[R] Problems outputting ggplot2 graphics to pdf

[Richard M. Heiberger]

You need the print() statement.  See FAQ  7.22 in file
system.file("../../doc/FAQ")


7.22 Why do lattice/trellis graphics not work?
==============================================

The most likely reason is that you forgot to tell R to display the
graph.  Lattice functions such as 'xyplot()' create a graph object, but
do not display it (the same is true of *ggplot2*
(https://CRAN.R-project.org/package=ggplot2) graphics, and Trellis
graphics in S-PLUS).  The 'print()' method for the graph object produces
the actual display.  When you use these functions interactively at the
command line, the result is automatically printed, but in 'source()' or
inside your own functions you will need an explicit 'print()' statement.

On Thu, Mar 2, 2017 at 8:37 AM, Hugh Morgan <h.morgan at har.mrc.ac.uk> wrote:
> Hi All,
>
> I am having trouble outputting ggplot2 graphics to pdf as part of a
> script.  It works if when I pipe the script into R or if I type the
> commands directly into the terminal, but not if I load it using the
> source(..) command.  In this case the outputted pdf is always size 3611,
> and it fails to open with the error "This document contains no pages".
>
> As an example I wrap the create pdf commands around the 1st example in
> ?ggplot:
>
> $ cat test.R
>
> library(ggplot2)
>
> pdf("test.pdf")
>
> df <- data.frame(
>   gp = factor(rep(letters[1:3], each = 10)),
>   y = rnorm(30)
> )
> ds <- plyr::ddply(df, "gp", plyr::summarise, mean = mean(y), sd = sd(y))
> ggplot(df, aes(gp, y)) +
>   geom_point() +
>   geom_point(data = ds, aes(y = mean), colour = 'red', size = 3)
>
> dev.off()
>
> Piping it into R works:
>
> $ R --no-save < test.R
>
> ...
>
> $ ll test.pdf
>
> -rw-rw-r-- 1 user group 4842 Mar  2 13:18 test.pdf
>
> This file opens fine and has a graphic.  If I repeat the process using
> source():
>
> $ R --no-save
>
> R version 3.3.2 (2016-10-31) -- "Sincere Pumpkin Patch"
> ...
>
>> source("test.R")
>>
>
> $ ll test.pdf
> -rw-rw-r-- 1 user group 3611 Mar  2 13:25 test.pdf
>
> This file fails to open, and always has the size 3611.
>
> Any help appreciated,
>
> Hugh
>
>
>
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