## Chicago R User Group… It’s for the sexy people!

April 9, 2010
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I think we all know that Morris Day was talking about when he wrote the lyrics to “The Bird”: Yes! Hold on now, this dance ain’t for everybody. Just the sexy people. White folks, you’re much too tight. You gotta shake your head like the black folks. You might get some tonight. Look out! That’s right, he was talking about the new

## The Future of Math is Statistics

April 9, 2010
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The future of math is statistics… and the language of that future is R: I’ve often thought there was way too little “statistical intuition” in the workplace. I think Author Benjamin would agree.

## Maximum Probability of Profit

April 9, 2010
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To continue with the LSPM examples, this post shows how to optimize a Leverage Space Portfolio for the maximum probability of profit. The data and example are again taken from The Leverage Space Trading Model by Ralph Vince. These optimizaitons take ...

## GLMM using DPpackage

April 9, 2010
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I was able to fit a semi-parametric Bayesian GLMM model using DPpackage. It took me many hours to sample from the posterior distribution (DPM prior):MCMC scan 1000 of 5000 (CPU time: 18950.080 s)MCMC scan 2000 of 5000 (CPU time: 22510.100 s)M...

## Gravity Game in R

April 8, 2010
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So why should R only be used for ’serious’ stuff? No longer! I’ve written the following code in R which executes a little gravitational physics game. The goal of the game is simple. You supply a velocity and direction to a spaceship with the goal of getting the ship to the

## R: heatmaps with gplots

April 8, 2010
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I use heatmaps quite a lot for visualizing data, microarrays of course but also DNA motif enrichment, base composition and other things. I particular like the heatmap.2 function of the gplots package. It has a couple of defaults that are a little ugly ...

## R: heatmaps with gplots

April 8, 2010
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I use heatmaps quite a lot for visualizing data, microarrays of course but also DNA motif enrichment, base composition and other things. I particular like the heatmap.2 function of the gplots package. It has a couple of defaults that are a little ugly ...

## New R User Group in Dallas

April 8, 2010
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Wow, it's a big week for new R User Groups. Larry D'Agostino has started up a new R user group based in Dallas, Texas (USA). It's just getting started, and Larry posted the following request on the r-help mailing list: I would like to know if there is anyone like me interested in an R User Group in Dallas,...

## R: another nifty graph

April 8, 2010
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Make sure to click on the image to see the large version. Code for this graph: moxbuller = function(n) { u = runif(n) v = runif(n) x = cos(2*pi*u)*sqrt(-2*log(v)) y = sin(2*pi*v)*sqrt(-2*log(u)) r = list(x=x, y=y) return(r) } r = moxbuller(50000) par(bg="black") par(mar=c(0,0,0,0)) plot(r$x,r$y, pch=".", col="blue", cex=1.2)

## Video of UCLA / LA RUG talk on R and C++ integration

April 7, 2010
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Thanks to the efforts of the tireless R User Group organizers Szilard Pafka (in Los Angeles, recording the talk) and Drew Conway (in New York, converting and organising hosting), there is now a video and slide combo of my recent talk about Rcpp and R...

## Video of UCLA / LA RUG talk on R and C++ integration

April 7, 2010
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Thanks to the efforts of the tireless R User Group organizers Szilard Pafka (in Los Angeles, recording the talk) and Drew Conway (in New York, converting and organising hosting), there is now a video and slide combo of my recent talk about Rcpp and RIn...

## Video of UCLA / LA RUG talk on R and C++ integration

April 7, 2010
By

Thanks to the efforts of the tireless R User Group organizers Szilard Pafka (in Los Angeles, recording the talk) and Drew Conway (in New York, converting and organising hosting), there is now a video and slide combo of my recent talk about Rcpp and R...

## An obscure integral

April 7, 2010
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$An obscure integral$

Here is an email from Thomas I received yesterday about a computation in our book Introducing Monte Carlo Methods with R: I’m currently reading your book “Introduction to Monte Carlo Methods with R” and I quite highly appreciate your work. I’m not able to see how the integral on page 74, that describes the marginal

## Correlation scatter-plot matrix for ordered-categorical data

April 7, 2010
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When analyzing a questionnaire, one often wants to view the correlation between two or more Likert questionnaire item’s (for example: two ordered categorical vectors ranging from 1 to 5). When dealing with several such Likert variable’s, a clear presentation of all the pairwise relation’s between our variable can be achieved by inspecting the (Spearman) correlation matrix (easily achieved in R...

