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Multiple sources on a common X axis

Robert von Knobloch
Hallo,

I am logging certain industrial processes, with the data in a single file.

Noticing some temperature effects, I have added a temperature sensor,
but this logs, asynchronously, to a second file.

Both files (data and temperature) have timestamps in known fields.

Using multiplot, I would like to be able to align the temperature with
the date/time of the data, so that the correlation between temp and data
can be easily viewed.

The temperature has a different start date and period times.

Is this possible?

Many thanks,

Bob von Knobloch


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Re: Multiple sources on a common X axis

Hans-Bernhard Bröker-2
Am 28.07.2016 um 11:03 schrieb Robert von Knobloch:

> Using multiplot, I would like to be able to align the temperature with
> the date/time of the data, so that the correlation between temp and data
> can be easily viewed.

You really should _not_ be using multiplot for that.  Just plot both
data sets in a single 'plot' command, and you'll be done with it.

I keep wondering how so many people arrive at the belief that they
should be using multiplot for so many jobs it's the completely wrong
tool for.  Is the concept of

        plot 'file1', 'file2'

really that hard to pick up from the documentation and demos?

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Re: Multiple sources on a common X axis

zowie


(Mobile)

> On Jul 28, 2016, at 11:38 AM, Hans-Bernhard Bröker <[hidden email]> wrote:
>
> I keep wondering how so many people arrive at the belief that they
> should be using multiplot for so many jobs it's the completely wrong
> tool for.  Is the concept of
>
>    plot 'file1', 'file2'
>
> really that hard to pick up from the documentation and demos?
>

Actually, yes, I think it is.  Gnuplot uses a different paradigm than most other plotting package: in essence, one is specifying a plot object (axes, frame, etc.) at a time.  Most other plotting packages instead approach the problem from a procedural standpoint: conceptually, one is issuing instructions for how to manipulate a plot object, until it gets to the final desired state.  

That paradigmatic difference between gnuplot and, say, matplotlib could probably do with some introductory material inthegeneral overview at the top of the documentation...





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Re: Multiple sources on a common X axis

Kevin Oberman
In reply to this post by Hans-Bernhard Bröker-2
On Thu, Jul 28, 2016 at 10:38 AM, Hans-Bernhard Bröker <
[hidden email]> wrote:

> Am 28.07.2016 um 11:03 schrieb Robert von Knobloch:
>
> > Using multiplot, I would like to be able to align the temperature with
> > the date/time of the data, so that the correlation between temp and data
> > can be easily viewed.
>
> You really should _not_ be using multiplot for that.  Just plot both
> data sets in a single 'plot' command, and you'll be done with it.
>
> I keep wondering how so many people arrive at the belief that they
> should be using multiplot for so many jobs it's the completely wrong
> tool for.  Is the concept of
>
>         plot 'file1', 'file2'
>
> really that hard to pick up from the documentation and demos?
>
>
> ------------------------------------------------------------------------------
>

In a word, yes!

"set multiplot" just looks like the right thing when you want multiple
plots to one screen or file. The manual makes it look like that is the
answer:
"The command set multiplot places gnuplot in the multiplot mode, in which
several plots are placed on
the same page, window, or screen."

I was lucky enough to read the manual for "plot" and wee that it took
multiple files, each with the standard options for style and it just
worked. But, if you search the manual for "multi", you find "multiplot over
and over along with the repeated (and correct) statement:
"Remember to close the output file before next plot unless in multiplot
mode."  makes it sound like multiplot is the intended tool for placing
multiple data sets onto a single plot when it is actually intended for a
similar, but different purpose.

I wish the "set multiplot" section had something near that top pointing out
that 'plot "file1", "file2", ..." is another, possibly more appropriate
approach.
--
Kevin Oberman, Part time kid herder and retired Network Engineer
E-mail: [hidden email]
PGP Fingerprint: D03FB98AFA78E3B78C1694B318AB39EF1B055683
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Re: Multiple sources on a common X axis

BBands
A one word change should clear that up.

"The command set multiplot places gnuplot in the multiplot mode, in
which several
_independent_ plots are placed on the same page, window, or screen."

