Loop structure inside gnuplot?

Question

Is there any way to iteratively retrieve data from multiple files and plot them on the same graph in gnuplot. Suppose I have files like data1.txt, data2.txt......data1000.tx

Answer 1

I wanted to use wildcards to plot multiple files often placed in different directories, while working from any directory. The solution i found was to create the following function in ~/.bashrc

plo () {
local arg="w l"
local str="set term wxt size 900,500 title 'wild plotting'
set format y '%g'
set logs
plot"
while [ $# -gt 0 ]
        do str="$str '$1' $arg,"
        shift
done
echo "$str" | gnuplot -persist
}

and use it e.g. like plo *.dat ../../dir2/*.out, to plot all .dat files in the current directory and all .out files in a directory that happens to be a level up and is called dir2.

Answer 2

I have the script all.p

set ...
...
list=system('ls -1B *.dat')
plot for [file in list] file w l u 1:2 t file

Here the two last rows are literal, not heuristic. Then i run

$ gnuplot -p all.p

Change *.dat to the file type you have, or add file types.

Next step: Add to ~/.bashrc this line

alias p='gnuplot -p ~/./all.p'

and put your file all.p int your home directory and voila. You can plot all files in any directory by typing p and enter.

EDIT I changed the command, because it didn't work. Previously it contained list(i)=word(system(ls -1B *.dat),i).

Answer 3

Here is the alternative command:

gnuplot -p -e 'plot for [file in system("find . -name \\*.txt -depth 1")] file using 1:2 title file with lines'

Answer 4

There sure is (in gnuplot 4.4+):

plot for [i=1:1000] 'data'.i.'.txt' using 1:2 title 'Flow '.i

The variable i can be interpreted as a variable or a string, so you could do something like

plot for [i=1:1000] 'data'.i.'.txt' using 1:($2+i) title 'Flow '.i

if you want to have lines offset from each other.

Type help iteration at the gnuplot command line for more info.

Also be sure to see @DarioP's answer about the do for syntax; that gives you something closer to a traditional for loop.

Answer 5

Take a look also to the do { ... } command since gnuplot 4.6 as it is very powerful:

do for [t=0:50] {
  outfile = sprintf('animation/bessel%03.0f.png',t)
  set output outfile
  splot u*sin(v),u*cos(v),bessel(u,t/50.0) w pm3d ls 1
}

http://www.gnuplotting.org/gnuplot-4-6-do/

Answer 6

Use the following if you have discrete columns to plot in a graph

do for [indx in "2 3 7 8"] {
  column = indx + 0
  plot ifile using 1:column ;  
}