Splot triangles from binary data file - gnuplot

I have a binary files that have binary format='%float32%float32%float32', having D3 points (using 1:2:3). Originally logically points grouped by 3 to form triangles. I want to plot just legs of triangles as a lines using with lines. In ASCII data file I can make so-called datablocks by adding an empty line between triples of lines, but in binary I can't. I want to break a chain of lines at every three points to form at least V-like parts of triangle contours.
Is there an option to make gnuplot to treat a triples of points as separate datablocks?
Is there another option to splot the data as (maybe) a solid triangles?

I'm still not sure whether I'm fully on the right track.
The following code writes your binary data into a table and makes groups of 3 datapoints for a triangle, inserting an empty line and then shifted by one for the next triangle.
So, So from the points p1=f1,f2,f3; p2=f4,f5,f6; p3=f7,f8,f9; ... it creates the triangles p1p2p3p1 p2p3p4p2 p3p4p5p3 (space=empty line).
Certainly, not very (memory) efficient, but maybe this gets closer to your final goal.
Check help pm3d and help hidden3d, where you might get some additional information.
I very much hope that there is a better approach.
Code: (assuming the binary file 'myBinary.bin', not sure whether I decoded your ASCII string correctly)
# plot binary data
reset session
# put binary data into a datablock
set table $Data
plot 'myBinary.bin' u 1:2:3 binary format='%float32%float32%float32' skip=12 w table
unset table
# separate each triangle by an empty line
set print $Data2
do for [i=1:|$Data|-2] {
print $Data[i]
print $Data[i+1]
print $Data[i+2]
print $Data[i]
print "" # insert empty line
}
set print
set pm3d hidden3d
set view 40, 24
splot $Data2 u 1:2:3 w pm3d notitle
### end of code
Result:

Related

Spacing between points in graph in gnuplot

As can be seen in the picture attached, the points become too cluttered after a certain point. How do I increase the spacing between points in that region?
Code:
set term jpeg size 1800,900
set output "plot.jpeg"
splot "3d_ME2_31.out" us 1:2:3 lc -1
set grid
set output
I have tried the "every" command but it increasing the spacing in the beginning region too where the point spacing is already high.
Any advice is appreciated. Thanks !
Edit: Data file ( the data to axes mapping is 1:2:3 )
0.94652E+03 0.46588E+02 0.82952E-01
0.94871E+03 0.61601E+02 0.16795E+00
0.95102E+03 0.74087E+02 0.29030E+00
0.95587E+03 0.94012E+02 0.65911E+00
0.95850E+03 0.10204E+03 0.91894E+00
0.96148E+03 0.10885E+03 0.12599E+01
0.96515E+03 0.11542E+03 0.17353E+01
0.96943E+03 0.12040E+03 0.23543E+01
0.97481E+03 0.12578E+03 0.32153E+01
0.98134E+03 0.13077E+03 0.43582E+01
0.98901E+03 0.13507E+03 0.58196E+01
0.99795E+03 0.13948E+03 0.76562E+01
0.10082E+04 0.14377E+03 0.99270E+01
0.10199E+04 0.14800E+03 0.12677E+02
0.10282E+04 0.14775E+03 0.14762E+02
0.10335E+04 0.14413E+03 0.16176E+02
0.10403E+04 0.14050E+03 0.18096E+02
0.10488E+04 0.13621E+03 0.20616E+02
0.10588E+04 0.13205E+03 0.23729E+02
0.10710E+04 0.12798E+03 0.27711E+02
0.10843E+04 0.12370E+03 0.32248E+02
0.10995E+04 0.11973E+03 0.37684E+02
0.11163E+04 0.11572E+03 0.43955E+02
0.11324E+04 0.11203E+03 0.50189E+02
0.11474E+04 0.10875E+03 0.56245E+02
0.11626E+04 0.10553E+03 0.62585E+02
0.11781E+04 0.10217E+03 0.69305E+02
0.11938E+04 0.99038E+02 0.76322E+02
0.12094E+04 0.96412E+02 0.83573E+02
0.12252E+04 0.94002E+02 0.91126E+02
0.12411E+04 0.91794E+02 0.98981E+02
0.12571E+04 0.89765E+02 0.10714E+03
0.12732E+04 0.87918E+02 0.11559E+03
0.12894E+04 0.86536E+02 0.12432E+03
0.13054E+04 0.84701E+02 0.13318E+03
0.13213E+04 0.82945E+02 0.14227E+03
0.13373E+04 0.81284E+02 0.15161E+03
0.13533E+04 0.79678E+02 0.16122E+03
0.13694E+04 0.78071E+02 0.17111E+03
0.13855E+04 0.76542E+02 0.18127E+03
0.14008E+04 0.74960E+02 0.19118E+03
0.14159E+04 0.73330E+02 0.20115E+03
0.14309E+04 0.71898E+02 0.21132E+03
0.14458E+04 0.70357E+02 0.22162E+03
0.14607E+04 0.68300E+02 0.23218E+03
0.14758E+04 0.66454E+02 0.24304E+03
0.14907E+04 0.64530E+02 0.25400E+03
0.15055E+04 0.62676E+02 0.26517E+03
0.15204E+04 0.60999E+02 0.27663E+03
0.15354E+04 0.59429E+02 0.28833E+03
0.15500E+04 0.57764E+02 0.30002E+03
0.15641E+04 0.56109E+02 0.31144E+03
0.15758E+04 0.53850E+02 0.32117E+03
0.15882E+04 0.51118E+02 0.33162E+03
0.16010E+04 0.48445E+02 0.34255E+03
0.16127E+04 0.45813E+02 0.35263E+03
0.16249E+04 0.43266E+02 0.36339E+03
0.16373E+04 0.40811E+02 0.37449E+03
0.16498E+04 0.38485E+02 0.38581E+03
0.16620E+04 0.36479E+02 0.39707E+03
0.16742E+04 0.34549E+02 0.40846E+03
0.16860E+04 0.32632E+02 0.41963E+03
It would be complicated to limit the point reduction to a certain region, but you can do it globally using the pointinterval property of the style with linespoints. If you want to hide the line you can set the linetype to "nodraw": with linespoints lt nodraw pi 5. But that would get you back to the same result as using every to filter the points. The nice thing about using pointinterval instead is that the line goes through all the points even though not all of them are shown. So a jog in the line can highlight an outlier that might otherwise be hidden.
#Plot every 5th point
splot 'DATA' with linespoints pointinterval 5
I would say whether your data points look cluttered or cramped does not only depend on your data but also on your viewpoint.
If you have so many data points why don't you simply plot it with lines? Or as Ethan suggested with linespoints and a certain pointinterval or pointnumber (check help lp).
Script:
set multiplot layout 2,1
set view 60,30
splot $Data u 1:2:3 w p pt 1
set view 71,333
splot $Data u 1:2:3 w p pt 1
unset multiplot
Result: (same datapoints just different viewing angles)

