Aloha all,
Should :results graphic be documented in the :results header argument
section of the Org-mode manual, or in the R-specific documentation?
All the best,
Tom
On Dec 21, 2010, at 6:57 AM, Dan Davison wrote:
Dan Davison <dandavis...@gmail.com> writes:
Please note the following changes to the way that org-babel handles
file output. These may break existing org-babel files which use
the :file header argument.
:file <filename> should be understood as saying "write the result
to <filename> and return a link to <filename>".
This works for all languages. For graphics languages (e.g. ditaa,
dot,
gnuplot) there is no change in behavior: "result" in the above is the
graphics, and a link to the image is placed in the org buffer. For
general-purpose languages (e.g. emacs-lisp, python, R, ruby, shell),
the "result" written to file is the normal org-babel result (string,
number, table).
This is a backwards-incompatible change for R, which was previously
interpreting :file to mean "send graphics to file". I will send a
separate email concerning R.
Previously R understood :file <filename> to mean "save graphics to
<filename>"[1]; now R behaves like other languages and sends the
normal
org-babel result to file (string, number, table). To tell R to save
graphics[1] to file, use :results graphics.
Some examples:
Wrong!
#+begin_src R :file img.png
hist(rnorm(100))
"img.png is going to contain this string."
#+end_src
Use :results graphics save graphics:
#+begin_src R :file img.png :results graphics
hist(rnorm(100))
"But now img.png is going to contain graphics."
#+end_src
You may want to use `org-babel-default-header-args:R' to make this
more convenient:
#+begin_src emacs-lisp
(setq org-babel-default-header-args:R
'((:results . "graphics")))
#+end_src
Alternatively the :results graphics header can be set in a property
drawer for the subtree, or a #+babel: line, as usual.
Now this will do what was intended
#+begin_src R :file img.png
hist(rnorm(100))
#+end_src
Here is an example of saving something other than base graphics to
file,
and returning a link to the file. Note that :file is not used, and the
filename must be returned. This could be used to save images created
by
non-base graphics libraries:
#+begin_src R :results file :var file="savefile"
write.something.to.file <- function(f) cat("hello", file=f)
write.something.to.file(f=file)
file
#+end_src
Dan
* Footnotes
[1] This only works for "base" graphics.
In order to return a file link from a src block without telling babel
to save any results to that file, use :results <filename> and do not
use :file. The code block can of course write arbitrary content to
<filename>.
Some examples:
Save the output of ls -l as a .csv file (recall that :results value
is
the default):
#+begin_src sh :file dirlisting.csv :sep ,
ls -l
#+end_src
Send the text output of ls -l directly to file:
#+begin_src sh :results output :file dirlisting.txt
ls -l
#+end_src
Dan
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