Publications by xi'an
Reaching 1000
This is the 1000th post on the ‘Og! Here are the entries that have had above 1000 views (not viewers) so far: In{s}a(ne)!! 5,353 “simply start over and build something better” 4,345 Julien on R shortcomings 1,966 Sudoku via simulated annealing 1,762 Of black swans and bleak prospects 1,462 Do we need an integrated Bayesian/likelihood infer...
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ABC in London
After the very exciting and I think quite successful ABC in Paris meeting two years ago, Michael Stumpf from Imperial College London suggested a second edition in London along the same lines. Michael kindly associated me with the planning of this meeting. It is (logically) called ABC in London (or ABCiL) and will take place in Imperial on May 5, ...
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Le Monde puzzle [#6]
A simple challenge in Le Monde this week: find the group of four primes such that any sum of three terms in the group is prime and the overall sum is minimised. Here is a quick exploration by simulation, using the schoolmath package (with its imperfections): A=primes(start=1,end=53)[-1] lengthA=length(A) res=4*53 for (t in 1:10^4){ B=sample(A...
1136 sym R (234 sym/1 pcs) 16 img
Parallel computation [permutations]
François Perron is visiting me for two months from Montréal and, following a discussion about the parallel implementation of MCMC algorithms—to which he also contributed with Yves Atchadé in 2005—, he remarked that a deterministic choice of permutations with the maximal contrast should do better than random or even half-random permutations...
1207 sym R (1745 sym/1 pcs) 16 img
UseR! 2011 in Warwick
This year useR! conference will take place in Warwick, on August 16-18. It is being organised by the department of Statistics and funded by CRiSM and Revolution Analytics (providers of the R tee-shirt!). I wish I could attend but mid-August is usually associated with genuine (post-JSM) family vacations. Filed under: R, Statistics, University li...
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Vectorize!
Here is an email sent by one of my students a few days ago: Do you know how to integrate a function with an “if”? For instance: >X=rnorm(100) >Femp=function(x){ + return(sum(X +} >integrate(Femp,0,1)$value does not work. My reply was that the fundamental reason it does not work is that integrate (or curve for instance) computes the fu...
1021 sym R (272 sym/3 pcs) 16 img
Stochastic approximation in mixtures
On Friday, a 2008 paper on Stochastic Approximation and Newton’s Estimate of a Mixing Distribution by Ryan Martin and J.K. Ghosh was posted on arXiv. (I do not really see why it took so long to post on arXiv a 2008 Statistical Science paper but given that it is not available on project Euclid, it may be that not all papers in Statistical Scienc...
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Statistics and Computing and ABC
Statistics and Computing has received several papers on ABC and plans to make a special ABC issue out of these. All submissions prior to June 2011 that will be accepted will be published in this special issue. The special issue is identified as an article type on the on-line page. In case of questions or requests please contact the Editor Gilles ...
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snow and ssh — secure inter-machine parallelism with R
I just threw a post up on Revolutions, which got a lot longer than I planned. And got me thinking. And reading (see refs in previous post). And trying. Turns out that it was way easier than I thought! The problem:From the blog post: “ OpenSSH is now available on all platforms. A sensible solution is to have *one* cluster type ...
4026 sym R (817 sym/1 pcs)
Surprising sudoku
> printSudoku(z) +-------+-------+-------+ | 9 | | 7 5 | | 6 | | 9 | | 4 5 3 | 1 7 | 2 8 | +-------+-------+-------+ | 5 | 7 | 6 | | 1 9 | 6 8 | | | 8 | 3 | 1 | +-------+-------+-------+ | 7 2 | 5 9 | 4...
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