Blog Archives

Wrapper functions in GNU R

December 26, 2012
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Recently I have been working with GNU R optimization routines a lot. Function optim has a nice trace option that allows to monitor optimization progress. Another standard function optimize has no such feature but it is pos...

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Predictive models in R: a new book in Polish

December 14, 2012
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Predictive models in R: a new book in Polish

Together with Mateusz Zawisza I have just published a new book in Polish on building predictive models in GNU R. It can be bought at Oficyna Wydawnicza SGH. The book presents complete examples of basic data mining processes.Although the book is in Poli...

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Bridge hand distribution: simulation vs exact calculation

December 8, 2012
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Bridge hand distribution: simulation vs exact calculation

Recently I played bridge with my friends. Being frustrated with several consecutive poor hand distributions we asked ourselves a question what is the probability of having a hand good enough for a small slam. A well known rule of thumb is that you need...

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ESSA2013 Conference

November 24, 2012
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ESSA2013 Conference

It has been just announced that during ESSA2013 conference I am planning to organize a special track on "Statistical analysis of simulation models". I hope to get some presentations using GNU R to promote it in social simulation community.It is obvious that GNU R excels in analysis of simulation data. However, very often it can be neatly...

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Possible error in Bayesian bootstrap

November 8, 2012
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Possible error in Bayesian bootstrap

After my last post on Bayesian bootstrap I got a question why the sample from Dirichlet distribution is taken as weights for calculating mean in the procedure and not as weights used for sampling from the original data set. Actually this mistake i...

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Simple Bayesian bootstrap

November 2, 2012
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Bootstrapping is a very popular statistical technique. However, its Bayesian analogue proposed by Rubin (1981) is not very common. I was looking for an example of its implementation in GNU R and could not find one so I decided to write a snippet presen...

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Plotting Watts-Strogatz model

September 21, 2012
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Plotting Watts-Strogatz model

Recently I wanted to reproduce Figure 2 from Watts and Strogatz (1998). The task using igraph is simple but an interesting task was annotation of the resulting plot.Watts-Strogatz model generates graphs that have so called small-world ne...

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Simulation metamodeling with constraints

September 14, 2012
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Simulation metamodeling with constraints

Last week I have posted about using simulation metamodeling to verify results of analytical solution of the model. After posting it I realized that the solution presented there can be improved by using knowledge of simulation model struc...

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Simulation metamodeling with GNU R

September 7, 2012
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Simulation metamodeling with GNU R

I am one of the organizers of ESSA2013 conference that will take place in September 2013 in Warsaw, Poland. The conference scope is social simulation and in particular methods of statistical analysis of simulation output (metamodeling). As we have just issued Call for Papers for the conference so I decided to post a simple example of a metamodel.Recently I had...

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Exporting ctree object to Asymptote

August 25, 2012
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Exporting ctree object to Asymptote

When producing regression or classification trees (standard rpart or ctree from party package) in GNU R I am often unsatisfied with the default plots they produce. One of many possible solutions is to export a tree plot to Asymptote.The ...

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