Filter cells by name

Normally a gtable is considered a matrix when indexing so that indexing is working on the cell layout and not on the grobs it contains. gtable_filter allows you to subset the grobs by name and optionally remove rows or columns if left empty after the subsetting

Usage

gtable_filter(x, pattern, fixed = FALSE, trim = TRUE, invert = FALSE)

Arguments

x

a gtable object

pattern

character string containing a regular expression (or character string for fixed = TRUE) to be matched in the given character vector. Coerced by as.character to a character string if possible. If a character vector of length 2 or more is supplied, the first element is used with a warning. Missing values are allowed except for regexpr, gregexpr and regexec.

fixed

logical. If TRUE, pattern is a string to be matched as is. Overrides all conflicting arguments.

trim

if TRUE, gtable_trim() will be used to trim off any empty cells.

invert

Should the filtering be inverted so that cells matching pattern is removed instead of kept.

Value

A gtable only containing the matching grobs, potentially stripped of empty columns and rows

See also

Other gtable manipulation: gtable_add_cols(), gtable_add_grob(), gtable_add_padding(), gtable_add_rows(), gtable_add_space

Examples

library(grid)
gt <- gtable(unit(rep(5, 3), c("cm")), unit(5, "cm"))
rect <- rectGrob(gp = gpar(fill = "black"))
circ <- circleGrob(gp = gpar(fill = "red"))

gt <- gtable_add_grob(gt, rect, 1, 1, name = "rect")
gt <- gtable_add_grob(gt, circ, 1, 3, name = "circ")

plot(gtable_filter(gt, "rect"))

plot(gtable_filter(gt, "rect", trim = FALSE))

plot(gtable_filter(gt, "circ"))

plot(gtable_filter(gt, "circ", trim = FALSE))