R: Create a Grid Graphical Object

grid.grob {grid}

R Documentation

Create a Grid Graphical Object

Description

These functions create grid graphical objects.

Usage

grid.grob(list.struct, cl = NULL, draw = TRUE)
grob(..., name = NULL, gp = NULL, vp = NULL, cl = NULL)
gTree(..., name = NULL, gp = NULL, vp = NULL, children = NULL,
      childrenvp = NULL, cl = NULL)
grobTree(..., name = NULL, gp = NULL, vp = NULL,
         childrenvp = NULL, cl = NULL)
childNames(gTree)
gList(...)
is.grob(x)

Arguments

`...`	For `grob` and `gTree`, the named slots describing important features of the graphical object. For `gList` and `grobTree`, a series of grob objects.
`list.struct`	a `list` (preferably with each element named).
`name`	a character identifier for the grob. Used to find the grob on the display list and/or as a child of another grob.
`children`	a `"gList"` object.
`childrenvp`	a `viewport` object (or `NULL`).
`gp`	A gpar object, typically the output from a call to the function `gpar`. This is basically a list of graphical parameter settings.
`vp`	a `viewport` object (or `NULL`).
`cl`	string giving the class attribute for the `list.struct`.
`draw`	logical indicating whether to produce graphical output.
`gTree`	a `"gTree"` object.
`x`	An R object.

Details

These functions can be used to create a basic "grob", "gTree", or "gList" object, or a new class derived from one of these.

A grid graphical object (“grob”) is a description of a graphical item. These basic classes provide default behaviour for validating, drawing, and modifying graphical objects. Both call the function validDetails to check that the object returned is coherent.

A "gTree" can have other grobs as children; when a gTree is drawn, it draws all of its children. Before drawing its children, a gTree pushes its childrenvp slot and then navigates back up (calls upViewport) so that the children can specify their location within the childrenvp via a vpPath.

Grob names need not be unique in general, but all children of a gTree must have different names. A grob name can be any string, though it is not advisable to use the gPath separator (currently ::) in grob names.

The function childNames returns the names of the grobs which are children of a gTree.

All grid primitives (grid.lines, grid.rect, ...) and some higher-level grid components (e.g., grid.xaxis and grid.yaxis) are derived from these classes.

grobTree is just a convenient wrapper for gTree when the only components of the gTree are grobs (so all unnamed arguments become children of the gTree).

grid.grob is deprecated.

Value

An R object of class "grob", a graphical object.

Author(s)

Paul Murrell