gtable: Arrange 'Grobs' in Tables

Description

Tools to make it easier to work with "tables" of 'grobs'. The 'gtable' package defines a 'gtable' grob class that specifies a grid along with a list of grobs and their placement in the grid. Further the package makes it easy to manipulate and combine 'gtable' objects so that complex compositions can be built up sequentially.

Author(s)

Maintainer: Thomas Lin Pedersen thomas.pedersen@posit.co

Authors:

• Hadley Wickham hadley@posit.co

Other contributors:

• Posit Software, PBC [copyright holder, funder]

See Also

Useful links:

• https://gtable.r-lib.org

• https://github.com/r-lib/gtable

• Report bugs at https://github.com/r-lib/gtable/issues

Convert to a gtable

Description

Convert to a gtable

Usage

as.gtable(x, ...)

## S3 method for class 'grob'
as.gtable(x, widths = NULL, heights = NULL, ...)

Arguments

Value

A gtable object

Methods (by class)

• as.gtable(grob): Creates a 1-cell gtable containing the grob.

Row and column binding for gtables.

Description

These functions are the parallels of the matrix/data.frame row and column bindings. As such they work in the same way, except they have to take care of additional attributes within the gtables. Most importantly it needs to take care of the sizing of the final gtable, as the different gtables going in may have different widths or heights. By default it tries to calculate the maximum width/height among the supplied gtables, but other options exists. Further, the relative layering of the grobs in each gtable can be modified or left as-is.

Usage

## S3 method for class 'gtable'
rbind(..., size = "max", z = NULL)

## S3 method for class 'gtable'
cbind(..., size = "max", z = NULL)

Arguments

Value

A gtable object

Examples

library(grid)
a <- rectGrob(gp = gpar(fill = "red"))
b <- circleGrob()
c <- linesGrob()

row <- matrix(list(a, b), nrow = 1)
col <- matrix(list(a, b), ncol = 1)
mat <- matrix(list(a, b, c, nullGrob()), nrow = 2)

row_gt <- gtable_matrix("demo", row, unit(c(1, 1), "null"), unit(1, "null"))
col_gt <- gtable_matrix("demo", col, unit(1, "null"), unit(c(1, 1), "null"))
mat_gt <- gtable_matrix("demo", mat, unit(c(1, 1), "null"), unit(c(1, 1), "null"))

# cbind
c_binded <- cbind(mat_gt, col_gt, size = "first")
plot(c_binded)

# rbind
r_binded <- rbind(mat_gt, row_gt, size = "last")
plot(r_binded)

# Dimensions must match along bind direction
try(cbind(mat_gt, row_gt))

Create a new grob table.

Description

A grob table captures all the information needed to layout grobs in a table structure. It supports row and column spanning, offers some tools to automatically figure out the correct dimensions, and makes it easy to align and combine multiple tables.

Usage

gtable(
  widths = list(),
  heights = list(),
  respect = FALSE,
  name = "layout",
  rownames = NULL,
  colnames = NULL,
  vp = NULL
)

Arguments

Details

Each grob is put in its own viewport - grobs in the same location are not combined into one cell. Each grob takes up the entire cell viewport so justification control is not available.

It constructs both the viewports and the gTree needed to display the table.

Value

A gtable object

Components

There are three basics components to a grob table: the specification of table (cell heights and widths), the layout (for each grob, its position, name and other settings), and global parameters.

It's easier to understand how gtable works if in your head you keep the table separate from it's contents. Each cell can have 0, 1, or many grobs inside. Each grob must belong to at least one cell, but can span across many cells.

Layout

The layout details are stored in a data frame with one row for each grob, and columns:

• t top extent of grob

• r right extent of grob

• b bottom extent of

• l left extent of grob

• z the z-order of the grob - used to reorder the grobs before they are rendered

• clip a string, specifying how the grob should be clipped: either "on", "off" or "inherit"

• name, a character vector used to name each grob and its viewport

You should not need to modify this data frame directly - instead use functions like gtable_add_grob.

See Also

Other gtable construction: gtable_col(), gtable_matrix(), gtable_row(), gtable_spacer

Examples

library(grid)
a <- gtable(unit(1:3, c("cm")), unit(5, "cm"))
a
gtable_show_layout(a)

# Add a grob:
rect <- rectGrob(gp = gpar(fill = "black"))
a <- gtable_add_grob(a, rect, 1, 1)
a
plot(a)

# gtables behave like matrices:
dim(a)
t(a)
plot(t(a))

# when subsetting, grobs are retained if their extents lie in the
# rows/columns that retained.

b <- gtable(unit(c(2, 2, 2), "cm"), unit(c(2, 2, 2), "cm"))
b <- gtable_add_grob(b, rect, 2, 2)
b[1, ]
b[, 1]
b[2, 2]

# gtable have row and column names
rownames(b) <- 1:3
rownames(b)[2] <- 200
colnames(b) <- letters[1:3]
dimnames(b)

Add new columns in specified position.

