Monthly Archives: April 2010

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...

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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 RIn...

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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...

Read more »

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

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Correlation scatter-plot matrix for ordered-categorical data

April 7, 2010
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Correlation scatter-plot matrix for ordered-categorical data

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...

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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...

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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

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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.

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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

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correlograms are correlicious

April 6, 2010
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correlograms are correlicious

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

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