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 ... [Read more...]

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 ... [Read more...]

Recently I have discussed with my friend from WLOG Solutions an implementation of banking cash management engine in GNU R. The code made a nice use of S4 classes so I thought it would be worth showing as an example.The problemEvery commercial bank need... [Read more...]

Since I have a vacation this time I decided to implement some entertaining graphics. I have chosen to animate a Cassini oval.The task is can be accomplished using polar equation:The implementation of the animation is given by the following code:library... [Read more...]

In my last post I have discussed how to work around GNU R scoping rules using environment function. This time let us look at a practical example using recode function from car package.First let us look at how&nbs... [Read more...]

By design GNU R uses lexical scoping. Fortunately it allows for at least two ways to simulate dynamic scoping.Let us start with the example code and next analyze it:x [Read more...]

In my last post I have shown a solution to classical sorting problem in R. So I thought that this time it would be nice to generate a strategy for playing Mastermind using R.It was shown by D.E. Knuth that Mastermind code can be bro... [Read more...]

Some time ago I read a nice post Solving easy problems the hard way where linear regression is used to solve an interesting puzzle. Following the idea I used rpart to find optimal decision tree sorting five elements.It is well known that... [Read more...]

Recently I have stumbled on a problem with split function applied on list of factors. The issue is that it might produce wrong splits when splitting factors contain dots.Here is the example of the problem. Invoking the following code:df [Read more...]

Recently I had a discussion with a student about variability of results obtained from cross-validation procedure. While the subject is well known there are not many examples on the web showing it, so I have written its simple presentation.Results from ... [Read more...]

Recently I was writing a code allowing to plot multiple ggplot2 plots on one page. I wanted to replicate standard behavior of  plot  function that plots graphs in sequence according to  mfrow/ mfcol option in par... [Read more...]

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