Blog Archives

Graph-based circle packing

July 27, 2015
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Graph-based circle packing

The previous two posts showed examples of a simple circle packing algorithm using the packcircles package (available from CRAN and GitHub). The algorithm involved iterative pair-repulsion to jiggle the circles until (hopefully) a non-overlapping arrangement emerged. In this post we'll look an alternative approach. An algorithm to find an arrangement of circles satisfying a prior specification of...

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Static and moving circles

May 29, 2015
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Static and moving circles

After the previous post on the packcircles package for R someone suggested it would be useful to be able to fix the position of selected circles. As a first attempt, I've added an optional weights argument to the circleLayout function. Weights can be in the range 0-1 inclusive, where a weight of 0 prevents a circle from moving,...

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Circle packing in R (again)

April 29, 2015
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Circle packing in R (again)

Back in 2010 I posted some R code for circle packing. Now, just five years later, I've ported the code to Rcpp and created a little package which you can find at GitHub.The main function is circleLayout which takes a set of overlapping circles and tries to find a non-overlapping arrangement for them. Here's an example:

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Fitting an ellipse to point data

September 30, 2012
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Fitting an ellipse to point data

Some time ago I wrote an R function to fit an ellipse to point data, using an algorithm developed by Radim Halíř and Jan Flusser1 in Matlab, and posted it to the r-help list. The implementation was a bit hacky, returning odd results for some data. A couple of days ago, an...

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Monte Carlo testing of classification groups

September 1, 2010
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Monte Carlo testing of classification groups

This is another article on the theme of defining groups in a hierarchical classification. A previous article described homogeneity analysis to visualize how any well any number of groups, defined at the same level accounts for the variability in the da...

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Fun with the proto package: building an MCMC sampler for Bayesian regression

August 12, 2010
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Fun with the proto package: building an MCMC sampler for Bayesian regression

The proto package is my latest favourite R goodie. It brings prototype-based programming to the R language - a style of programming that lets you do many of the things you can do with classes, but with a lot less up-front work. Louis Kates and Thomas P...

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Homogeneity analysis of hierarchical classifications

August 10, 2010
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Homogeneity analysis of hierarchical classifications

I've spent more years than I care to remember analysing vegetation survey data (typically species abundances in plots) using a variety of software including my own algorithms coded in FORTRAN and C++. A recent query on the r-help list, about how to det...

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Meeting in the middle; or fudging model II regression with nls

August 3, 2010
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Meeting in the middle; or fudging model II regression with nls

My colleague Karen needed an equation to predict trunk diameter given tree height, which she hoped to base on measurements of trees in semi-arid Australian woodlands. This is the dark art of allometry and a quick google found a large number of formulae...

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Circle packing with R

July 26, 2010
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Circle packing with R

To visualize the results of a simulation model of woodland trees within R, I needed an algorithm that could arrange a large number of circles within a rectangle such that no two circles overlapped by more than a specified amount. A colleague had approa...

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