any tool to create illustrative graphs

orion777

Good day!

The problem is not addressed to the Gentoo OS, but maybe somebody knows and can suggest some software to create ILLUSTRATIVE graphs and illustrations.
I means, say, graph of a sinewave: X and Y scales, and a sinevave in the plot. Just to illustrate how do a sinewave looks like, without any values, etc.

Of course, the sinewave can be plotted using, say, MATLAB/Octave, Excel, etc., but all of these software require known equations to build a data to be used in the plot; whereas my graphs are not precise, they just shows how something looks, i.e. sinevawe or, say, p-n junction voltage-current https://www.electroduino.com/wp-content/uploads/2021/04/V-I-Voltage-Vs-Current-Characteristics-of-PN-Junction-Diode.jpg

In software such as paint, gimp. photoshop, etc. I have to carry about each thing: to make arrows of graph X and U scales, the creation of some random graph like PN Voltage-Current curve is also very painfull in the photoshop-like editors...

The software which I'm looking for can be Linux or Windows - does not matter, but it must be user-friendly in creating ILLUSTRATIVE graphs (maybe, controlled only by electric drawing tablets. etc).

fedeliallalinea · Posted: Wed Sep 06, 2023 7:21 am Post subject:

Maybe something like labplot?
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orion777 · Posted: Wed Sep 06, 2023 7:39 am Post subject:

Thanks for the answer!

The lablot is one of the data analysis and DATA VISUALIZATION tools. It means that it, similar to excel/matlab, requires already available DATA to be visualized...

In my case I would like to create ILLUSTRATIVE graphs, say, how output voltage of a generator depends on load; the generator here is a hypothetic, I dont know its parameters to build its exact graphs, so I would like to show just in general something like this: https://2.bp.blogspot.com/-py_VfXisHYM/U7e73SMO4sI/AAAAAAAAA5g/3uMvRY6GPZE/s1600/charateristics-of-shunt-dc-generator.png

fedeliallalinea · Posted: Wed Sep 06, 2023 7:49 am Post subject:

With labplot you can extract data from a image.
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orion777 · Posted: Wed Sep 06, 2023 8:37 am Post subject:

Okay, I didn't know it, thanks! Seems I saw something like this in MATLAB - pickpoint or something like this...

So, by means of labplot I can:
(1) draw a graph by my hand on a paper
(2) scan it
(3) extract point by means of labplot
(4) draw "digital" graph in labplot

Spanik · l33t Joined: 12 Dec 2003 Posts: 943 Location: Belgium

Sorry if I say something stupid, but what about Calc? Just enter some tables and make a graph of it. It draws axis for you, you just need to give it the right names and scale maybe.
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szatox · Advocate Joined: 27 Aug 2013 Posts: 3140

Gnuplot can create 2d and 3d charts from either data points or functions, and you control it from command line, so it's scriptable.

wjb · Posted: Wed Sep 06, 2023 10:31 am Post subject:

Assuming you're after hand-drawn graphs because I literally have no idea what you mean by illustrative graphs, any drawing package will let you draw and adjust bezier curves which makes it dead easy to match any curve you want. GIMP, Krita, Inkscape, Blender, ...

(Blender's in the list because not only can you trace hand scribbled images using images-as-plane, you can also achieve interesting things with the grease pencil these days)

orion777 · Posted: Wed Sep 06, 2023 11:22 am Post subject:

Of course, no problem to plot something (i.e. with calc or excel) if I have the DATA to plot.

But I need illustrative graphs, i.e. I have NO exact data and the graph struture can be complicated (not only a sinewave).

For example A hysteresis loop: how do I can draw it? like this https://www.researchgate.net/figure/Schematic-showing-magnetic-hysteresis-loop-of-a-ferromagnetic-material_fig1_330210801

NichtDerHans · Tux's lil' helper Joined: 27 Jan 2023 Posts: 131

The diagrams are exemplary fake and made with a graphics program. You can try Inkscape or Scribus. This is as you have noticed tinkering.

But you can create such curves with Matplotlib, GNUPlot and remove the axis labels, insert lines, arrows and labels. This is accurate, but a lot of work.

See also here: https://matplotlib.org/stable/gallery/index

Spanik · l33t Joined: 12 Dec 2003 Posts: 943 Location: Belgium

szatox · Advocate Joined: 27 Aug 2013 Posts: 3140

Well, if you have no data for charts and you're not happy with making them up via math functions, there is one more, hardware solution to doing ILLUSTRATIVE graphics:
The cheapest graphic tablets are like 50$ new.

Less effort than pen + paper + scanner and you're getting a cleaner picture (like in: without any noise in background)

sublogic · Posted: Wed Sep 06, 2023 10:09 pm Post subject:

No one mentioned media-gfx/xfig , so I will...

orion777 · Posted: Thu Sep 07, 2023 6:02 am Post subject:

szatox · Advocate Joined: 27 Aug 2013 Posts: 3140

Huh... I see. Alright, time to bring out the biggest guns then: GIMP

It uses layers, so:
Import a template with axes as background.
Import a grid as a new layer (with transparent background)
Create a new transparent layer. Draw your function.
Create a new transparent layer. Enter your text.
Create a new transparent layer for whatever reason
If you later want to change something, just modify or replace the offending layer.

Once you're happy with the result, export image.