Emacs Orgmode and Gnuplot

I use the emacs editor for nearly everything, including taking notes where I use org-mode. To produce nicely formatted documents, I export to LaTeX and generate PDFs. I recently wanted to include a bar chart in a document and discovered that, yes, org-mode supports that!

I enabled org-babel support in my init.el:

(org-babel-do-load-languages
 'org-babel-load-languages
 '((gnuplot . t)))

In the document I have a section containing the data in an org table. The #+tblname property sets the name used below in the plot. The tag :noexport: prevents the section, and therefore the table, from being rendered:

** DATA TABLE :noexport:
#+tblname: usage
| Year | Sessions |
|------+----------|
| 2013 |      335 |
| 2014 |      217 |
| 2015 |      220 |
| 2016 |      255 |
| 2017 |      255 |
| 2018 |      160 |
| 2019 |       82 |
| 2020 |       15 |
| 2021 |       15 |
| 2022 |      108 |
| 2023 |      147 |
| 2024 |      128 |

I have the following literal which defines the plot, it’s straight forward gnuplot. The enclosing #+begin_src and #+end_src have metadata indicating the name of the table, defined above, from which to source the data and where to send the resulting plot.

#+begin_src gnuplot :var data=usage :results output :file ./usage.pdf
  set title "Children's Literacy Computer Usage"
  set xlabel "Year"
  set yrange[0:375]
  set ind:1
  set style data histogram
  set style histogram cluster gap 1
  set style fill solid
  set terminal pdf
  set boxwidth 2
  plot data using 2:xtic(1) title "Sessions" lt rgb "dark-green", "" using 0:($2+.1):(sprintf("%d",$2)) with labels offset 0,0.5 notitle
#+end_src

Then I insert the results where desired:

#+RESULTS: [[file:./usage.pdf]]

When export is run emacs prompts to generate the plot, which ends up looking like this: