Posts Tagged ‘ puzzle ’

Code Optimization: One R Problem, Ten Solutions – Now Eleven!

November 2, 2011
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Code Optimization: One R Problem, Ten Solutions – Now Eleven!

Earlier this year I came across a rather interesting page about optimisation in R from rwiki. The goal was to find the most efficient code to produce strings which follow the pattern below given a single integer input n: From this we can see that the general pattern for n is: It is rather heart

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Code Optimization: One R Problem, Ten Solutions – Now Eleven!

November 1, 2011
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Code Optimization: One R Problem, Ten Solutions – Now Eleven!

Earlier this year I came across a rather interesting page about optimisation in R from rwiki. The goal was to find the most efficient code to produce strings which follow the pattern below given a single integer input n: From this we can see that the general pattern for n is: It is rather heart

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Asher’s enigma

July 25, 2010
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Asher’s enigma

On his Probability and statistics blog, Matt Asher put a funny question (with my rephrasing): Take a unit square. Now pick two spots at random along the perimeter, uniformly. For each of these two locations, pick another random point from one of the three other sides of the square and draw the segment. What is

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Le Monde rank test (corr’d)

April 6, 2010
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Le Monde rank test (corr’d)

Since my first representation of the rank statistic as paired was incorrect, here is the histogram produced by the simulation perm=sample(1:20) saple=sum(abs(sort(perm)-sort(perm))) when . It is obviously much closer to zero than previously. An interesting change is that the regression of the log-mean on produces > lm(log(memean)~log(enn)) Call: lm(formula = log(memean) ~ log(enn)) Coefficients: (Intercept)    

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Le Monde rank test

April 4, 2010
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Le Monde rank test

In the puzzle found in Le Monde of this weekend, the mathematical object behind the silly story is defined as a pseudo-Spearman rank correlation test statistic, where the difference between the ranks of the paired random variables and is in absolute value instead of being squared as in the Spearman rank test statistic. I don’t

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New Le Monde puzzle

March 3, 2010
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New Le Monde puzzle

When I first read Le Monde puzzle this weekend, I though it was even less exciting than the previous one: find and , such that is a multiple of . The solution is obtained by brute-force checking through an R program: and then the a next solution is (with several values for N). However, while

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