CODEWITHSUNDEEP
for-loopgnuplot
Shenan
Shenan

Reputation: 545

For-loops in gnuplot

I'm getting confused with how to use for-loops in gnuplot.

The following code works fine:

plot for [quadIter=0:270:90] \
path using 1:(column(1 + quadIter))

It plots 4 curves on one graph.

I also want to plot 4 horizontal lines on the same graph. I have written the following script to do this:

plot for [quadIter=0:270:90] \ 
path using 1:(column(1 + quadIter)) , \
path_to_expt[1 + quadIter/3: 19] \

But it only plots one additional line on the graph, so it is not being included in the for-loop. Please can you tell me how to get the additional line included in the loop?

Also, the constant value that is plotted is not the value I was expecting it would plot. Please can you tell me how to print the value of quadIter to the screen, so that I can check it against the value in the file?

Finally, I tried just to plot the 4 horizontal lines with this script:

plot for [quadIter=0:270:90] \
path_to_expt[1 + quadIter/3: 19] \

But I got an error message, "Non-numeric string found where a numeric expression was expected". I find this strange, as I didn't get this error message when I ran the second script but, as the second script isn't working how I would like, hopefully by getting the second and third scripts to work, I will have a better understanding of how for-loops work in gnuplot.

Thank you for your help!

Upvotes: 0

Views: 6196

Answers (1)

Christoph
Christoph

Reputation: 48390

The for iteration applies only the the current plot expression. The line

plot for [i=1:4] i*x, i*x**2

creates five plots, whereas in order to get eight plots you must do

plot for [i=1:4] i*x, for [i=1:4] i*x**2

Concerning your last expression path_to_expt[1 + quadIter/3: 19]: array expressions aren't supported by gnuplot (however path_to_expt looks like one).

Upvotes: 3

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