Monthly Archives: September 2010

Rllvm

September 1, 2010
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Rllvm

Over the past 10 years, I have been torn between building a new stat. computing environment or trying to overhaul R. There are many issues on both sides. But the key thing is to enable doing new and better things in stat. computing rather than just making the existing things easier and more user-friendly. If

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Rffi

September 1, 2010
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Rffi

A few weeks ago, I posted the Rffi package on the Omegahat repository. It is an interface to libffi which is a portable mechanism for invoking native routines without having to write and compile any wrapper routines in the native language. In other words, we can use this in R to call C routines using

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How to generate correlated random numbers

September 1, 2010
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We've covered how to generate random numbers in R before, but what if you want to go beyond generating one random number at a time? What if you want to generate two, or three or more random numbers, and what's more, you want them to be correlated? JD Long lays out the way in a couple of posts at...

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Random dive MH

September 1, 2010
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Random dive MH

A new Metropolis-Hastings algorithm that I would call “universal” was posted by Somak Dutta yesterday on arXiv. Multiplicative random walk Metropolis-Hastings on the real line contains a different Metropolis-Hastings algorithm called the random dive. The proposed new value x’ given the current value x is defined by when is a random variable on . Thus,

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How to check if a file exists with HTTP and R

September 1, 2010
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How to check if a file exists with HTTP and R

So, there’s probably an easier way to do this (please let me know if you know it)… Suppose you’re working with a system which creates (binary) files and posts them for download on a website. You know the names of the files that will be created. However, they may not have been made yet (they’re

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Is this good or bad programming?

September 1, 2010
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If I come across this kind of code when I'm checking (QCing) code it makes me want to punch the programmer's face. I find that it's impossible to step through and check each dataset with the previous incarnation. Which is how I check what h...

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apply() function and ABM in R

September 1, 2010
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I know know...I've been away again...We (myself and Mark Lake) are presenting a paper at the CECD conference and we have still some to stuff to finish...so I'm really, really busy... I'll post asap a much more detailed post on the conference and o...

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apply() function and ABM in R

September 1, 2010
By

I know know...I've been away again...We (myself and Mark Lake) are presenting a paper at the CECD conference and we have still some to stuff to finish...so I'm really, really busy... I'll post asap a much more detailed post on the conference and o...

Read more »

Monte Carlo testing of classification groups

September 1, 2010
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This is another article on the theme of defining groups in a hierarchical classification. A previous article described homogeneity analysis to visualize how any well any number of groups, defined at the same level accounts for the variability in the dataset, as measured by within-group pairwise distances. Here we will look at testing whether splitting a particular group...

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Monte Carlo testing of classification groups

September 1, 2010
By
Monte Carlo testing of classification groups

This is another article on the theme of defining groups in a hierarchical classification. A previous article described homogeneity analysis to visualize how any well any number of groups, defined at the same level accounts for the variability in the da...

Read more »