Blog Archives

Regression Modeling Strategies Course by Frank Harrell

February 8, 2010
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Frank Harrell is teaching his 3-session short course on regression modeling strategies using R here at Vanderbilt next month. Frank is a professor and chair of the Vanderbilt Biostatistics Department, and the author of several massively popular R libra...

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Fluctuation plot using ggplot2 in R

January 22, 2010
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Found this nice way to visually summarize contingency tables using ggplot2 in R on Hadley Wickham's ggplot2 cheat sheet. Using the same data in my previous post on making scatterplots in small multiples, I'll demonstrate how to use ggfluctuation() to m...

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GWAS Manhattan plots and QQ plots using ggplot2 in R

January 20, 2010
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Will posted earlier this week about how to produce manhattan plots of GWAS results using Stata, so I thought I'd share how I do this in R using ggplot2. First, if you've never used ggplot2, you'll need to add it to your R installation by typing: install.packages("ggplot2") Once you've done that, copy and paste this command to download the functions I wrote...

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Coming to R from SQL, Python, SAS, Matlab, or Lisp

January 18, 2010
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Head over to Revolutions Blog for a list of PDF and powerpoint resources for making the transition to R from other programming or stats languages.  All of these notes come from the New York R meetup. I enjoyed browsing the meetup's files - lots of powerpoints, PDFs, and example R data files for various topics, including several slideshows on...

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ggplot2 Tutorial: Scatterplots in a Series of Small Multiples

January 11, 2010
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It took several months after learning about ggplot2 before I gave it a try myself.  I was apprehensive about learning a new graphics system with a new set of commands.  Thing is, if you've ever used plot() in R, you already know how to use much of the functionality in ggplot2!  In this tutorial I want to show you...

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New Features in ggplot2 0.8.5

January 6, 2010
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Learning R blog details some of the new features in the latest update to ggplot2. The latest version includes functions to make it easier to change axis and legend labels, as well as a function to easily set the limits of the plot display outside the range of the data. Be sure to check back next week - I'm putting...

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Use plyr instead of _apply() in R

December 30, 2009
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I've covered plyr once before, showing you how to get means and variances for two quantitative traits across multilocus genotypes. JD Long over at Cerebral Mastication recently posted a nice screencast illustrating how plyr "just works" as an alternative to R's family of apply commands.  There's a set of R functions (apply, sapply, lapply, tapply, eapply, and rapply) that...

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Capture system commands as R objects with system(…, intern=T)

December 28, 2009
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Just discovered this very handy R command to capture the output from a system command as an R object.  I wanted to use R to read in the output from another program (PLINK) and do some processing on each output file. Of course if the files are named sequentially (plink1.out, plink2.out, plink3.out, etc.) this would be simple with a...

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Browse R Graphics with the R Graph Gallery and the R Graphical Manual

December 15, 2009
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One of R's biggest strengths is its unparalleled graphing capabilities.  Just see any of our previous posts on ggplot2, visualization, or other posts tagged with R. R has several fundamentally different systems for plotting, including base graphics, lattice, and ggplot2.  Furthermore, many add-on packages come with their own functions for producing problem-domain specific graphics. For example,

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Get Started with Machine Learning in R

December 1, 2009
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A Beautiful WWW put together a great set of resources for getting started with machine learning in R.  First, they recommend the previously mentioned free book, The Elements of Statistical Learning.  Then there's a link to a list of dozens of machine learning and statistical learning packages for R.  Next, you'll need data.  Hundreds of free real datasets are...

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