… save() and load() will be familiar to many R users. They … Continue reading → [Read more...]

This is a simple apps, called “Draw Your Breast with R“  created with R to generate Breast alike graphics. With this Draw Your Breast with R apps, you can change 4 parameters which are Theta, Phi, Expand and Color to generate graphics like... [Read more...]

I searched PubMed for several major DSM-IV disorders and downloaded the hits. Using ggplot2 I plotted the number of publications each year for each disorder. [Read more...]

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