[R] Summer student internship placement at University of York / YCCSA / SEI (paid)
Dear R-lings, I did not know which list to post to, because it is a studentship so not really a job, so it did not fit the r-sig-jobs list and it is about devloping an extension package interfaced with R I hope I did not upset anyone. If so apologies. The Centre For Complex systems Analysis at the University of York (YCCSA) in UK in collaboration with Stockholm Environment Institute is looking for a highly motivated student in Computer Science, Applied Mathematics, Applied Statistics or related fields for a 10 weeks paid student internship over the summer 2011, starting in july, to collaborate in development of a R package. The student will participate in research projects to develop prototypes for toolkits for statistical predictions of diversity and dissimilarity and the generation of spatial landscapes, with applications in the biological and environmental sciences. We require excellent development skills and experience in CUDA/openCL, and a strong foundation in Computing, Statistics / Applied Mathematics and COmputer Graphics. We need an excellent problem solver, able to innovate, find solutions and work independently. For further information on the project please contact ct...@york.ac.uk or go to http://www.york.ac.u...2011/201107.pdf For further information on the studentship programme please look at http://www.york.ac.u...olarships.html. Please send your application not later than the 13 of may to scholarsh...@yccsa.org as one single pdf document including: 1. Your CV (max 2 pages) 2. A brief personal statement (max 1 page) including: * Which project(s) you are interested in (as many as you like but in preference order) * Your reasons for applying * Your academic interest * Your future aspirations 3. A full written academic reference (not just contact details). Your application will not be accepted without this reference (max 1 page). Best, -- Corrado Topi Stockholm Environment Institute Mob: +44 (0) 7769 601784 Tel: +44 (0) 1904 322893 Skype: corrado-eeos Website: sei-international.org University of York York YO10 5DD UK Fax: +44 (0) 1904 322898 EMAIL DISCLAIMER: http://www.york.ac.uk/docs/disclaimer/email.htm -- Corrado Topi Stockholm Environment Institute Mob: +44 (0) 7769 601784 Tel: +44 (0) 1904 322893 Skype: corrado-eeos Website: sei-international.org University of York York YO10 5DD UK Fax: +44 (0) 1904 322898 EMAIL DISCLAIMER: http://www.york.ac.uk/docs/disclaimer/email.htm __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Concave hull
Dear David and other concave-hull-ists, yes, I meant concave hulls indeed. I know about the algorithm mentioed (www.concavehull.com) but it is not open source, so you cannot integrate it in R, and it is apparently patented, so even if you find the description you cannot apply it to implement a solution (even if patenting algorithms is at least questionable and has a rather patchy validity). Some questions / comments which applies to David's approach but in general even to convex hulls (question 2): 1) How do you extend it to n dimensions (in R)? 2) How do you do set calculus (horrible expression to mean: union, intersection, difference, and particularly membership, and so on ) on these hulls (in R)? Finally, I am at the moment using a gis to do it, but I did not find any command for concave hulls in grass. There is a rather long a convoluted way of doing them, but nearly impossible to automatise (see http://grass.osgeo.org/wiki/Create_concave_hull). Looking for the capability of extending it to the n-dimensional case does not sound right, because gis is thought for working in 2d/3d. Best, On Nov 26 2009, David Winsemius wrote: On Nov 25, 2009, at 7:51 PM, David Winsemius wrote: Drats; Forgot the plot: xx - runif(100, -1, 1) yy - abs(xx)+rnorm(100,0,.2); plot(xx,yy, xlim=c( min(xx)-sd(xx), max(xx)+sd(xx)), ylim =c( min(yy)-sd(yy), max(yy)+sd(yy))) dens2 - kde2d(xx, yy, lims=c(min(xx)-sd(xx), max(xx)+sd(xx), min(yy)-sd(yy), max(yy)+sd(yy) ) ) contour(dens2, add=TRUE) # You can pick a single contour if you like: contour(dens2, level=0.05, col=red, add=TRUE) contour(dens2, level=0.10, col=blue, add=TRUE) And as a further note you can drop the bandwidth and lower the density level to get a tighter fit: xx - runif(1, -1, 1) yy - abs(xx)+rnorm(1 ,0,.2); plot(xx,yy, xlim=c( min(xx)- sd(xx), max(xx)+sd(xx)), ylim =c( min(yy)-sd(yy), max(yy)+sd(yy)), cex=.2) dens2 - kde2d(xx, yy, lims=c(min(xx)-sd(xx), max(xx)+sd(xx), min(yy)- sd(yy), max(yy)+sd(yy) ) , h=c(bandwidth.nrd(xx)/4, bandwidth.nrd(xx)/ 4) ) contour(dens2, add=TRUE) # You can pick a single contour if you like: contour(dens2, level=0.05, col=red, add=TRUE) contour(dens2, level=0.10, col=blue, add=TRUE) contour(dens2, level=0.005, col=red, add=TRUE) (More bat-like.) -- Corrado Topi Global Climate Change Biodiversity Indicators Area 18,Department of Biology University of York, York, YO10 5YW, UK Phone: + 44 (0) 1904 328645, E-mail: ct...@york.ac.uk __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
