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A Friday round-up

December 1, 2011
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A Friday round-up

Just a brief selection of items that caught my eye this week. Note that this is a Friday as opposed to Friday, lest you mistake this for a new, regular feature. 1. R/statistics ggbio A new Bioconductor package which builds on the excellent ggplot graphics library, for the visualization of biological data. R development master

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More Dabblings With Local Sentencing Data

December 1, 2011
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More Dabblings With Local Sentencing Data

In Accessing and Visualising Sentencing Data for Local Courts I posted a couple of quick ways in to playing with Ministry of Justice sentencing data for the period July 2010-June 2011 at the local court level. At the end of the post, I wondered about how to wrangle the data in R so that I

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quantum forest

December 1, 2011
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quantum forest

Thanks to a link on R-bloggers, I was introduced to Luis Apiolaza’s blog, Quantum Forest, which covers data analyses and R comments he encounters in his research as a quantitative forester/geneticist. And he works at the University of Canterbury, Christchurch, where I first taught from Bayesian Core in 2006. Which may be why he chose

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mean of an absolute Student’s t

November 30, 2011
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mean of an absolute Student’s t

Having (rather foolishly) involved myself into providing an answer for Cross Validated: “Can the standard deviation of non-negative data exceed the mean?“, I ended up having to derive the mean of the absolute value of a Student’s variate X.  (Well, not really, but then I did.) I think the following is correct: where is the

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Ulam Spirals in R and ggplot

November 29, 2011
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Ulam Spirals in R and ggplot

Having seen a twitter post speed by about Ulam Spirals I started to read up.  As the story goes in 1963 Stanislaw Ulam was bored at conference and started scribbling numbers in a spiral. What he discovered was a strange diaginal pattern of Prime Nu...

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Accessing and Visualising Sentencing Data for Local Courts

November 29, 2011
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Accessing and Visualising Sentencing Data for Local Courts

A recent provisional data release from the Ministry of Justice contains sentencing data from English(?) courts, at the offence level, for the period July 2010-June 2011: “Published for the first time every sentence handed down at each court in the country between July 2010 and June 2011, along with the age and ethnicity of each

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Trading Strategy Sensitivity Analysis

November 28, 2011
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Trading Strategy Sensitivity Analysis

When designing a trading strategy, I want to make sure that small changes in the strategy parameters will not transform the profitable strategy into the loosing one. I will study the strategy robustness and profitability under different parameter scenarios using a sample strategy presented by David Varadi in the Improving Trend-Following Strategies With Counter-Trend Entries

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How to speed up loops in R

November 28, 2011
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How to speed up loops in R

As with any language, there are often several ways to code up the solution to a programming problem in R. If performance of the code is important (i.e. it's something you plan to run many times, or with a lot of data), how you code the solution can often have a big impact on how fast it runs. For...

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Predicting Gender

November 28, 2011
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Predicting Gender

If there are two (can be generalized to n) classes and both follow the same distribution (but with different parameters) it is possible to predict which class an observations comes from. Here I’ll try to predict a sample’s gender based on their height. The distribution of a person’s height is more or less normal. There

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A nice short article on memory in R

November 28, 2011
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A nice short article on memory in R

There is a nice short article on memory issue in R at http://www.matthewckeller.com/html/memory.html. If you use R to process large data, you might find it helpful. It introduces: - checking how much memory an object is taking; - the memory … Continue reading →

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