IDPmisc (version 0.9.3)

draw.leg: Produce a Legend or Key (Grid Function)

Description

Produces (and possibly draws) a Grid frame grob which is a legend that can be placed in other Grid plots. draw.leg is a slightly enhanced version of draw.key in package lattice V 0.12-3.

Usage

draw.leg(key, draw=FALSE, vp=NULL)

Arguments

key

A list determining the key. See details below and the documentation for xyplot.

draw

logical, whether the grob is to be drawn.

vp

viewport

Value

• A Grid frame object (that inherits from ``grob'')

Details

Three new components are added to the list key of the original code in package lattice V 0.12-3: between.rows, between.title, adj.title. They allow to format the legend in a more flexible way. To ease the use of draw.leg, the full description of draw.key and the here interesting part of xyplot are also included: \crThekey essentially consists of a number of columns, possibly divided into blocks, each containing some rows. The contents of the key are determined by (possibly repeated) components named ``rectangles'', ``lines'', ``points'' or ``text''. Each of these must be lists with relevant graphical parameters (see later) controlling their appearance. The key list itself can contain graphical parameters, these would be used if relevant graphical components are omitted from the other components. The length (number of rows) of each such column (except ``text''s) is taken to be the largest of the lengths of the graphical components, including the ones specified outside (see the entry for rep below for details on this). The ``text'' component has to have a character or expression vector as its first component, and the length of this vector determines the number of rows. The graphical components that can be included in key (and also in the components named ``text'', ``lines'', ``points'' and ``rectangles'' as appropriate) are:

• cex=1
• col="black"
• lty=1
• lwd=1
• font=1
• fontface
• fontfamily
• pch=8
• adj=0
• type="l"
• size=5
• angle=0
• density=-1

adj, angle and density are currently unimplemented. size determines the width of columns of rectangles and lines in character widths. type is relevant for lines; "l" denotes a line, "p" denotes a point, and "b" and "o" both denote both together. Other possible components of key are: [object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

See Also

xyplot

Examples

grid.newpage()
key <- draw.leg(key = list(rectangles = list(col=1:3,
                           size = 2,
                           lwd = 0.5),
                  text=list(LETTERS[1:3]),
                  cex=1.2,
                  between=2,
                  between.rows=0.5,
                  between.title=0.7,
                  title = "component",
                  cex.title = 1.4,
                  transparent = TRUE))

vp.key <-  viewport(x = convertX(unit(1,"npc")-unit(1,"cm"),"cm"),
                    y = convertY(unit(1,"cm"),"cm"),
                    width=grobWidth(key),
                    height=grobHeight(key),
                    just=c("right","bottom"))
pushViewport(vp.key)
grid.draw(key)
popViewport()

##----------------------------------------
## another example, where the title is left adjusted
key <- draw.leg(key = list(rectangles = list(col=1:3,
                             size = 4,
                             lwd = 0.5),
                  text=list(letters[1:3]),
                  lines=list(col=1:3),
                  cex=2,
                  between=2,
                  between.rows=0.5,
                  between.title=0.7,
                  title = "component",
                  adj.title = 0,
                  cex.title = 2.4,
                  transparent = TRUE))

vp.key <-  viewport(x = 0,
                    y = unit(1,"cm"),
                    width=grobWidth(key),
                    height=grobHeight(key),
                    just=c("left","bottom"))

grid.newpage()
pushViewport(vp.key)
grid.draw(key)
popViewport()