R Graphics

Graphically analyzing variable interactions in R

August 23, 2011 |

I studied Ecology as an undergraduate, which meant I spent a lot of time gathering and analyzing field data. One of the basic tools we used to look for relationships in a large set of variables was correlation and scatterplot matrices. Each of these ... [Read more...]

Produce Authentic Math Formulas in R Graphics

April 30, 2011 |

I remember a few weeks ago, there was a challenge in the R-help list to make the prime symbol in R graphics. In LaTeX, we simply write $X'$ or $X^\prime$. R has a rough support for math expressions (see demo(plotmath)) and they are certainly unsatisfactory for LaTeX users. ... [Read more...]

Review of “R Graphs Cookbook” by Hrishi Mittal

January 24, 2011 |

Executive summary: Extremely useful for new users, informative to even quite seasoned users. Refereeing Once upon a time a publisher asked if I would referee a book (unspecified) about R.  In an instance that can only be described as psychotic I said yes.  That bit of insanity turned out to ...

A Special Graphics Device in R: the Null Device

December 22, 2010 |

It is well-known that R has several graphics devices — either the screen devices (X11(), windows(), …) or the off-screen devices (pdf(), png(), …). We can query the default graphics device in options(): getOption('device') In a non-interactive session, the default device is pdf(). This is why Sweave has to create a file ... [Read more...]

alphahull: an R Package for Alpha-Convex Hull

April 16, 2010 |

new paper on the α-convex hull appeared in the Journal of Statistical Software today (http://www.jstatsoft.org/v34/i05/paper). The α-convex hull is an interesting problem which caught my attention long time ago but I didn’t know a solution then. R has a function chull() which can ... [Read more...]

Demonstrating the Power of F Test with gWidgets

April 2, 2010 |

e know the real distribution of the F statistic in linear models — it is a non-central F distribution. Under H0, we have a central F distribution. Given 1 – α, we can compute the probability of (correctly) rejecting H0. I created a simple demo to illustrate how the power changes as other parameters ... [Read more...]

A Demo for the Ratio Estimation in Sampling Survey (Animation)

March 24, 2010 |

mber Watkins gave me a suggestion on the animation for the ratio estimation, and I think this is a good topic for my animation package. I’ve finished writing the initial version of the function sample.ratio() for this package, which will appear in the version 1.1-2 a couple of ... [Read more...]

Font Families for the R PDF Device

March 24, 2010 |

otivated by the excellent R package pgfSweave, I begin to notice the font families in my graphs when writing Sweave documents. The default font family for PDF graphs is Helvetica, which is, in most cases (I think), inconsistent with the LaTeX font styles. Some common font families are listed in ?... [Read more...]

R Tips in Stat 511

March 22, 2010 |

Here are some (trivial) R tips in the course Stat 511. I’ll update this post till the semester is over. Formatting R Code Reading code is pain, but the well-formatted code might alleviate the pain a little bit. The function tidy.source() in the animation package can help us format ... [Read more...]

Happy New Year with R

December 31, 2009 |

I have to admit that the previous post on Christmas is actually not much fun. Today I received another pResent from Yixuan which is more interesting: Basically the code deals with letter polygons (i.e. glyphs) and plot them with proper projections from 3D to 2D space: ## original code by ... [Read more...]

Create Animations in PDF Documents Using R

November 11, 2009 |

ince animation 1.0-9, we will be able to create a PDF document with an animation embedded in it; the function is saveLatex(), and its usage is similar to saveMovie() and saveSWF(): you pass an R expression for creating animations to this function, and this expression will be evaluated in the ... [Read more...]

50000 Revisions Committed to R

October 10, 2009 |

oday Romain Francois posted an interesting topic in the R-help list, and you can read his blog post for more details: celebrating R commit #50000. 50000 is certainly not a small number; we do owe R core members a big “thank you” for their great efforts in this fantastic statistical language in ... [Read more...]

Simulation of Burning Fire in R

June 11, 2009 |

inlin Yan posted a cool (hot?) simulation of burning fire with R in the COS forum yesterday, which was indeed a warm welcome. I’m not sure whether our forum members will be scared by the “fire” under the title “Welcome to COS Forum”. The fire was mainly created by ... [Read more...]

Identify Data Points in Off-Screen R Graphics Devices

March 16, 2009 |

Today Ruya Gokhan Kocer asked me how to use the R function identify() in off-screen graphics devices. Actually it’s pretty easy as long as we obtain the list returned by identify(pos = TRUE). For example, # open a windows device x11() x = rnorm(20) y = rnorm(20) plot(x, y) # identify 5 points ... [Read more...]

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