I have 3d data that makes a surface when plotted in 3d:
x1 y1 f(x1, y1)
x1 y2 f(x1, y2)
.. .. ..
x1 yn f(x1, yn)
x2 y1 f(x1, y1)
x2 y2 f(x1, y2)
.. .. ..
x2 yn f(x1, yn)
.
.
I can use gnuplot to get level curve for x=constant by using :
plot "datafile.txt" u 2:3 index 0 //or index 1 etc
How can I get plot for y=constant ?
Thanks for reply in advance...
1st possibility: plot the whole file, and make all unwanted datapoints invalid (NaN or 1/0)
yfix = 5 # the constant y value
plot datafile using (($2 == yfix) ? $1 : NaN):3
2nd possibility: the every specifier
n = 3 # number of the wanted sample in y-direction
plot datafile every ::n::n using 1:3
It takes as option (line increment):(block increment):(first line):(first block):(last line):(last block)
So the command above plots only the n'th line from each block, resp. dataset.
(note: blocks are separated by a single blank line, datasets by an additional second blank line. The latter are specified with index, the former addressed via every)
