multiple ggplots in one page

motivation

• layout multiple ggplots in one page, like subplot function in matlab simply using {grid} package.

library(tidyverse, quietly=TRUE)
library(grid) 

define my_subplot

my_subplot <- function(nrow=3, ncol=1, 
                       height=7, width=7,
                       ggs) {
  # height and width are in unit inch
  # ggs: ggplot objects wrapped as list
  # order of ggs is like matrix(1:length(ggs), nrow, ncol)
  # todo: spanning
  my_layout <- grid.layout(nrow, ncol,
                           heights=unit(rep(height, nrow)/nrow, 
                                        rep("inch", nrow)),
                           widths=unit(rep(width, ncol)/ncol, 
                                       rep("inch", ncol)))
  
  fg <- frameGrob(my_layout)
  n <- length(ggs)
  for (i in 1:n) {
    my_row <- ifelse(i %% nrow == 0, nrow, i %% nrow)
    my_col <- ifelse(i %% nrow == 0, i %/% nrow, (i %/% nrow) + 1)
    fg <- placeGrob(fg, 
                    ggplotGrob(ggs[[i]]),
                    row=my_row, col=my_col)
  }
  fg
}

prepare three ggplots

d <- tibble(t=1:100, y=abs(rnorm(100)))
g1 <- ggplot(d) + geom_point(aes(t, y))
g2 <- ggplot(d) + geom_line(aes(t, y))
g3 <- g1 + geom_line(aes(t, y))

g1

g2

g3

three plots in one page using my_subplot

grid.newpage()
grid.draw(
  my_subplot(
    3, 1,
    3.5, 6.5,
    ggs=list(g1, g2, g3)
  ))

another layout setting

grid.newpage()
grid.draw(
  my_subplot(
    3, 2,
    3.5, 6.5,
    ggs=list(g1, g2, g3, g1, g2, g3)
  ))

references

• Murrell, P. (2005). R graphics. Chapman and Hall/CRC.
• Murrell, P. (2009). R graphics. Wiley Interdisciplinary Reviews: Computational Statistics, 1(2), 216-220.
• Wickham, H., & Grolemund, G. (2016). R for data science: import, tidy, transform, visualize, and model data. ” O’Reilly Media, Inc.”.