Putting a value from an input data file into 'Set Label'

I'm plotting an animated surface in gnuplot and want to read in an average or sum of the mapped z values and include this in a label to be printed in the plot, so that I get a running total updated as the GIF progresses. It's probably straightforward, but I'm a "gnu"bie, so to speak, and find this system pretty confusing!
I've tried putting the running sum and average numbers in additional columns ...
splot 'output3.dat' index i:i using 1:2:(column(3), TD1 = strcol(4), TD2 = strcol(5)) with pm3d
but this doesn't plot, and the string variables TD1, TD2 don't seem to exist outside the splot command.
The command you show would indeed set variables TD1 and TD2 globally if you change the order of clauses in the serial evaluation expression (the comma-separated sub-expressions):
splot 'output3.dat' index i:i using 1:2:(TD1 = strcol(4), TD2 = strcol(5), column(3)) with pm3d
However, if the idea is to create a label using set label that will appear as part of the resulting graph, this won't work. The set label command would have to be executed before the splot command, so TD1 and TD2 will not have the correct values yet.
There is an alternative that might serve you better. Instead of trying to put this dynamically evaluate information in a label, put it in the plot title. Unlike a label, the plot title is evaluated after the corresponding plot is generated, so any variables set or updated by that plot will be current. [caveat: this is true for current gnuplot (version 5.4) but was not always true. If you have an older gnuplot version the title is evaluated before the plot rather than after].
Since current gnuplot also allows you to place the individual plot titles somewhere other than in the key proper, you have the same freedom that you would with a label to position the text anywhere on the output page. For example, if you want to sum the values in column 3 of the data file and print the total as part of a title above the resulting plot:
SUM = 0
splot 'foo.dat' using 1:2:(SUM = SUM+column(3), column(3)) with linespoints title 'foo.dat', \
keyentry title = sprintf("Points sum to %g", SUM) at screen 0.5 0.9
I used a separate keyentry clause because this allows to omit the sample line segment that would otherwise be generated, but it would also be possible to make this the title of the plot itself if you want that sample line.