    John

On Thu, Jul 28, 2016 at 11:35 AM, Kevin Oberman <[hidden email]> wrote:

> On Thu, Jul 28, 2016 at 10:38 AM, Hans-Bernhard Bröker <
> [hidden email]> wrote:
>
> > Am 28.07.2016 um 11:03 schrieb Robert von Knobloch:
> >
> > > Using multiplot, I would like to be able to align the temperature with
> > > the date/time of the data, so that the correlation between temp and
> data
> > > can be easily viewed.
> >
> > You really should _not_ be using multiplot for that.  Just plot both
> > data sets in a single 'plot' command, and you'll be done with it.
> >
> > I keep wondering how so many people arrive at the belief that they
> > should be using multiplot for so many jobs it's the completely wrong
> > tool for.  Is the concept of
> >
> >         plot 'file1', 'file2'
> >
> > really that hard to pick up from the documentation and demos?
> >
> >
> >
> ------------------------------------------------------------------------------
> >
>
> In a word, yes!
>
> "set multiplot" just looks like the right thing when you want multiple
> plots to one screen or file. The manual makes it look like that is the
> answer:
> "The command set multiplot places gnuplot in the multiplot mode, in which
> several plots are placed on
> the same page, window, or screen."
>
> I was lucky enough to read the manual for "plot" and wee that it took
> multiple files, each with the standard options for style and it just
> worked. But, if you search the manual for "multi", you find "multiplot over
> and over along with the repeated (and correct) statement:
> "Remember to close the output file before next plot unless in multiplot
> mode."  makes it sound like multiplot is the intended tool for placing
> multiple data sets onto a single plot when it is actually intended for a
> similar, but different purpose.
>
> I wish the "set multiplot" section had something near that top pointing out
> that 'plot "file1", "file2", ..." is another, possibly more appropriate
> approach.
>
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Re: Multiple sources on a common X axis

Dave Horsfall
In reply to this post by Hans-Bernhard Bröker-2
On Thu, 28 Jul 2016, Hans-Bernhard Bröker wrote:

> I keep wondering how so many people arrive at the belief that they
> should be using multiplot for so many jobs it's the completely wrong
> tool for.  Is the concept of
>
> plot 'file1', 'file2'
>
> really that hard to pick up from the documentation and demos?

Could it be that there is something wrong with the documentation?

--
Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."
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Re: Multiple sources on a common X axis

theozh
In reply to this post by Kevin Oberman
well, certainly almost all the information you need is somewhere in
documentation, manual and demos.

However, as a beginner, if you stumble across the command "multiplot"
you may believe that this could do the job, although for most cases
"plot" is sufficient.


When I started with gnuplot I was missing comprehensive tutorials (let
me know if I missed one).
A tutorial is not the same as a manual.
Although, there are a lot of introductory tutorials around, most of them
were too basic and soon not sufficient or satisfying anymore. If you
have reached a certain level, you mostly get along with the manual.

More explicit, I missed e.g.
- an overview plot illustrating and explaining the nomenclature of the
axis, labels, tics, coordinates, margins; as well as names and concepts
e.g. for frame, border, margin, canvas, etc. If you do not now how an
object, setting or parameter is named, it is difficult to search for it.
- many tips and tricks... and "how to's"... (which of course is the
intention of the demos).
- updated tips and tricks based on the questions which are asked and
answered e.g. in this newsgroup
- known limits and difficulties what can be done with gnuplot and what
not (and workarounds if there is one).

It took me quite some time to figure out a few things. This might keep
some people away from using gnuplot.

I am wondering whether it is generally possible to write a tutorial
which makes it unnecessary to search the web or to ask (FA)Qs in forums
or newsgroups. Assuming of course that people are reading and following
the tutorial ;-).
This might be a task to linguists to funnel and direct all possible
terms and questions to the right information and instruction in the
tutorial/manual.

I can imagine that is a lot of work to compile the manual. Thanks to all
who have been involved! A comprehensive and understandable step by step
tutorial might be a project on its own.

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Re: Multiple sources on a common X axis

Alan Corey
In reply to this post by Robert von Knobloch
> It took me quite some time to figure out a few things. This might keep
> some people away from using gnuplot.

Who takes time to read documentation?  I mean, I have, but my best
resource for looking up how to do something is to look at how I did it
a year ago.  That's true not only for Gnuplot.

One thing that might help is to somewhere on a web page have tiny
(320x200 or so) thumbnails of different plot types that are linked to
maybe example plot scripts and/or into the documentation where it
talks about using some feature.  I thought Gnuplot had a "concept
index", something I use does, in addition to a normal index.

But that's part of my point, if you use a few dozen different programs
and each one has hundreds of pages of documentation there isn't time
in a lifetime to read it all.  It's good that the documentation
exists, but having maybe a few different ways of finding what you're
looking for in it is good too.  And this seems to be more of a problem
in things written by committees or multiple people or at different
times.  Lazarus for example is potentially a great program with
thousands of pages of documentation spanning a couple decades but you
can't find anything in it.

