G_latticeParseFormula {lattice} R Documentation

## Parse Trellis formula

### Description

this function is used by high level Lattice functions like 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)


### 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.

### 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.

### Author(s)

Saikat DebRoy, Deepayan Sarkar Deepayan.Sarkar@R-project.org

xyplot, Lattice