Monthly Archives: June 2012

Quasi-Random Number Generation in R

Random number generation is a core topic in numerical computer science. There are many efficient algorithms for generating random (strictly speaking, pseudo-random) variates from different probability distributions. The figure below shows a sampling of 1000 two-dimensional random variates from the … Continue reading →

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F-test to find UECLs

June 5, 2012
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F-test to find UECLs

I have fixed the link to the video "Removing Y outliers from the validation set" and it´s time to see what could be the next step to the function. As we know the RMSEP is the sum of the explained (BIAS) and unexplained error (SEP). We get also the SEP...

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Example 9.34: Bland-Altman type plot

June 5, 2012
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Example 9.34: Bland-Altman type plot

The Bland-Altman plot is a visual aid for assessing differences between two ways of measuring something. For example, one might compare two scales this way, or two devices for measuring particulate matter. The plot simply displays the difference between the measures against their average. Rather than a statistical test, it is intended...

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NBA Playoff Predictions Update 3 (4-2)

June 5, 2012
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NBA Playoff Predictions Update 3 (4-2)

This is my third update to my original post on predicting the NBA playoffs with an algorithm. Here are updates 1 and 2. The algorithm correctly predicted a Boston win, but missed on the Spurs/Thunder game, so it is currently 4-2. Haven't had any time...

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Digitize linear and (semi-)log scale graphs with multiple point sets

June 5, 2012
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Digitize linear and (semi-)log scale graphs with multiple point sets

Working on a paper, I ran into the problem of needing data from a graph that was not mine, and for which no underlying table was published. With today's software packages, it is however not very difficult to digitize a figure yourself. I remembered rea...

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Announcing Revolution R Enterprise 6.0

June 5, 2012
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Revolution Analytics is proud to announce the latest update to our enhanced, production-grade distribution of R, Revolution R Enterprise. This update expands the range of supported computation platforms, adds new Big Data predictive models, and updates to the latest stable release of open source R (2.14.2), which improves performance of the R interpreter by about 30%. This release expands...

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Book Review: Parallel R

June 5, 2012
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Book Review: Parallel R

You have a problem: R is single-threaded, but your code would be faster if it could simultaneously run on more than one core.  You have access to a cluster and/or your computer has multiple cores.  Parallel R, by Q. Ethan McCallum and Stephen...

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intersect for multiple vectors in R

June 5, 2012
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Say you havea <- c(1,3,5,7,9)b <- c(3,6,8,9,10)c <- c(2,3,4,5,7,9)A straightforward way to do the job is:intersect(intersect(a,b),c)More cleverly, and more conveniently if you have a lot of arguments:Reduce(intersect, list(a,b,c))The Reduce fu...

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NBA Playoff Predictions Update 3 (4-2)

June 5, 2012
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NBA Playoff Predictions Update 3 (4-2)

This is my third update to my original post on predicting the NBA playoffs with an algorithm. Here are updates 1 and 2. The algorithm correctly predicted a Boston win, but missed on the Spurs/Thunder game, so it is currently 4-2. Haven't had any time ...

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UK house prices visualised with googleVis-0.2.16

June 5, 2012
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UK house prices visualised with googleVis-0.2.16

A new version of googleVis has been released on CRAN and the project site. Version 0.2.16 adds the functionality to plot quarterly and monthly data as a motion chart. To illustrate the new feature I looked for a quarterly data set and stumbled across t...

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