# Blog Archives

## An example of OOP in GNU R using S4 Classes

August 18, 2012
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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...

## Animation basics for a vacation

August 5, 2012
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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...

## Changing function scope in GNU R example

July 26, 2012
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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...

## Emulating dynamic scoping in GNU R

July 21, 2012
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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 <- "global"f1 <- function() cat("f1:", x, "\n")f2 <- function() cat("f2:", e...

## Solving mastermind with R

June 29, 2012
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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...

## Optimal sorting using rpart

June 24, 2012
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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...

## You should not use split in production code

June 7, 2012
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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 <-...

## Cross-valitation variability example, part I

May 26, 2012
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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 ...

## Emulating local static variables in R

May 17, 2012
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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...

## Porting cdplot to ggplot2

May 11, 2012
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Last week I published a post on plotting tables in ggplot2. So the next natural step is to port cdplot to allow simple visualization of categorical variables against a numerical predictor.First part of the story covers binary variables. In th...