# latticeParseFormula: Parse Trellis formula In lattice: Trellis Graphics for R

 G_latticeParseFormula 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`