Publications by xi'an
R for dummies
I already mentioned R for dummies a while ago on the ‘Og and never got around to read it from cover to back. Now that I am reduced to a dummy state with too much free time!, I can produce a full review of the book. R for dummies was written by two Belgian statistics conultants, de Vries and Meys. It covers the basics of R in five parts: intro t...
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awalé
Following Le Monde puzzle #810, I tried to code an R program (not reproduced here) to optimise an awalé game but the recursion was too rich for R: Error: evaluation nested too deeply: infinite recursion / options(expressions=)? even with a very small number of holes and seeds in the awalé… Searching on the internet, it seems the computer sim...
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Ｒによるモンテカルロ法入門
Here is the cover of the Japanese translation of our Introducing Monte Carlo methods with R book. A few year after the French translation. It actually appeared last year in August but I was not informed of this till a few weeks ago. The publisher is Maruzen, with an associated webpage if you want to order… Unless I am confused the translators...
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Le Monde puzzle [#820]
The current puzzle is… puzzling: Given the set {1,…,N} with N<61, one iterates the following procedure: take (x,y) within the set and replace the pair with the smallest divider of x+y (bar 1). What are the values of N such that the final value in the set is 61? I find it puzzling because the way the pairs are selected impacts the final valu...
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accurate ABC: comments by Oliver Ratman [guest post]
Here are comments by Olli following my post: I think we found a general means to obtain accurate ABC in the sense of matching the posterior mean or MAP exactly, and then minimising the KL distance between the true posterior and its ABC approximation subject to this condition. The construction works on an auxiliary probability space, much like ind...
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random sudokus
In a paper arXived on Friday, Roberto Fontana relates the generation of Sudoku grids to the one of Latin squares (which is unsurprising) and to maximum cliques of a graph (more surprising). The generation of a random Latin square proceeds in three steps: generate a random Latin square L with identity permutation matrix on symbol 1 (in practice, ...
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Symmetric set differences in R
My .Rprofile contains a collection of convenience functions and function abbreviations. These are either functions I use dozens of times a day and prefer not to type in full: ## my abbreviation of head() h <- function(x, n=10) head(x, n) ## and summary() ss <- summary Or problems that I'd rather figure out once, and only once: ## e...
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Le Monde puzzle [#822]
For once Le Monde math puzzle is much more easily solved on a piece of paper than in R, even in a plane from Roma: Given a partition of the set {1,…,N} in k groups, one considers the collection of all subsets of the set {1,…,N} containing at least one element from each group. Show that the size of the collection cannot be 50. Obviously, o...
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Le Monde puzzle [#824]
A rather dull puzzle this week: Show that, for any integer y, (√3-1)2y+(√3+1)2y is an integer multiple of a power of two. I just have to apply Newton’s binomial theorem to obtain the result. What’s the point?! Filed under: Books, Kids, R Tagged: Binomial theorem, Isaac Newton, Le Monde, mathematical puzzle Related To leave a comment...
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Bayesian computational tools
I just updated my short review on Bayesian computational tools I first wrote in April for the Annual Review of Statistics and Its Applications. The coverage is quite restricted, as I took advantage of two phantom papers I had started a while ago, one with Jean-Michel Marin, on hierarchical Bayes methods and on ABC. (As stressed in the first versi...
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