Iteratively generate datablocks in gnuplot

Is it possible to iteratively generate datablocks, where the name of the datablock is build up inside the loop?
Let's assume I have three fruits (in reality there are more):
array namelist[3] = ['apple', 'banana', 'pineapple']
I want to create three datablocks with the names $apple_data, $banana_data and $pineapple_data, so I tried the following:
do for [i=1:|namelist|] {
set table '$'.namelist[i]."_data"
plot ...
unset table
}
Unfortunately, instead of datablocks gnuplot created files with these names in the working directory. I guess gnuplot is checking whether the first character after set table is a $?
My second attempt was to remove the apostrophes around $:
set table $.namelist[i]."_data"
But this raised the weird error "Column number or datablock line expected", pointing at the period right after $.
Any ideas on how to achieve that?
The reason for all this is that I read in the banana/apple data files with a lengthy path, apply some lengthy calculations within using, and reuse these for lots of successive stats and plot commands. I would like to avoid having to hard-code and copy-paste the same long path and the cumbersome using command over and over again.
Not sure if I fully understood your detailed intention.
If you only want to avoid typing (or copy pasting) a lengthy path again and again, simply use variables:
FILE1 = 'C:/Dir1/SubDir1/SubSubDir1/SubSubSubDir1/File1'
FILE2 = 'C:/Dir2/SubDir2/SubSubDir2/SubSubSubDir2/File2'
plot FILE1 u 1:2, FILE2 u 1:2
Anyway, you asked for dynamically generated datablocks. One way which comes to my mind is using evaluate, check help evaluate. Check the example below as a starting point, which can probably be simplified.
Code: (simplified thanks to #Eldrad's comment)
### dynamically generate some datablocks
reset session
myNames = 'apple banana pineapple'
myName(i) = word(myNames,i)
N = words(myNames)
set samples 11
do for [i=1:N] {
eval sprintf('set table $%s_data',myName(i))
plot '+' u 1:(rand(0)) w table
unset table
}
plot for [i=1:N] sprintf('$%s_data',myName(i)) w lp pt 7 ti myName(i)
### end of code
Result:

Splot with pattern-filled closed curves and colorbar in Gnuplot

I've got two datafiles that I need to plot, First datafile "surface.dat" is an Nx3 matrix which contains the x y z data.
Am splotting with pm3d and set viewmap to get the 2D projection map of my current surface where the z data defines the range of the colorbar.
The second data file "closed_curve.dat" lies on the x-y plane with no z components. Its very easy to plot the surface and curve in the same graph by using
set view map
set cbrange...
set xrange...
set yrange...
splot "surface.dat" u 2:1:3 title "" w pm3d ,"closed_curve.dat" u 1:2:(0) title ""
Since its a closed curve however, I want to fill it with one of the gnuplot patterns but I can't find anything that works.
A closed curve in the form of a rectangle for example can just be created as an object without the need of a data file and filled in so that's not a problem e.g
set object 1 rectangle from 0,0 to 0.4,0.8 front fc lt 1 fs pattern 2 lw 2
Thanks in advance....
I think your best option is using an external tool to create a polygon object based on your data file:
set macros
polystr = system('awk -v "ORS= " "{printf \"%s %f,%f \",s,\$1,\$2; s = \"to\"}" closed_curve.dat')
set object 1 polygon fillstyle pattern 5 from #polystr
splot "surface.dat" using 2:1:3 with pm3d
I'm not sure if there is any limit on the allowed line length which you may hit with polystr. Maybe you'll need to write the command to a temporary file and the load this.

Gnuplot pm3d plotting from file

I'm having a problem with pm3d. I have data in the format x y # # # #, and I want to add the four #'s and plot their sum versus x,y with something like this:
set pm3d map
splot 'data' 1:2:($3 + $4 + $5+ $6)
I've made sure that my data has lines wherever the first number changes, but I'm getting the error:
';' expected
after data. If I get rid of everything after data then gnuplot is able to plot, but of course the plot is not what I want.
You're missing the keyword using.
splot 'data' using 1:2:($3+$4+$5+$6)
I suppose it's an easy one to miss because in the examples it is often abbreviated u:
splot 'data' u 1:2:...

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