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Tamino’s Method: Regional Temperatures

July 11, 2011
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Tamino’s Method: Regional Temperatures

Tamino over at  Open Mind has a new post detailing his approach for calculating temperature averages. See his post here. His method is based on the Berkeley method as he notes and he uses it primarily for calculating regional or local temperature averages. Read his post for the math details behind the approach. I got

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Now I’m R-Blogging

July 10, 2011
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Today a lot of great mails arrived at my inbox. In one of them I was reading I’ve just added your feed to the site. Where did this mail come from? The sender of the email was Tal Galili. He is a researcher in BioStatistics at the Tel Aviv University, very active around the internet.

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installing R 2.13.1 on Amazon EC2′s “Amazon Linux” AMI #rstats

July 8, 2011
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installing R 2.13.1 on Amazon EC2′s “Amazon Linux” AMI #rstats

Condensed from this post (and comments) on David Chudzicki’s blog, tweaked, and updated for R-2.13.1. Assumes you’re starting with a virgin “Amazon Linux” AMI. I picked “Basic 64-bit Amazon Linux AMI 2011.02.1 Beta” (AMI Id: ami-8e1fece7) because it was marked as free tier eligible on the “Quick Start” tab of AWS’s “Launch Instance” dialog box:

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R: calculations involving months

July 7, 2011
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R: calculations involving months

Ask anyone how much time has elapsed since September last year and they’ll probably start counting on their fingers: “October, November…” and tell you “just over 9 months.” So, when faced as I was today with a data frame (named dates) like this: How to add a 7th column, with the number of months between

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rasterVis

rasterVis

The raster package defines classes and methods for spatial raster data access and manipulation. The new rasterVis package complements raster providing a set of methods for enhanced visualization and interaction. It is now at CRAN. Several examples can ...

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New R User Group in Argentina

July 5, 2011
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A new local R user group has formed in Buenos Aires, Argentina, under the succinct name ".aR". They're currently putting together the agenda for their first meeting, and are looking for speakers with expertise in the BioConductor project and Finance. If you'd like to join the group, check out the Spanish-language website for .aR, or follow @ar_usergroup on Twitter....

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Bounded target support

July 4, 2011
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Bounded target support

Here is an interesting question from Tomàs that echoes a lot of related emails: I’m turning to you for advice. I’m facing problem  where parameter space is bounded, e.g. all parameters have to be positive. If in MCMC as proposal distribution I use normal distribution, then at some iterations I get negative proposals. So my

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Testing for valid variable names

July 3, 2011
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Testing for valid variable names

I have something a fondness for ridiculous variable names, so it’s useful to be able to check whether my latest concoction is legitimate. More so if it is automatically generated. Not having an is_valid_variable_name function is one of those odd omissions from R, and the assign function doesn’t check validity. To recap, there are a

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Topic Modeling the Sarah Palin Emails

June 27, 2011
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Topic Modeling the Sarah Palin Emails

tl;dr Browse through Sarah Palin’s emails, automagically organized by topic, here. LDA-based Email Browser Earlier this month, several thousand emails from Sarah Palin’s time as governor of Alaska were released. The emails weren’t organized in any fashion, though, so to make them easier to browse, I did some topic modeling (in particular, using latent Dirichlet

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density()

June 27, 2011
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density()

Following my earlier posts on the revision of Lack of confidence, here is an interesting outcome from the derivation of the exact marginal likelihood in the Laplace case. Computing the posterior probability of a normal model versus a Laplace model in the normal (gold) and the Laplace (chocolate) settings leads to the above histogram(s), which

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