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

Apply

Suppose you have a data frame from which you wish to extract a subset of rows, and you have a matrix to record the start and finish of the sequences of indicies you wish to extract. Whilst a for loop is obvious, mapply works nicely.

> x <- rbind(c(2,5), c(7,9), c(15,20))
> x
     [,1] [,2]
[1,]    2    5
[2,]    7    9
[3,]   15   20
> unlist(mapply(seq, x[,1], x[,2]))
 [1]  2  3  4  5  7  8  9 15 16 17 18 19 20

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