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Having dual Celsius and Fahrenheit scales automatically?

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Having dual Celsius and Fahrenheit scales automatically?

Alan Corey
I can't find an example of where these are being set on the fly, and
for outdoor temperatures this is necessary since the ranges won't be
the same year-round.  After years of wishing I had a way to do this,
I've now got an Oregon Scientific temperature sensor outdoors with the
data being received by radio with an rtlsdr dongle, decoded by rtl_433
and formatted into something Gnuplot can plot by some C I wrote.  See
https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=154451&p=1015069#p1015069

The thermometer setup gives me data in Celsius which I can plot fine,
but I'd like to add a Fahrenheit scale as Y2 at the right side.  Best
would be to have Y2 with its own tickmarks based on (Y1 * 1.8) + 32,
but it would be acceptable to have the same tickmarks with different
labels.  I can see how I could manually generate all the tickmarks and
labels within a program, but is there a way to do this in Gnuplot?
I'm aiming at having all this run by a cron job and generate a daily
plot.

I think normally I'd want to set y2range based on what yrange gets set
to automatically.  Or read the Y values at the tickmarks and calculate
new ones for Y2.  I don't want to plot more data, I just want to
calculate another set of tickmarks.  And it needs to change every day.


  Alan Corey
--
Credit is the root of all evil.  - AB1JX

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Re: Having dual Celsius and Fahrenheit scales automatically?

Ethan A Merritt-2
Use the "set link" command (version 5 only)

gnuplot> set link y2 via (y-32)*5./9. inv (y*9./5.)+32
gnuplot> set ytics format "%.0f °F"
gnuplot> set y2tics format "%.0f °C"
gnuplot> set xrange [0:150]
gnuplot> plot x

Imperfect ascii plot using "set term dumb":

        +-------+-------+-------+------+-------+-------+-------+--**

 140 °F +                                                      *** +60 °C

        |                                                  *****   |

        |                                               ****       |

 120 °F +                                            ****          +50 °C

        |                                         ****             |

 100 °F +                                      ****                +40 °C

        |                                   ****                   |

        |                                ***                       +30 °C

  80 °F +                             ***                          +

        |                          ***                             +20 °C

  60 °F +                       ***                                +

        |                   ****                                   |

        |                ****                                      +10 °C

  40 °F +             ****                                         +

        |          ****                                            +0 °C

  20 °F +       ****                                               +

        |    ****                                                  +-10 °C

        | ***                                                      |

   0 °F **------+-------+-------+------+-------+-------+-------+---+

        0       20      40      60     80     100     120     140





On Wed, Jul 27, 2016 at 9:59 AM, Alan Corey <[hidden email]> wrote:

> I can't find an example of where these are being set on the fly, and
> for outdoor temperatures this is necessary since the ranges won't be
> the same year-round.  After years of wishing I had a way to do this,
> I've now got an Oregon Scientific temperature sensor outdoors with the
> data being received by radio with an rtlsdr dongle, decoded by rtl_433
> and formatted into something Gnuplot can plot by some C I wrote.  See
>
> https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=154451&p=1015069#p1015069
>
> The thermometer setup gives me data in Celsius which I can plot fine,
> but I'd like to add a Fahrenheit scale as Y2 at the right side.  Best
> would be to have Y2 with its own tickmarks based on (Y1 * 1.8) + 32,
> but it would be acceptable to have the same tickmarks with different
> labels.  I can see how I could manually generate all the tickmarks and
> labels within a program, but is there a way to do this in Gnuplot?
> I'm aiming at having all this run by a cron job and generate a daily
> plot.
>
> I think normally I'd want to set y2range based on what yrange gets set
> to automatically.  Or read the Y values at the tickmarks and calculate
> new ones for Y2.  I don't want to plot more data, I just want to
> calculate another set of tickmarks.  And it needs to change every day.
>
>
>   Alan Corey
> --
> Credit is the root of all evil.  - AB1JX
>
>
> ------------------------------------------------------------------------------
> What NetFlow Analyzer can do for you? Monitors network bandwidth and
> traffic
> patterns at an interface-level. Reveals which users, apps, and protocols
> are
> consuming the most bandwidth. Provides multi-vendor support for NetFlow,
> J-Flow, sFlow and other flows. Make informed decisions using capacity
> planning
> reports.http://sdm.link/zohodev2dev
> _______________________________________________
> gnuplot-info mailing list
> [hidden email]
> Membership management via:
> https://lists.sourceforge.net/lists/listinfo/gnuplot-info
>
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