# layout {graphics}

### Description

`layout`

divides the device up into as many rows and columns as there are in matrix `mat`

, with the column-widths and the row-heights specified in the respective arguments.

### Usage

layout(mat, widths = rep.int(1, ncol(mat)), heights = rep.int(1, nrow(mat)), respect = FALSE) layout.show(n = 1) lcm(x)

### Arguments

- mat
- a matrix object specifying the location of the next N figures on the output device. Each value in the matrix must be
- widths
- a vector of values for the widths of columns on the device. Relative widths are specified with numeric values. Absolute widths (in centimetres) are specified with the
`lcm()`

function (see examples). - heights
- a vector of values for the heights of rows on the device. Relative and absolute heights can be specified, see
`widths`

above. - respect
- either a logical value or a matrix object. If the latter, then it must have the same dimensions as
`mat`

and each value in the matrix must be either`1`

. - n
- number of figures to plot.
- x
- a dimension to be interpreted as a number of centimetres.

### Details

Figure i is allocated a region composed from a subset of these rows and columns, based on the rows and columns in which i occurs in `mat`

.

The `respect`

argument controls whether a unit column-width is the same physical measurement on the device as a unit row-height.

There is a limit (currently 200) for the numbers of rows and columns in the layout, and also for the total number of cells (10007).

`layout.show(n)`

plots (part of) the current layout, namely the outlines of the next `n`

figures.

`lcm`

is a trivial function, to be used as *the* interface for specifying absolute dimensions for the `widths`

and `heights`

arguments of `layout()`

.

### Values

`layout`

returns the number of figures, N, see above.

### Warnings

These functions are totally incompatible with the other mechanisms for arranging plots on a device: `par(mfrow)`

, `par(mfcol)`

and `split.screen`

.

### References

Murrell, P. R. (1999) Layouts: A mechanism for arranging plots on a page. *Journal of Computational and Graphical Statistics*, **8**, 121--134.

Chapter 5 of Paul Murrell's Ph.D. thesis.

Murrell, P. (2005) *R Graphics*. Chapman & Hall/CRC Press.

### See Also

`par`

with arguments `mfrow`

, `mfcol`

, or `mfg`

.

### Examples

def.par <- par(no.readonly = TRUE) # save default, for resetting... ## divide the device into two rows and two columns ## allocate figure 1 all of row 1 ## allocate figure 2 the intersection of column 2 and row 2 layout(matrix(c(1,1,0,2), 2, 2, byrow = TRUE)) ## show the regions that have been allocated to each plot layout.show(2) ## divide device into two rows and two columns ## allocate figure 1 and figure 2 as above ## respect relations between widths and heights nf <- layout(matrix(c(1,1,0,2), 2, 2, byrow = TRUE), respect = TRUE) layout.show(nf) ## create single figure which is 5cm square nf <- layout(matrix(1), widths = lcm(5), heights = lcm(5)) layout.show(nf) ##-- Create a scatterplot with marginal histograms ----- x <- pmin(3, pmax(-3, stats::rnorm(50))) y <- pmin(3, pmax(-3, stats::rnorm(50))) xhist <- hist(x, breaks = seq(-3,3,0.5), plot = FALSE) yhist <- hist(y, breaks = seq(-3,3,0.5), plot = FALSE) top <- max(c(xhist$counts, yhist$counts)) xrange <- c(-3, 3) yrange <- c(-3, 3) nf <- layout(matrix(c(2,0,1,3),2,2,byrow = TRUE), c(3,1), c(1,3), TRUE) layout.show(nf) par(mar = c(3,3,1,1)) plot(x, y, xlim = xrange, ylim = yrange, xlab = "", ylab = "") par(mar = c(0,3,1,1)) barplot(xhist$counts, axes = FALSE, ylim = c(0, top), space = 0) par(mar = c(3,0,1,1)) barplot(yhist$counts, axes = FALSE, xlim = c(0, top), space = 0, horiz = TRUE) par(def.par) #- reset to default

Documentation reproduced from R 3.0.2. License: GPL-2.