doBy (version 4.6-2)

by-sample: 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 dataframe.

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

summaryBy, orderBy, splitBy, transformBy

Examples

# NOT RUN {
data(dietox)
sampleBy(formula = ~Evit+Cu, frac=.1, data = dietox)

# }