Blog Archives

Generation of E-Learning Exams in R for Moodle, OLAT, etc.

December 20, 2012
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Generation of E-Learning Exams in R for Moodle, OLAT, etc.

(Guest post by Achim Zeileis) Development of the R package exams for automatic generation of (statistical) exams in R started in 2006 and version 1 was published in JSS by Gr?n and Zeileis (2009). It was based on standalone Sweave exercises, that can be combined …Read more »

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Comparing Shiny with gWidgetsWWW2.rapache

November 12, 2012
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(A guest post by John Verzani) A few days back the RStudio blog announced Shiny, a new product for easily creating interactive web applications (http://www.rstudio.com/shiny/). I wanted to compare this new framework to one I’ve worked on, gWidgetsWWW2.rapache – a version of …Read more »

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How to load the {rJava} package after the error “JAVA_HOME cannot be determined from the Registry”

August 7, 2012
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In case you tried loading a package that depends on the {rJava} package (by Simon Urbanek), you might came across the following error: Loading required package: rJava library(rJava) Error : .onLoad failed in loadNamespace() for ‘rJava’, details: call: fun(libname, pkgname) …Read more »

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data.table version 1.8.1 – now allowed numeric columns and big-number (via bit64) in keys!

May 9, 2012
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This is a guest post written by Branson Owen, an enthusiastic R and data.table user. Wow, a long time desired feature of data.table finally came true in version 1.8.1! data.table now allowed numeric columns and big number (via bit64) in …Read more »

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Speed up your R code using a just-in-time (JIT) compiler

April 10, 2012
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This post is about speeding up your R code using the JIT (just in time) compilation capabilities offered by the new (well, now a year old) {compiler} package. Specifically, dealing with the practical difference between enableJIT and the cmpfun functions. …Read more »

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Do more with dates and times in R with lubridate 1.1.0

March 16, 2012
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This is a guest post by Garrett Grolemund (mentored by Hadley Wickham) Lubridate is an R package that makes it easier to work with dates and times. The newest release of lubridate (v 1.1.0) comes with even more tools and …Read more »

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Printing nested tables in R – bridging between the {reshape} and {tables} packages

January 29, 2012
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Printing nested tables in R – bridging between the {reshape} and {tables} packages

This post shows how to print a prettier nested pivot table, created using the {reshape} package (similar to what you would get with Microsoft Excel), so you could print it either in the R terminal or as a LaTeX table. This task is done by bridging between the cast_df object produced by the {reshape} package,

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Interactive Graphics with the iplots Package (from “R in Action”)

January 24, 2012
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Interactive Graphics with the iplots Package (from “R in Action”)

(This article was first published on R-statistics blog » R, and kindly contributed to R-bloggers) The followings introductory post is intended for new users of R.  It deals with interactive visualization using R through the iplots package. This is a guest article by Dr. Robert I. Kabacoff, the founder of (one of) the first online R tutorials websites: Quick-R. Kabacoff has...

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Merging two data.frame objects while preserving the rows’ order

January 15, 2012
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Merging two data.frame objects while preserving the rows’ order

Merging two data.frame objects in R is very easily done by using the merge function. While being very powerful, the merge function does not (as of yet) offer to return a merged data.frame that preserved the original order of, one of the two merged, data.frame objects. In this post I describe this problem, and offer Read more...

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Aggregation and Restructuring data (from “R in Action”)

January 9, 2012
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Aggregation and Restructuring data (from “R in Action”)

The followings introductory post is intended for new users of R.  It deals with the restructuring of data: what it is and how to perform it using base R functions and the {reshape} package. This is a guest article by Dr. Robert I. Kabacoff, the founder of (one of) the first online R tutorials websites: Quick-R. Kabacoff Read more...

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