Consider the following file that I want to plot using gnuplot: Servos20211222_105253.csv
# Date/Time 2021/12/22, 10:52:53
# PonE=0,LsKp=200,LsKi=0,LsKd=250,HsKp=40,HsKi=0,HsKd=130,Sp=800,TDEC=1175137
#
# Rel. Time, currentPos, PosPID, currentSpeed, speedPID, Lag, ServoPos
0.00000,4693184,0,0,0,0,4693184
0.00000,4693184,2300,0,368,0,4693184
0.00391,4693185,2300,12,367,0,4693184
:
:
I would like to:
set the plot title to the date/time from the first comment record.
display the record that starts "# PonE" as a caption.
extract the value for TDEC and plot a horizontal line with the name "Target"
I have some influence over the format of the header records, so if (for example) it would be better that they were not comments but provided in some other way, then that can be done.
It is a common problem to get text values from files using only gnuplot. If you can use OS and shell dependent solutions, I'd suggest to use remove the comments from the file and try something like
set title "`head -1 Servos20211222_105253.csv`"
You can place text anywhere using set label <"label text">, where the label text can be the 2nd line from the file.
You can plot a straight line using plot:
p sin(x), 0.5 title "TDEC"
But instead of 0.5, you need to get the value using shell scripts again, e.g. the cut unix command.
There are ways with gnuplot only, although sometimes a bit cumbersome compared with using tools which you have available on Linux (or comparable tools which you need to install on Windows).
Update: shorter and "simplified" script
One possible gnuplot-only way:
set commentschar to nothing, i.e. ''
assign the columns to variables and/or arrays, e.g. myDate, myTime, P[1..9].
Merge P[1..8] into a multi-line string Params by "mis"-using sum (check help sum)
Convert P[9] into a floating point number TDEC for plotting
Script: (modified the data a bit just for illustration)
### extract values from headers with gnuplot only
reset session
$Data <<EOD
# Date/Time 2021/12/22, 10:52:53
# PonE=0,LsKp=200,LsKi=0,LsKd=250,HsKp=40,HsKi=0,HsKd=130,Sp=800,TDEC=1175137
#
# Rel. Time, currentPos, PosPID, currentSpeed, speedPID, Lag, ServoPos
0.00000,1300000,0,0,0,0,4693184
0.00200,1200000,2300,0,368,0,4693184
0.00391,1100000,2300,12,367,0,4693184
EOD
set datafile separator comma commentschar ''
array P[9] # array to store parameters
stats $Data u ($0==0 ? (myDate=strcol(1)[3:], myTime=strcol(2)) : \
sum [_i=1:9] (P[_i] = _i==1 ? strcol(_i)[3:] : strcol(_i) ,0 )) \
every ::0::1 nooutput
set datafile commentschar # set back to default
Params = P[1]
Params = (sum [_i=2:8] (Params=Params.sprintf("\n%s",P[_i]),0),Params)
set title sprintf("%s %s", myDate, myTime)
TDEC = real(P[9][6:]) # convert to real number
set label 1 at graph 0.02, first TDEC P[9] offset 0,-0.7
set label 2 at graph 0.02, graph 0.85 Params
plot $Data u 1:2 w lp pt 7 title "Data", \
TDEC w l lc "red" title "Target"
### end of script
Result:
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:
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:
I have a file with 5 columns of data in it. The first column are x indexes, the second are y indexes and the following three contain some data on which I perform some calculations in my gnuplot script as follows:
module(a,b,c) = sqrt(a**2+b**2+c**2);
splot 'myfile' using 1:2:(module($3,$4,$5)) with image
This works fine. However, if I try to plot the log10 of the module like this:
module(a,b,c) = log10(sqrt(a**2+b**2+c**2));
splot 'myfile' using 1:2:(module($3,$4,$5)) with image
it returns a blank plot and the warning of the title of the question.
I think it might be due to the zeros that are in my data, but even when I set an xy range to avoid those, the error persists.
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:...