Description

Insert new columns in a gtable and adjust the grob placement accordingly. If columns are added in the middle of a grob spanning multiple columns, the grob will continue to span them all. If a column is added to the left or right of a grob, the grob will not span the new column(s).

Usage

gtable_add_cols(x, widths, pos = -1)

Arguments

Value

A gtable with the new columns added.

See Also

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

Examples

library(grid)
rect <- rectGrob(gp = gpar(fill = "#00000080"))
tab <- gtable(unit(rep(1, 3), "null"), unit(rep(1, 3), "null"))
tab <- gtable_add_grob(tab, rect, t = 1, l = 1, r = 3)
tab <- gtable_add_grob(tab, rect, t = 1, b = 3, l = 1)
tab <- gtable_add_grob(tab, rect, t = 1, b = 3, l = 3)
dim(tab)
plot(tab)

# Grobs will continue to span over new rows if added in the middle
tab2 <- gtable_add_cols(tab, unit(1, "null"), 1)
dim(tab2)
plot(tab2)

# But not when added to left (0) or right (-1, the default)
tab3 <- gtable_add_cols(tab, unit(1, "null"))
tab3 <- gtable_add_cols(tab3, unit(1, "null"), 0)
dim(tab3)
plot(tab3)

Add a single grob, possibly spanning multiple rows or columns.

Description

This only adds grobs into the table - it doesn't affect the table layout in any way. In the gtable model, grobs always fill up the complete table cell. If you want custom justification you might need to define the grob dimension in absolute units, or put it into another gtable that can then be added to the gtable instead of the grob.

Usage

gtable_add_grob(
  x,
  grobs,
  t,
  l,
  b = t,
  r = l,
  z = Inf,
  clip = "on",
  name = x$name
)

Arguments

Value

A gtable object with the new grob(s) added

See Also

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

Examples

library(grid)

gt <- gtable(widths = unit(c(1, 1), 'null'), heights = unit(c(1, 1), 'null'))
pts <- pointsGrob(x = runif(5), y = runif(5))

# Add a grob to a single cell (top-right cell)
gt <- gtable_add_grob(gt, pts, t = 1, l = 2)

# Add a grob spanning multiple cells
gt <- gtable_add_grob(gt, pts, t = 1, l = 1, b = 2)

plot(gt)

Add padding around edges of table.

Description

This is a convenience function for adding an extra row and an extra column at each edge of the table.

Usage

gtable_add_padding(x, padding)

Arguments

Value

A gtable object

See Also

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

Examples

library(grid)
gt <- gtable(unit(1, "null"), unit(1, "null"))
gt <- gtable_add_grob(gt, rectGrob(gp = gpar(fill = "black")), 1, 1)

plot(gt)
plot(cbind(gt, gt))
plot(rbind(gt, gt))

pad <- gtable_add_padding(gt, unit(1, "cm"))
plot(pad)
plot(cbind(pad, pad))
plot(rbind(pad, pad))

Add new rows in specified position.

Description

Insert new rows in a gtable and adjust the grob placement accordingly. If rows are added in the middle of a grob spanning multiple rows, the grob will continue to span them all. If a row is added above or below a grob, the grob will not span the new row(s).

Usage

gtable_add_rows(x, heights, pos = -1)

Arguments

Value

A gtable with the new rows added.

See Also

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

Examples

library(grid)
rect <- rectGrob(gp = gpar(fill = "#00000080"))
tab <- gtable(unit(rep(1, 3), "null"), unit(rep(1, 3), "null"))
tab <- gtable_add_grob(tab, rect, t = 1, l = 1, r = 3)
tab <- gtable_add_grob(tab, rect, t = 1, b = 3, l = 1)
tab <- gtable_add_grob(tab, rect, t = 1, b = 3, l = 3)
dim(tab)
plot(tab)

# Grobs will continue to span over new rows if added in the middle
tab2 <- gtable_add_rows(tab, unit(1, "null"), 1)
dim(tab2)
plot(tab2)

# But not when added to top (0) or bottom (-1, the default)
tab3 <- gtable_add_rows(tab, unit(1, "null"))
tab3 <- gtable_add_rows(tab3, unit(1, "null"), 0)
dim(tab3)
plot(tab3)

Add row/column spacing.

Description

Adds width space between the columns or height space between the rows, effictvely pushing the existing cells apart.

Usage

gtable_add_col_space(x, width)

gtable_add_row_space(x, height)

Arguments

Value

A gtable with the additional rows or columns added

See Also

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

Examples

library(grid)

rect <- rectGrob()
rect_mat <- matrix(rep(list(rect), 9), nrow = 3)

gt <- gtable_matrix("rects", rect_mat, widths = unit(rep(1, 3), "null"),
                    heights = unit(rep(1, 3), "null"))

plot(gt)

# Add spacing between the grobs
# same height between all rows
gt <- gtable_add_row_space(gt, unit(0.5, "cm"))

# Different width between the columns
gt <- gtable_add_col_space(gt, unit(c(0.5, 1), "cm"))

plot(gt)

Create a single column gtable

Description

This function stacks a list of grobs into a single column gtable of the given width and heights.

