Plot multiple ggplot2 on same page

Question

I have a working loop which generates and can save individual plots from each file saved in a directory.

I want to plot all of the returned plots in a single file as

Answer 1

Assuming you need a PDF output where every page has multiple plots plotted as one, e.g.: if there are 12 plots then 4 plots per page.

Try this example:

library(ggplot2)
library(cowplot)

# list of 12 dummy plots, only title is changing.
pltList <- lapply(1:12, function(i){
  ggplot(mtcars,aes(mpg,cyl)) +
    geom_point() +
    ggtitle(paste("Title",i))})

# outputs 3 jpeg files with 4 plots each.
for(i in seq(1,12,4))
ggsave(paste0("Temp",i,".jpeg"),
       plot_grid(pltList[[i]],
                 pltList[[i+1]],
                 pltList[[i+2]],
                 pltList[[i+3]],nrow = 2))

# or we can output into 1 PDF with 3 pages using print
pdf("TempPDF.pdf")
for(i in seq(1,12,4))
  print(plot_grid(pltList[[i]],
            pltList[[i+1]],
            pltList[[i+2]],
            pltList[[i+3]],nrow = 2))
dev.off()

---

EDIT:

Another way using gridExtra, as suggested by @user20650:

library(gridExtra)

#output as PDF
pdf("multipage.pdf")

#use gridExtra to put plots together
marrangeGrob(pltList, nrow=2, ncol=2)

dev.off()