Monthly Archives: February 2010

R and Sudoku solvers: Plus ca change…

February 25, 2010
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Christian Robert blogged about a particularly heavy-handed solution to last Sunday's Sudoku puzzle in Le Monde. That had my symapthy as I like evolutionary computing methods, and his chart is rather pretty. From there, this spread on to the REvolutions blogs where David Smith riffed on it, and showed the acual puzzle. That didn't stop things as Christian blogged once more about...

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R and Sudoku solvers: Plus ca change…

February 25, 2010
By

Christian Robert blogged about a particularly heavy-handed solution to last Sunday's Sudoku puzzle in Le Monde. That had my symapthy as I like evolutionary computing methods, and his chart is rather pretty. From there, this spread on to the REvolutions...

Read more »

R and Sudoku solvers: Plus ca change…

February 25, 2010
By

Christian Robert blogged about a particularly heavy-handed solution to last Sunday's Sudoku puzzle in Le Monde. That had my symapthy as I like evolutionary computing methods, and his chart is rather pretty. From there, this spread on to the REvolutions blogs where David Smith riffed on it, and showed the acual puzzle. That didn't stop things as Christian blogged once more about...

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Welcome, Robin!

February 25, 2010
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Welcome, Robin!

Robin Ryder started his new blog with his different solutions to Le Monde puzzle of last Saturday (about the algebraic sum of products…), solutions that are much more elegant than my pedestrian rendering. I particularly like the one based on the Jacobian of a matrix! (Robin is doing a postdoc in Dauphine and CREST—under my

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Responding to the Flowingdata GDP Graph Challenge

February 25, 2010
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Responding to the Flowingdata GDP Graph Challenge

Nathan Yau of Flowingdata put up a challenge earlier today to improve upon a graph showing government spending as a percentage of GDP, published in the Economist. The underlying data wasn’t available. So I put on my graph-to-numbers glasses on and pulled out some data. Here it is in case you want to have a

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Nutritional supplements efficacy score – Graphing plots of current studies results (using R)

February 25, 2010
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Nutritional supplements efficacy score – Graphing plots of current studies results (using R)

In this post I showcase a nice bar-plot and a balloon-plot listing recommended Nutritional supplements , according to how much evidence exists for thier benefits, scroll down to see it(and click here for the data behind it) * * * * The gorgeous blog “Information Is Beautiful” recently publish an eye candy post showing a “balloon race” image...

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Solving Sudoku with Simulated Annealing

February 25, 2010
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Solving Sudoku with Simulated Annealing

How long would it take you to solve this devlishly hard Sudoku puzzle (from Le Monde)? You could do it the old-fashioned way -- with a pencil -- but Xi'an decided to solve it by programming a simulated annealing solver in R. The algorithm works by first guessing a solution at random -- filling in the empty cells above...

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inkblot: an alternative to stacked bar graphs

February 25, 2010
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inkblot: an alternative to stacked bar graphs

Sometimes it is not easy to get useful information from a stacked bar chart, see for instance this blogpost at Support Analytics.So-called inkblot charts, as discussed at Kaiser Fung's Junk Charts, allow the reader to focus on the evolution of a time series.Now how to make this kind of charts with R? I asked on StackOverflow....

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Interaction plot from cell means

February 24, 2010
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Interaction plot from cell means

I needed to produce a few a interaction plots for my book in R and, while the interaction.plot() function is useful it has a couple of drawbacks. First, the default output isn't very pretty. Second, it works from the raw data, whereas I often need plot...

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FFT (Fast Fourier Transform) of time series — promises and pitfalls towards trading

February 24, 2010
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FFT (Fast Fourier Transform) of time series  — promises and pitfalls towards trading

Fig 1. FFT transformed time series (EBAY) reconstructed with first three and twenty harmonics, respectively.I see quite a few traders interested in advanced signal processing techniques. It is often instructive to see why they may or may not be useful....

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