Various utilities which includes functions for creating groupwise calculations etc.
The core doBy functions were developed to make it easy to split data into groups (defined by the levels of a set of factors) and performing some actions on each of these groups. Thus, these functions mimic what can be achieved using the BY statement in various SAS procedures.
In addition hereto the doBy package containts various other utilities.
Functions summaryBy, splitBy, orderBy, sampleBy, transformBy are the core doBy functions
There is no need for a plotBy function – the xyplot function in the lattice package already fulfills these needs
The esticon function calculates linear functions of parameter estimates under various types of models.
There are various other utility functions in the package.
Søren Højsgaard, [email protected]
data(dietox) summaryBy(Weight+Feed~Evit+Cu+Time, data=dietox, FUN=c(mean,var), na.rm=TRUE, use="pair") orderBy(~Time+Evit, data=dietox) splitBy(formula = ~Evit+Cu, data = dietox) sampleBy(formula = ~Evit+Cu, frac=.1, data = dietox)