Re: [babel] how to pass data to gnuplot from another block

[Eric Schulte <schulte.eric@gmail.com>]

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Hi Eric,

The attached works fine for me (using sh since I don't have octave).


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#+name: uptime
#+begin_src sh
  paste <(echo -e "1\n5\n15") <(uptime|sed 's/^.*average: //;s/,//g'|tr ' ' '\n')
#+end_src

#+RESULTS: uptime
|  1 | 0.02 |
|  5 | 0.06 |
| 15 | 0.05 |

#+begin_src gnuplot :var data=uptime :results silent
  set xrange [0:]
  set yrange [0:]
  set title "uptime"
  set xlabel "minutes ago"
  set ylabel "load"
  plot data w lines
#+end_src

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Ensure that the data you're passing into gnuplot is a table and not a
string.  Gnuplot blocks handle tables by writing them to a file, and
then replacing the variable with the file name.  As I recall gnuplot
blocks assume string data already is a file name, so the variable is
replaced directly.

Best,

Eric S Fraga <e.fraga@ucl.ac.uk> writes:

> Hello,
>
> everything I have seen on the list and on Worg seems to indicate that it
> should be possible to pass data from a babel src block to a gnuplot src
> block.  See, for instance, the excellent article on data collection and
> analysis at
>
> http://orgmode.org/worg/org-contrib/babel/examples/data-collection-analysis.html
>
> I don't have R so I have not tried the examples on this page.  However,
> I have tried the following using octave and gnuplot:
>
> #+begin_src org
>   ,#+TITLE:     examplebug.org
>   ,#+AUTHOR:    Eric S Fraga
>   ,* bubble and dew points
>   ,#+name: bubble-point-temperatures
>   ,#+begin_src octave :results raw output
>     A = [   6.86880    6.84941]';
>     B = [1154.646   1206.001]';
>     C = [ 226.046    223.148]';
>     pv = @(T) 10.^(A-B./(T+C));
>     x = 0;
>     res = [];
>     while x<(1+1e-3)
>       f = @(T) 760 - [x (1-x)]*pv(T);
>       T = fsolve(f, 70);
>       printf("| %5.2f | %7.2f | \n", x, T);
>       res = [res; [x T] ];
>       x = x + 0.05;
>     endwhile
>   ,#+end_src
>   
>   ,#+begin_src gnuplot :var data=bubble-point-temperatures :file "bubble.pdf"
>     set terminal pdfcairo mono enhanced font ",12" size 10cm,6cm
>     plot data
>   ,#+end_src
>   
>   ,#+results:
>   [[file:bubble.pdf]]
> #+end_src
>   
> Trying to execute the gnuplot block leads to an error in gnuplot because
> the output of the octave data block is being put directly into the data
> variable instead of into a file whose name is passed to the data
> variable.  The latter happens if the source of the data is a table
> instead of a src block.
>
> I have tried various combinations of output directives for the first src
> block but to no avail.
>
> I have tried this with "emacs -Q", by the way, and my org is up to date
> as of a few minutes ago!
>
> What am I doing wrong please?
>
> Thanks,
> eric

-- 
Eric Schulte
https://cs.unm.edu/~eschulte
PGP: 0x614CA05D