DATA MINING Desktop Survival Guide by Graham Williams
Desktop Survival Project Home List of Figures List of Tables Data Mining Data Mining Data Mining with Rattle Introduction Data Transform Explore A Model Building Framework Unsupervised Modelling Two Class Models Multi Class Models Regression Models Text Mining Evaluation and Deployment Moving into R Troubleshooting R for the Data Miner R Data Graphics in R Understanding Data Preparing Data Building Models Evaluating Models Algorithms Apriori Bagging Bayes Classifier Boosting Cluster Analysis Conditional Trees Hierarchical Clustering K-Means K-Nearest Neighbours Linear Models Logistic Regression Neural Networks Support Vector Machines Text Mining Open Products AlphaMiner Borgelt Data Mining Suite KNime R Rattle Weka Closed Products C4.5 Clementine Equbits Foresight GhostMiner InductionEngine ODM Enterprise Miner Statistica Data Miner TreeNet Virtual Predict Appendicies Glossary Bibliography Index

Functions

myfun <- function(arg1, arg2=TRUE, ...)
{
  [...] 
}

The results of a function are returned with the return function (or else is the result of the last evaluated statement in the function). The returned result will be printed if the result is not assigned to a variable. To avoid the result being printed, use the invisible function to return the result.

Anonymous functions can be used:

(function(x, y) x^2 + y^2)(0:5, 1)	#  1  2  5 10 17 2

Functions are first class objects. You can write a function to return a function:

f <- function(y=10) 
{
  g <- function(x) seq(x, x+y)
  return(g)
}
> h <- f(5)
> h(5)
[1]  5  6  7  8  9 10
> h <- f()
> h(5)
 [1]  5  6  7  8  9 10 11 12 13 14 15
> get("y",env=environment(h))
[1] 10

And you can write a function to apply some given function:

chooseFun<-function(dat=1:10,fun=mean,...)fun(dat,...)
chooseFun()
x<-rnorm(100)
chooseFun(x,median)
chooseFun(x,hist)
chooseFun(x,hist,col='gray')

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