Loading column from CSV file as a list assigned to a variable - csv

Question

given is a function f(a,b,x,y) in gnuplot, where we got a 3D-space with x,y,z (using splot).
Also given is a csv file (without any header) of the following structure:
2 4
1 9
6 7
...
Is there a way to read out all the values of the first column and assign them to the variable a? Implicitly it should create something like:
a = [2,1,6]
b = [4,9,7]
The idea is to plot the function f(a,b,x,y) having iterated for all a,b tuples.
I've read through other posts where I hoped it would be related to it such as e.g. Reading dataset value into a gnuplot variable (start of X series). However I could not make any progres.
Is there a way to go through all rows of a csv file with two columns, using the each column value of a row as the parameter of a function?

Answer 1

Say you have the following data file called data:
1 4
2 5
3 6
You can load the 1st and 2nd column values to variables a and b easily using an awk system call (you can also do this using plot preprocessing with gnuplot but it's more complicated that way):
a=system("awk '{print $1}' data")
b=system("awk '{print $2}' data")
f(a,b,x,y)=a*x+b*y # Example function
set yrange [-1:1]
set xrange [-1:1]
splot for [i in a] for [j in b] f(i,j,x,y)
This is a gnuplot-only solution without the need for a system call:
a=""
b=""
splot "data" u (a=sprintf(" %s %f", a, $1), b=sprintf(" %s %f", b, \
$2)):(1/0):(1/0) not, for [i in a] for [j in b] f(i,j,x,y)