Monthly Archives: June 2010

Learning R

June 17, 2010
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When R is brought up as a possibility for doing statistics or data mining or any sort of predictive analytics among non R users, someone will invariably point out that R has a “steep learning curve”, and the response among those gathered usually includes a significant amount of head nodding. Even those who have put in heroic efforts to...

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Comparing standard R with Revoutions for performance

June 17, 2010
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Comparing standard R with Revoutions for performance

Following on from my previous post about improving performance of R by linking with optimized linear algebra libraries, I thought it would be useful to try out the five benchmarks Revolutions Analytics have on their Revolutionary Performance pages.

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Comparing standard R with Revoutions for performance

June 17, 2010
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Comparing standard R with Revoutions for performance

Following on from my previous post about improving performance of R by linking with optimized linear algebra libraries, I thought it would be useful to try out the five benchmarks Revolutions Analytics have on their Revolutionary Performance pages.

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Shrinking R’s PDF output

June 17, 2010
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R is great for graphics, but I've found that the PDF's R produces when drawing large plots can be extremely large. This is especially common when using spplot() to plot a large raster. I've made a 15 page PDF full of rasters that was hundreds of MB in size.  Obviously I don't need all the detail (every pixel of...

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Calling Ruby, Perl or Python from R

June 16, 2010
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Calling Ruby, Perl or Python from R

If you want to interact with other programming languages from R, there are various packages and bindings available. These packages provide a pretty high degree of integration between the langages and allow you to pass objects back and forth seemlessl...

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Conferenza a Padova

June 16, 2010
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Conferenza a Padova

Today and tomorrow, I am attending the annual Italian statistical society meeting. While I appreciate very much the invitation, as well as the opportunity to walk through  Padova and Venezia for a short (and alas rainy!) hour on the way there (leaving home at 8am, walking in Venezia at noon!), I am rather skeptical of

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Mary, Chloe, and Miriam at breakfast

June 16, 2010
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Mary, Chloe, and Miriam at breakfast

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R-help follow-up: truncated exponential

June 16, 2010
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R-help follow-up: truncated exponential

I recently posted the message below with regard to sampling from the truncated exponential distribution. I left out the derivation of the CDF (mostly because text math is ugly), so I’ve included it here. There is also a short JSS article about truncated distributions in R. This problem in particular may likely be found in

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R Sapply Problem

Any expert in R please educates me. I have got a problem about the sapply (or lapply), it made me headache for over two hours.As "for loop" is very slow in R, we should try best to avoid using it, and to use vectorization instead. sapply is designed for this, for example, instead of:for (i in 1:10) {z <-...

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R Commander – hypothesis testing

June 16, 2010
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R Commander – hypothesis testing

The R Commander GUI can be used to perform classical hypothesis testing. There are menu options to undertake the variants on the t-test as well as tests on proportions or equality of variances for two samples of data. Fast Tube by Casper The “Statistics” menu provides access to various hypothesis tests via the “Means” sub-menu including: Single sample

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