Third Milano R net meeting April 18, 2013 @ 6.00 PM Fiori Oscuri Bistrot & Bar Via Fiori Oscuri, 3 Milano Further details will be published shortly. Stay connected!

Third Milano R net meeting April 18, 2013 @ 6.00 PM Fiori Oscuri Bistrot & Bar Via Fiori Oscuri, 3 Milano Further details will be published shortly. Stay connected!

A friend of mine asked me the other day how she could use the function optim in R to fit data. Of course there are functions for fitting data in R and I wrote about this earlier. However, she wanted to understand how to do this from scratch using optim. The function optim provides algorithms for general...

There are many ways to simulate a multivariate gaussian distribution assuming that you can simulate from independent univariate normal distributions. One of the most popular method is based on the Cholesky decomposition. Let’s see how Rcpp and Armadillo perform on this task. #include <RcppArmadillo.h> // ] using namespace Rcpp; // ] arma::mat mvrnormArma(int n, arma::vec mu, arma::mat sigma) { int ncols...

as.character() is your friendas.character() is your friend Sometimes when you open a data file (lets say a .csv), variables will be recognized as factor whereas it should be numeric. It is therefore tempting to simply convert the variable to numeric using as.numeric(). Big mistake! If...

This is a repost of the second part of an example that I posted last year but at the time I only had the PDF document (written in ). This is the second example to generate multivariate random associated data. This example shows how to generate ordinal, categorical, data. It is a little more complex than generating continuous

On Friday I traveled to Boulder, CO to update the Boulder BI Brain Trust on the latest news and updates from Revolution R Enterprise. While I was there, I was interviewed by BBBT president Claudia Imhoff. In a wide-ranging chat, we discussed: What's behind the Revolution Analytics momentum over the past year? How Business Intelligence relates to Data Science...

I gave a talk at the Spring ENAR meetings this morning on some of the technical aspects of creating the book. The session was on reproducible research and the slides are here. I was dinged for not using git for version control (we used dropbox for simp...

If you follow me on Twitter, you know that I’m a big fan of RuPaul’s Drag Race. The transformation, the glamour, the sheer eleganza extravanga is something my life needs to interrupt the monotony of grad school. I was able to catch up on nearly four seasons in a little less than a month, and I’ve been watching the… Continue reading →

In the previous post, I forgot to show an example of Box-Cox transformation when there’s a lack of normality. The Box-Cox procedure computes values of which best “normalises” the errors. value Transformed value of Y 2 1 0.5 0 -0.5 -1 -2 For example: The plot indicates a log transformation. Matrix Representation We can use

This is a repost of an example that I posted last year but at the time I only had the PDF document (written in ). I’m reposting it directly into WordPress and I’m including the graphs. From time-to-time a researcher needs to develop a script or an application to collect and analyze data. They may also need

Recently I have used hexadecimal numbers in GNU R. The way they are parsed surprised me and is inconsistent with Java. As R Language Definition pdf only briefly mentions hexadecimal numbers here is what I have found.First I have checked the following c...

This is a test post since I want to improve upon Jeffrey Horner’s strategy for posting R code in Tumblr. The only minor improvement I wanted to try out is hosting the images directly on the web. I mean, right now the images won’t show in RSS readers. I’m not doing anything new at all, just using the...

I learned about Lord Rayleigh’s discovery of argon in my 2nd-year analytical chemistry class while reading “Quantitative Chemical Analysis” by Daniel Harris. (William Ramsay was also responsible for this discovery.) This is one of my favourite stories in chemistry; it illustrates how diligence in measurement can lead to an elegant and surprising discovery. I find

Call for participation: DMApps 2013 – an International Workshop on Data Mining Applications in Industry and Government in conjunction with PAKDD 2013, Gold Coast, Australia, April 14, 2013 http://dmapps2013.rdatamining.com To attend the workshop, you need to register for PAKDD 2013 … Continue reading →

These are some notes on my current R git work flow, which is quite fluid, and git has enough quirks that I usually forget part of it ! Creating Projects I've used both RStudio and Eclipse. RStudio seems easier to create a 'project' and add a loca...

In prior posts, I have shown how to download fantasy football projections from ESPN, CBS, and NFL.com. In this post, I will demonstrate how to take the projected points from these sources and The post Calculating Custom Fantasy Football Projections for Your League using R appeared first on Fantasy Football Analytics.

More news about MCMSki IV! Remember, the call is still open for contributed sessions for a few more weeks, till March. 20 to be precise (make sure to contact me at [email protected] if you are considering putting one session together). To all those who already submitted a session, thanks a lot, please stay tuned, and

This puzzle came up in the New York Times Number Play blog. It goes like this: An entrepreneur has devised a gambling machine that chooses two independent random variables x and y that are uniformly and independently distributed between 0 and 100. He plans to tell any customer the value of x and to ask him