R: Parse Trellis formula

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

### See Also

`xyplot`, `Lattice`

[Package lattice version 0.17-17 Index]