Bot Botany – K-Means and ggplot2

September 2, 2010
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Bot Botany – K-Means and ggplot2

So if you had a robot that was an expert at botany - would you have a bot botanist?  Among other things, it would need to to distinguish flowers through vision and image processing, and be able to classify various kinds of plants based upon specif...

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Bot Botany – K-Means and ggplot2

September 2, 2010
By
Bot Botany – K-Means and ggplot2

So if you had a robot that was an expert at botany - would you have a bot botanist?  Among other things, it would need to to distinguish flowers through vision and image processing, and be able to classify various kinds of plants based upon specif...

Read more »

New R User Group in New Jersey

September 2, 2010
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Folks in the New Jersey area no longer need to trek over to New York City to meet other R users. Now there's NewJerseyR, a new R user group put together by Mango Solutions. The first meeting will in Iselin on September 16, with speakers from Mango, Pfizer, and Bristol Myers Squibb. Full details at the NewJerseyR website, linked...

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Statisfaction

September 2, 2010
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Statisfaction

A collective blog has been started by the statistics students and postdocs at CREST, in the wake of the Valencia meeting. It is called Statisfaction. (The Rolling Stones of Statistics?! Actually, Andrew Gelman also has a post with that title… And it is even part of the Urban Dictionnary!) Since I have no responsability nor

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Update

September 2, 2010
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Update

I tried using my own little palette with more traditional looking heatmap colors (red and pink are the densest, blue and green are less so, yellow in the middle, etc.). I also included the actual points, but would recommend it for more than a single g...

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How the expiration of the assault weapon ban affected Mexico

September 2, 2010
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How the expiration of the assault weapon ban affected Mexico

There has been a lot of attention paid to the role of US guns exacerbating the violence in Mexico. The assault-weapon ban expired on September 14, 2004, but with the recent spiraling of violence in Mexico the ban has attracted renewed attention. Just recently the Mexican President stood before the American Congress and blamed the assault weapon...

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How the expiration of the assault weapon ban affected Mexico

September 2, 2010
By
How the expiration of the assault weapon ban affected Mexico

There has been a lot of attention paid to the role of US guns exacerbating the violence in Mexico. The assault-weapon ban expired on September 14, 2004, but with the recent spiraling of violence in Mexico the ban has attracted renewed attention. Just recently the Mexican President stood before the American Congress and blamed the assault weapon...

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R-bloggers announcement – maintenance mode – site might be down

September 2, 2010
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Hello dear followers of R-bloggers.com Today (and probably in the next few days), R-bloggers will be down part of the time due to maintenance work. (Technical stuff: I am moving the site from shared hosting to VPS, and there seem to be a few bumps in the road) Sorry for the inconvenience, I will update once it would look...

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Third, and Hopefully Final, Post on Correlated Random Normal Generation (Cholesky Edition)

September 2, 2010
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Third, and Hopefully Final, Post on Correlated Random Normal Generation (Cholesky Edition)

When I did a brief post three days ago I had no plans on writing two more posts on correlated random number generation. But I’ve gotten a couple of emails, a few comments, and some Twitter feedback. In response to my first post, Gappy, calls me out and says, “the way mensches do multivariate (log)normal

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Stochastic approximation in Bristol

September 2, 2010
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Stochastic approximation in Bristol

This is very short notice, but for those in the vicinity and not at the RSS conference, there is a highly interesting workshop taking place in Bristol in ten days (I would certainly have gone, had I not been at the same time in Banff!): We would like to invite you to contribute to our

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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
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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...

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Using XML package vs. BeautifulSoup

August 31, 2010
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Using XML package vs. BeautifulSoup

A while back I posted something about scraping a webpage using the BeautifulSoup module in Python.  One of the comments to that post was by Larry — a blogger over at IEORTools — suggesting that I take a look at … Continue reading →

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Better than Average

August 31, 2010
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Better than Average

The NIST's The Engineering Statistics Handbook includes an Introduction to Time Series Analysis which provides a great way of demonstrating how R can be used to make such calculations.  This post replicates the analys...

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Better than Average

August 31, 2010
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Better than Average

The NIST's The Engineering Statistics Handbook includes an Introduction to Time Series Analysis which provides a great way of demonstrating how R can be used to make such calculations.  This post replicates the analys...

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apply functions in R

August 31, 2010
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Getting to know the "apply"s in R is extremely handy for using the language efficiently and effectively. Unfortunately, the help files tend to be rather information-dense and are fairly overwhelming for newcomers. A recent blog post by Neil Saunders pr...

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apply functions in R

August 31, 2010
By

Getting to know the "apply"s in R is extremely handy for using the language efficiently and effectively. Unfortunately, the help files tend to be rather information-dense and are fairly overwhelming for newcomers. A recent blog post by Neil Saunders pr...

Read more »

Birds of a feather shop together

August 31, 2010
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Birds of a feather shop together

PREDICTING CONSUMER BEHAVIOR FROM SOCIAL NETWORKS This week, Decision Science News is doing a special cross-posting with Messy Matters. The post below is by Sharad Goel and describes work that he and your Decision Science News editor Dan Goldstein are jointly undertaking at Yahoo! Do you know what the #$*! your social media strategy is?

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R is indispensable, because it’s reproducible

August 31, 2010
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Maria Wolters, self-styled "Science-Mum of two" and speech and language technology researcher, has a great blog post about the one tool she couldn't live without: R. Maria says R is her "favourite tool for analysing experimental results and modelling the resulting patterns of behaviour and preferences", and explains why: R is a programming language for everything statistical. It’s free,...

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Soil Properties Visualized on a 1km Grid

August 31, 2010
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Soil Properties Visualized on a 1km Grid

Fresno Area Urban Areas vs Irrigated LCC: grey regions are current urban areas A couple of maps generated from a 1km gridded soil property database, derived from SSURGO data where available with holes filled with STATSGO data. Soil properties visualize...

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Namespaces and name conflicts

August 31, 2010
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Namespaces and name conflicts

R packages ‘igraph’ and ‘network’ are good examples of two R packages providing similar but complementary functionalities for which there are a lot of name conflicts. As for now the ‘igraph’ package has a namespace while the ‘network’ package (version 1.4-1) does not. This became an issue when I was working on the ‘intergraph‘ package.

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