Usage

gtable_col(
  name,
  grobs,
  width = NULL,
  heights = NULL,
  z = NULL,
  vp = NULL,
  clip = "inherit"
)

Arguments

Value

A gtable with one column and as many rows as elements in the grobs list.

See Also

Other gtable construction: gtable(), gtable_matrix(), gtable_row(), gtable_spacer

Examples

library(grid)
a <- rectGrob(gp = gpar(fill = "red"))
b <- circleGrob()
c <- linesGrob()
gt <- gtable_col("demo", list(a, b, c))
gt
plot(gt)
gtable_show_layout(gt)

Filter cells by name

Description

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

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))

Returns the height of a gtable, in the gtable's units

Description

Note that unlike heightDetails.gtable, this can return relative units.

Usage

gtable_height(x)

Arguments

Create a gtable from a matrix of grobs.

Description

This function takes a matrix of grobs and create a gtable matching with the grobs in the same position as they were in the matrix, with the given heights and widths.

Usage

gtable_matrix(
  name,
  grobs,
  widths = NULL,
  heights = NULL,
  z = NULL,
  respect = FALSE,
  clip = "on",
  vp = NULL
)

Arguments

Value

A gtable of the same dimensions as the grobs matrix.

See Also

Other gtable construction: gtable(), gtable_col(), gtable_row(), gtable_spacer

Examples

library(grid)
a <- rectGrob(gp = gpar(fill = "red"))
b <- circleGrob()
c <- linesGrob()

row <- matrix(list(a, b, c), nrow = 1)
col <- matrix(list(a, b, c), ncol = 1)
mat <- matrix(list(a, b, c, nullGrob()), nrow = 2)

gtable_matrix("demo", row, unit(c(1, 1, 1), "null"), unit(1, "null"))
gtable_matrix("demo", col, unit(1, "null"), unit(c(1, 1, 1), "null"))
gtable_matrix("demo", mat, unit(c(1, 1), "null"), unit(c(1, 1), "null"))

# Can specify z ordering
z <- matrix(c(3, 1, 2, 4), nrow = 2)
gtable_matrix("demo", mat, unit(c(1, 1), "null"), unit(c(1, 1), "null"), z = z)

Create a single row gtable.

Description

This function puts grobs in a list side-by-side in a single-row gtable from left to right witrh the given widths and height.

Usage

gtable_row(
  name,
  grobs,
  height = NULL,
  widths = NULL,
  z = NULL,
  vp = NULL,
  clip = "inherit"
)

Arguments

Value

A gtable with a single row and the same number of columns as elements in the grobs list

See Also

Other gtable construction: gtable(), gtable_col(), gtable_matrix(), gtable_spacer

Examples

library(grid)
a <- rectGrob(gp = gpar(fill = "red"))
b <- circleGrob()
c <- linesGrob()
gt <- gtable_row("demo", list(a, b, c))
gt
plot(gt)
gtable_show_layout(gt)

Visualise the layout of a gtable.

Description

This function is a simple wrapper around grid::grid.show.layout() that allows you to inspect the layout of the gtable.

Usage

gtable_show_layout(x, ...)

Arguments

Examples

gt <- gtable(widths = grid::unit(c(1, 0.5, 2), c("null", "cm", "null")),
             heights = grid::unit(c(0.2, 1, 3), c("inch", "null", "cm")))
gtable_show_layout(gt)

Create a row/col spacer gtable.

Description

Create a zero-column or zero-row gtable with the given heights or widths respectively.

Usage

gtable_row_spacer(widths)

gtable_col_spacer(heights)

Arguments

Value

A gtable object

See Also

Other gtable construction: gtable(), gtable_col(), gtable_matrix(), gtable_row()

Trim off empty cells.

Description

This function detects rows and columns that does not contain any grobs and removes thewm from the gtable. If the rows and/or columns removed had a non-zero height/width the relative layout of the gtable may change.

Usage

gtable_trim(x)

Arguments

Value

A gtable object

Examples

library(grid)
rect <- rectGrob(gp = gpar(fill = "black"))
base <- gtable(unit(c(2, 2, 2), "cm"), unit(c(2, 2, 2), "cm"))

center <- gtable_add_grob(base, rect, 2, 2)
plot(center)
plot(gtable_trim(center))

col <- gtable_add_grob(base, rect, 1, 2, 3, 2)
plot(col)
plot(gtable_trim(col))

row <- gtable_add_grob(base, rect, 2, 1, 2, 3)
plot(row)
plot(gtable_trim(row))

Returns the width of a gtable, in the gtable's units

Description

Note that unlike widthDetails.gtable, this can return relative units.

Usage

gtable_width(x)

Arguments

Is this a gtable?

Description

Is this a gtable?

Usage

is.gtable(x)

Arguments

Print a gtable object

Description

Print a gtable object

Usage

## S3 method for class 'gtable'
print(x, zsort = FALSE, ...)

Arguments