latticeParseFormula: Parse Trellis formula

In lattice: Trellis Graphics for R

Parse Trellis formula

Description

this function is used by high level Lattice functions such as xyplot to parse the formula argument and evaluate various components of the data.

Usage

latticeParseFormula(model, data, dimension = 2,
                    subset = TRUE, groups = NULL,
                    multiple, outer,
                    subscripts, drop, case.names)

Arguments

model	the model/formula to be parsed. This can be in either of two possible forms, one for 2d and one for 3d formulas, determined by the dimension argument. The 2d formulas are of the form y ~ x| g1 * ... *gn, and the 3d formulas are of the form z ~ x * y | g1 * ... * gn. In the first form, y may be omitted. The conditioning variables g1, ..., gn can be omitted in either case.
data	the environment/dataset where the variables in the formula are evaluated.
dimension	dimension of the model, see above.
subset	index for choosing a subset of the data frame.
groups	the grouping variable, if present.
multiple, outer	logicals, determining how a ‘+’ in the y and x components of the formula are processed. See xyplot for details.
subscripts	logical, whether subscripts are to be calculated.
drop	logical or list, similar to the drop.unused.levels argument in xyplot, indicating whether unused levels of conditioning factors and data variables that are factors are to be dropped.
case.names	either a logical, or a character string giving case names. If TRUE, the row names of data via case.names is used.

Value

Returns a list with several components, including left, right, left.name, right.name, condition for 2-D, and left, right.x, right.y, left.name, right.x.name, right.y.name, condition for 3-D. Other possible components are groups, subscr, and case.names.

Author(s)

Saikat DebRoy, Deepayan Sarkar [e-mail]

See Also

xyplot, Lattice

lattice documentation built on Aug. 12, 2026, 5:06 p.m.