1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
|
---
title: "Arranging multiple grobs on a page"
author: "Baptiste Auguie"
date: '`r Sys.Date()`'
vignette: >
%\VignetteEngine{knitr::rmarkdown}
%\VignetteIndexEntry{arrangeGrob: arranging multiple grobs on a page}
output:
knitr:::html_vignette:
toc: yes
---
```{r setup, echo=FALSE, results='hide'}
library(knitr)
opts_chunk$set(message=FALSE, fig.width=4, fig.height=3)
```
The `grid` package provides low-level functions to create graphical objects (`grobs`), and position them on a page in specific `viewports`. The `gtable` package introduced a higher-level layout scheme, arguably more amenable to user-level interaction. With the `arrangeGrob/grid.arrange()` pair of functions, `gridExtra` builds upon `gtable` to arrange multiple grobs on a page.
## Basic usage
In this example we mix a few grobs and plots,
```{r basic}
library(gridExtra)
library(grid)
library(ggplot2)
library(lattice)
p <- qplot(1,1)
p2 <- xyplot(1~1)
r <- rectGrob(gp=gpar(fill="grey90"))
t <- textGrob("text")
grid.arrange(t, p, p2, r, ncol=2)
```
## Title and/or annotations
```{r annotations}
gs <- lapply(1:9, function(ii)
grobTree(rectGrob(gp=gpar(fill=ii, alpha=0.5)), textGrob(ii)))
grid.arrange(grobs=gs, ncol=4,
top="top label", bottom="bottom\nlabel",
left="left label", right="right label")
grid.rect(gp=gpar(fill=NA))
```
## Complex layouts
We can provide a matrix defining the layout,
```{r layout}
lay <- rbind(c(1,1,1,2,3),
c(1,1,1,4,5),
c(6,7,8,9,9))
grid.arrange(grobs = gs, layout_matrix = lay)
```
The layout itself may contain holes, but note that for any given grob index the region must be simply connected (no hole),
```{r holes}
hlay <- rbind(c(1,1,NA,2,3),
c(1,1,NA,4,NA),
c(NA,7,8,9,NA))
select_grobs <- function(lay) {
id <- unique(c(t(lay)))
id[!is.na(id)]
}
grid.arrange(grobs=gs[select_grobs(hlay)], layout_matrix=hlay)
```
All cells are of equal size by default, but users may pass explicity `widths` and/or `heights` in any valid grid units, or as relative numbers (interpreted as `null`),
```{r sizes, fig.height=2}
grid.arrange(grobs=gs[1:3], ncol=2, widths = 1:2,
heights=unit(c(1,10), c("in", "mm")))
```
## Nested layouts with `arrangeGrob`
The `grid.arrange()` function draws on the device; for more complex layouts, we may want to store the gtable and combine it with other objects, e.g. forming nested layouts. To this end, use `arrangeGrob()`,
```{r grob}
g1 <- arrangeGrob(grobs = gs, layout_matrix = t(lay))
g2 <- arrangeGrob(grobs = gs, layout_matrix = lay)
grid.arrange(g1, g2, ncol=2)
```
## Multiple pages output
Finally, we may want to place grobs on multiple pages; the `marrangeGrob()` function provides a convenient interface for this, also compatible with `ggsave()`.
```{r marrange}
set.seed(123)
pl <- lapply(1:11, function(.x)
qplot(1:10, rnorm(10), main=paste("plot", .x)))
ml <- marrangeGrob(pl, nrow=2, ncol=2)
## non-interactive use, multipage pdf
## ggsave("multipage.pdf", ml)
## interactive use; calling `dev.new` multiple times
ml
```
|
