September 2010

Mandelbrot Set, evolved

September 30, 2010 | David Smith

The Mandelbrot Set is perhaps the most famous fractal of all time. It's simple in its definition: iterate the complex equation zn+1 = zn2 + c (starting with z0 = 0) for various values of c, and if doesn't go to infinity then c is part of the Mandelbrot Set. The result, however, is ... [Read more...]

Plotting Time Series data using ggplot2

September 30, 2010 | Ralph

There are various ways to plot data that is represented by a time series in R. The ggplot2 package has scales that can handle dates reasonably easily. Fast Tube by Casper As an example consider a data set on the number of views of the you tube channel ramstatvid. A ...
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Moshtemp 5.1

September 29, 2010 | Steven Mosher

Time for another dump of the entire package. Get the zip file 5.1 in the box to the right. ( shortly). unzip and run the following files if you havent already: 1. downloadall.R 2. setup.R If you are running for the first time, You’ll note I added diagnostics. Sometimes the files ... [Read more...]

Le Monde puzzle [38]

September 29, 2010 | xi'an

Since I have resumed my R class, I will restart my resolution of Le Monde mathematical puzzles…as they make good exercises for the class. The puzzle this week is not that exciting: Find the four non-zero different digits a,b,c,d such that abcd is equal to the ... [Read more...]

NewTwitter design based on a Golden Spiral

September 29, 2010 | David Smith

I finally got the new version of Twitter yesterday, and it looks great. And that's no accident: according to the designer, the layout of the new Twitter interface is based on the Golden Spiral: You can describe the Golden Spiral by laying consecutive squares in a spiral fashion, each square ... [Read more...]

Cooling stations. A UHI Hint

September 29, 2010 | Steven Mosher

Update: google earth files in the box: Personally I like to look at things backwards. Why are cool sites cool? So download the kml or kmz file and you can tour 62 sites: All with 90 years of data or more. All with a cooling trend. And all “supposedly” urban. what do ...
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Some Oddities with cooling stations

September 29, 2010 | Steven Mosher

Now, that  the whole analysis has been moved to raster, I took some time to play around with a question that has interested  a couple of people. Cool stations. A while back when I was looking at ways of bounding uncertainties in the record I went on a hunt for ...
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A texteditor for R

September 29, 2010 | Rob J Hyndman

I’ve been using RWinEdt for the last few years for all my R coding. But it no longer works with WinEdt 6.0 and no update has been forthcoming. Consequently, I’ve been looking around for something similar to take its place. This question has been asked before on StackOverflow and ...
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Forecasting with long seasonal periods

September 28, 2010 | Rob J Hyndman

I am often asked how to fit an ARIMA or ETS model with data having a long seasonal period such as 365 for daily data or 48 for half-hourly data. Generally, seasonal versions of ARIMA and ETS models are designed for shorter periods such as 12 for monthly data or 4 for quarterly data. ... [Read more...]

Google Summer of Code advances R

September 28, 2010 | David Smith

For the third year running, the Google Summer of Code program has sponsored a number of students working with R, and has again resulted in several new contributions expanding R in various fields. Dirk Eddelbuettel, who coordinated the R-related projects for GSoC in 2010, summarized the results, with details about the ... [Read more...]

A Slider to Control Two Plotting Windows

September 28, 2010 | Yihui Xie

One of my readers asked two weeks ago how to control two graphics windows with the slider in gWidgets. Here is a simple example: if (!require("gWidgetsRGtk2")) install.packages("gWidgetsRGtk2") library(gWidgetsRGtk2) options(guiToolkit = "RGtk2") graphics.off() x11() x11() dev.set() gslider(from = 1, to = 100, value = 10,     container = gwindow("Two Plotting Windows"), ... [Read more...]

What is wrong with this graph?

September 28, 2010 | Social data blog

This is a graph from our surveys with the University of Munich in B&H about ten years ago.(Click on it to see a large version.) In previous presentations (but not in peer-reviewed journals) I have talked about the peak on the subscale ...
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Galton & simulation

September 27, 2010 | xi'an

Stephen Stigler has written a paper in the Journal of the Royal Statistical Society Series A on Francis Galton’s analysis of (his cousin) Charles Darwin’ Origin of Species, leading to nothing less than Bayesian analysis and accept-reject algorithms! “On September 10th, 1885, Francis Galton ushered in a new era of ... [Read more...]

Mean reverting strategies and volatility

September 27, 2010 | kafka

Mean reverting strategies are beating on mean reversion of the prices. There are various flavors of mean reverting strategies, but as a proxy I chose RSI(2). You can find many entries on blogosphere about this strategy, but nowadays its popularity dried up. What made me wondering is that there was ...
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