doBy (version 4.5-15)

sampleBy: Sampling from a data frame

Description

A data frame is split according to some variables in a formula, and a sample of a certain fraction of each is drawn.

Usage

sampleBy(formula, frac = 0.1, replace=FALSE, data = parent.frame(),systematic=FALSE)

Arguments

formula

A formula defining the grouping of the data frame

frac

The part of data to be sampled.

replace

Is the sampling with replacement

data

A data frame

systematic

Should sampling be systematic.

Value

A data frame

Details

If systematic=FALSE (default) then frac gives the fraction of data sampled. If systematic=TRUE and frac=.2 then every 1/.2 i.e. every 5th observation is taken out.

See Also

orderBy, summaryBy, transformBy, splitBy,

Examples

data(dietox)
sampleBy(formula = ~Evit+Cu, frac=.1, data = dietox)