Plotting a table of date+time pairs

Plotting a table of date+time pairs

[Michael Heerdegen]

Hi,

I want to plot two columns of an org table: the first column (the "x"
coordinate) consists of dates, the second column contains a time value
associated with each date.

It seems this is not as easy to do as I had hoped: AFAIU, for making
gnuplot interpret the "y"-value (!) as a time value I need to add
something like

  using "1:(timecolumn(2,\"%H:%M\"))"

to the gnuplot command line (it took me quite a while to find out how to
do it at all...)

And AFAIK this is only possible by tweaking
`org-plot/preset-plot-types'.  I need to add a complete new type of
plot!

Is there maybe a simpler way (I know I could add redundant columns to
the table to help org - that's not really what I want, though)?


TIA,

Michael.

Re: Plotting a table of date+time pairs

[Fraga, Eric]

Response below/inline for email Michael Heerdegen wrote:
> (original email sent 28 Nov 2024 at 02:21)
> 
> [...]
> And AFAIK this is only possible by tweaking
> `org-plot/preset-plot-types'.  I need to add a complete new type of
> plot!

You could use a gnuplot src block instead of org-plot?  It's what I do
usually as org-plot is not powerful enough for most of my plots
(although very nice for simple x-y graphs etc.).

-- 
: Eric S Fraga, with org 9.7.15-a1df10 in Emacs 31.0.50

Re: Plotting a table of date+time pairs

[Michael Heerdegen]

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

> You could use a gnuplot src block instead of org-plot?  It's what I do
> usually as org-plot is not powerful enough for most of my plots
> (although very nice for simple x-y graphs etc.).

Ah ok, thank you.  Sounds reasonable.

I'm not a sophisticated org user.  May I ask for a simple example,
and how I would have to invoke gnuplot instead?


Thank you very much,

Michael.

Re: Plotting a table of date+time pairs

[Fraga, Eric]

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Response below/inline for email Michael Heerdegen wrote:
> (original email sent 29 Nov 2024 at 00:17)
> 
> I'm not a sophisticated org user.  May I ask for a simple example,
> and how I would have to invoke gnuplot instead?

Sure, see attached.  This example has a table of data to plot (simple
example with two columns) and the gnuplot src block to create a PDF
plot.  You invoke gnuplot by typing C-c C-c in the src block.  You can
then view the result with C-c C-o.

Check the info manual for org, specifically
(org) Working with Source Code

HTH,
eric
-- 
: Eric S Fraga, with org 9.7.15-a1df10 in Emacs 31.0.50

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Re: Plotting a table of date+time pairs

[Max Nikulin]

On 29/11/2024 06:17, Michael Heerdegen wrote:
> I'm not a sophisticated org user.  May I ask for a simple example,
> and how I would have to invoke gnuplot instead?

<https://orgmode.org/worg/org-contrib/babel/languages/ob-doc-gnuplot.html>

Link to its source is incorrect, it should be
<https://orgmode.org/worg/org-contrib/babel/languages/ob-doc-gnuplot.org>

Re: Plotting a table of date+time pairs

[Michael Heerdegen]

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

> Sure, see attached.  This example has a table of data to plot (simple
> example with two columns) and the gnuplot src block to create a PDF
> plot.  You invoke gnuplot by typing C-c C-c in the src block.  You can
> then view the result with C-c C-o.
> [...]

Ok... I had to (require 'ob-gnuplot), but then the example worked fine.
It took a while but I got my own table work as well, more or less (see
below).

Thank you very much!


"Max Nikulin" <manikulin@gmail.com> writes:

> <https://orgmode.org/worg/org-contrib/babel/languages/ob-doc-gnuplot.html>

Very nice overview and reference, thank you very much as well.

I now have one remaining problem: my time values in the second column
contain the name of the time zone - the purpose is to flag the time as
summer or winter time.  Currently I need to remove these indicators from
the table, else plotting fail, gnuplot doesn't understand the data.

Can I tell "ob-gnuplot" to export the table in a different way - how?

The time zone makes a difference when exporting since the generated
data file has a different format: the time fields including the timezone
get wrapped in quotation marks, without time zone they are exported
literally.


Thanks again,

Michael.

Re: Plotting a table of date+time pairs

[Michael Heerdegen]

Michael Heerdegen <michael_heerdegen@web.de> writes:

> I now have one remaining problem: my time values in the second column
> contain the name of the time zone - the purpose is to flag the time as
> summer or winter time.  Currently I need to remove these indicators from
> the table, else plotting fail, gnuplot doesn't understand the data.

I could adjust `org-table-number-regexp' - this makes plotting succeed.
Unfortunately does "ob-gnuplot" not respect a buffer local binding of
that variable (in the org buffer containing the table).  I need to
change the global binding of that variable.


Michael.