So I look up how I did it last time.  I use the PDFs and online
documentation too.

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Re: Multiple sources on a common X axis

sfeam
On Friday, 29 July 2016 09:30:30 AM Alan Corey wrote:

> > It took me quite some time to figure out a few things. This might keep
> > some people away from using gnuplot.
>
> Who takes time to read documentation?  I mean, I have, but my best
> resource for looking up how to do something is to look at how I did it
> a year ago.  That's true not only for Gnuplot.
>
> One thing that might help is to somewhere on a web page have tiny
> (320x200 or so) thumbnails of different plot types that are linked to
> maybe example plot scripts and/or into the documentation where it
> talks about using some feature.  I thought Gnuplot had a "concept
> index", something I use does, in addition to a normal index.

      http://gnuplot.sourceforge.net/demo/


>
> But that's part of my point, if you use a few dozen different programs
> and each one has hundreds of pages of documentation there isn't time
> in a lifetime to read it all.  It's good that the documentation
> exists, but having maybe a few different ways of finding what you're
> looking for in it is good too.  And this seems to be more of a problem
> in things written by committees or multiple people or at different
> times.  Lazarus for example is potentially a great program with
> thousands of pages of documentation spanning a couple decades but you
> can't find anything in it.
>
> So I look up how I did it last time.  I use the PDFs and online
> documentation too.
>
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> gnuplot-info mailing list
> [hidden email]
> Membership management via: https://lists.sourceforge.net/lists/listinfo/gnuplot-info


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Documentation [was Re: Multiple sources on a common X axis]

zowie
In reply to this post by Alan Corey
Documentation in general is hard, and presenting information in a way that end-users
can read is a skill that is quite different from presenting it in a way that
works for experts.

My favorite example of the pitfalls was the three-line instruction manual that
used to appear on emacs’ front page by default, back in the 1990s.  It read
something like this:

   The expression “C-“ means to hold down control while pressing the key.
   To load a file, type “C-X F”.  For a self-help tutorial, type “C-H T”.  
   To quit, type “C-X C-C”.

I encountered that text as a graduate student in the Physics Dept. at
Stanford University in 1990.  For the next few years, I would tell new
students in my research group to “just fire up emacs, and follow the
directions to the tutorial”.  Out of about 8-10 people to whom I told that
(remember, these were pretty smart people) zero of them actually found
the self-help tutorial the first try, without being told to read EVERY
WORD of what was on the screen.

It turns out that it’s very hard for people to find text in the middle of other
text — we’re not natural greppers.

The gnuplot documentation suffers from the same sort of fallacy, in spades.
As an expert I still have trouble finding items in it.  For example, I recently
had trouble with single vs. double quotes in our Perl front-end module
(PDL::Graphics::Gnuplot), because despite multiple reads it was not obvious to me
from the documentation that those two types of quote are interchangeable and
behave slightly differently within gnuplot.

That’s not to chastise the team — Ethan and Hans-Bernhard and everyone else
have created (and continue to maintain) something phenomenally useful and
flexible.  Just to acknowledge that many of the support issues on this list
(and tons of “invisible” ones that never get mailed here) reflect a need
to improve the documentation, rather than a failure of the user base
or holes in the code itself.

Cheers,
Craig


> On Jul 29, 2016, at 7:30 AM, Alan Corey <[hidden email]> wrote:
>
>> It took me quite some time to figure out a few things. This might keep
>> some people away from using gnuplot.
>
> Who takes time to read documentation?  I mean, I have, but my best
> resource for looking up how to do something is to look at how I did it
> a year ago.  That's true not only for Gnuplot.
>
> One thing that might help is to somewhere on a web page have tiny
> (320x200 or so) thumbnails of different plot types that are linked to
> maybe example plot scripts and/or into the documentation where it
> talks about using some feature.  I thought Gnuplot had a "concept
> index", something I use does, in addition to a normal index.
>
> But that's part of my point, if you use a few dozen different programs
> and each one has hundreds of pages of documentation there isn't time
> in a lifetime to read it all.  It's good that the documentation
> exists, but having maybe a few different ways of finding what you're
> looking for in it is good too.  And this seems to be more of a problem
> in things written by committees or multiple people or at different
> times.  Lazarus for example is potentially a great program with
> thousands of pages of documentation spanning a couple decades but you
> can't find anything in it.
>
> So I look up how I did it last time.  I use the PDFs and online
> documentation too.
>
> ------------------------------------------------------------------------------
> _______________________________________________
> gnuplot-info mailing list
> [hidden email]
> Membership management via: https://lists.sourceforge.net/lists/listinfo/gnuplot-info
>


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