## Video: Seamless R Extensions using Rcpp and RInside

April 7, 2010
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Dirk Eddelbuettel presented joint work with Romain François on calling C++ from R at the LA R User Group meeting last week. Now, with thanks to Drew Conway of the NY R User Group, video of the presentation is now available. It's also embedded below -- click on it for a larger view. Dirk's slides are also available for...

## Seamless R Extensions using Rcpp and RInside

April 7, 2010
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I just added a new video to the R repository, and this one comes from the Los Angeles R Meetup. The folks in LA were fortunate enough to have Dirk Eddelbuettel—renowned R expert and StackOverflow super-user—discuss his joint work with Romain François for interfacing C++ and R code using the Rcpp package. For those

## Seamless R Extensions using Rcpp and RInside

April 7, 2010
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Dirk Eddelbuettel discusses his joint work with Romain François for interfacing C++ and R code at the Los Angeles R Users Group on March 30, 2010. Dirk provides a motivation for the Rcpp packages, as well as examples and speed benchmarks.

## Matrix determinant with the Lapack routine dspsv

April 6, 2010
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The Lapack routine dspsv solves the linear system of equations Ax=b, where A is a symmetric matrix in packed storage format. However, there appear to be no Lapack functions that compute the determinant of such a matrix. We need to compute the determinant, for instance, in order to compute the multivariate normal density function. The

## correlograms are correlicious

April 6, 2010
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In the last year or so, I’ve been experimenting with different ways of displaying correlation matrices, and have gotten very fond of color-coded correlograms. Here’s one from a paper I wrote investigating the relationship between personality and word use among bloggers (click to enlarge): The rows reflect language categories from Jamie Pennebaker’s Linguistic Inquiry and

## New version of R package futile released

April 6, 2010
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The latest version of futile was released to CRAN yesterday. This release broke out the various functions into self-contained sub-packages …Continue reading »

## Cherry Picking to Generalize ~ NASA Global Temperature Trends

April 6, 2010
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The relatively (to this decade) cool 2008 global temperatures spurred talks of a warming pause, or even global cooling. The claim usually comes from people who cherry picked either data sets and(!)/or start and end points of the global temperature trends to back up their allegation. The blogosphere already has a lot on this: Skeptical

## Le Monde rank test (corr’d)

April 6, 2010
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$Le Monde rank test (corr’d)$

Since my first representation of the rank statistic as paired was incorrect, here is the histogram produced by the simulation perm=sample(1:20) saple=sum(abs(sort(perm)-sort(perm))) when . It is obviously much closer to zero than previously. An interesting change is that the regression of the log-mean on produces > lm(log(memean)~log(enn)) Call: lm(formula = log(memean) ~ log(enn)) Coefficients: (Intercept)

## R package Blotter

April 6, 2010
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How many times have you been disappointed by nice trading system, because neither trading cost or slippage or bid/ask spread were included into back-test results? Did you find difficult to back-test a portfolio in R or many portfolios with different stocks? Blotter package is supposed to solve these problems. In really – it is complicated. I

## ProbABEL – R package for GWAS data imputation

April 6, 2010
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I've been using GenABEL for some time now for GWAS analysis using related individuals. It has an excellent set of functions for estimating a kinship matrix from a dense marker panel and then using this in a linear mixed effects model to allow for relat...

## New R User Group in Chicago

April 6, 2010
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While there's been an informal coterie of R users in the Chicago area for some time (notably the fine folks behind the successful R/Finance conferences) there hasn't been a formal R User Group. Until now, that is. JD Long has taken the plunge and announced the new Chicago R User Group on meetup.com. If you're in the Chicagoland area,...

## Visualizing Arctic Sea Ice Extent Trends

April 6, 2010
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Reader GH sent me an e-mail asking about a previous Arctic sea ice extent trend post (click). GH asked …. “Why is there such a difference between this type of representation and the chart at link ? What you’ve written … Continue reading →

## Rules of Thumb to Meet R Gurus in the Help List

April 5, 2010
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Here is my personal list of rules of thumb for people who want to meet some R gurus (quickly) in the R help mailing list ([email protected]): If you want to meet Dr Bill Venables, just say something about Type III Sum of Squares (better if you also mention the “unbeatable” SAS); If you want to

## R Tools for Dynamical Systems ~ R pplane to draw phase planes

April 5, 2010
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$R Tools for Dynamical Systems ~ R pplane to draw phase planes$

MATLAB has a nice program called pplane that draws phase planes of differential equations models. pplane on MATLAB is an elaborate program with an interactive GUI where you can just type the model to draw the phase planes. The rest you fidget by clicking (to grab the initial conditions) and it draws the dynamics automatically.