How do I animate an arrow using gnuplot? [duplicate] - c++

Question

I'm trying to animate 2D vector with gnuplot. I want to show one line i.e, one vector at a time.
My Data Structure is as follows: They x,y,u,v
2.24448 0.270645 1.00 1.00
3.24448 0.270645 0.500 1.20
I'm able to create a static plot sing following command:
plot "datam.dat" using 1:2:3:4 with vectors filled head lw 3
Here is the output:
Here is my question: I would like to animate and show one row (i.e,) one vector at a time, how to accomplish this in GNU plot using GIF?
Thanks

Answer 1

Animated GIFs are created with set terminal gif animate. Check help gif for details.
Below is a simple example (tested with gnuplot 5.2). You have to make a new plot for each frame. So, put your plot command into a do for-loop. With every ::i::i you are plotting only the ith line (check help every). If you don't know the total number of lines of your datafile, do stats "YourFile.dat" and the variable STATS_records will tell you this number.
Code:
### animated graph with vectors
reset session
set term gif size 300,300 animate delay 12 loop 0 optimize
set output "AnimateVectors.gif"
# create some dummy data
set angle degrees
N = 60
set samples N
set table $Data
plot [0:360] '+' u (cos($1)):(sin($1)):(sin($1)):(cos($1)) w table
unset table
set xrange[-2.5:2.5]
set yrange[-2.5:2.5]
do for [i=0:N-1] {
plot $Data u 1:2:3:4 every ::i::i w vectors lw 2 lc rgb "red" notitle
}
set output
### end of code
Result:
Addition:
This would be the non-animated version, e.g. in a wxt-terminal.
Code:
### non-animated graph with vectors
reset session
set term wxt size 400,400
# create some dummy data
set angle degrees
N = 60
set samples N
set table $Data
plot [0:360] '+' u (cos($1)):(sin($1)):(sin($1)):(cos($1)) w table
unset table
set xrange[-2.5:2.5]
set yrange[-2.5:2.5]
plot $Data u 1:2:3:4 w vectors lw 1.5 lc rgb "red" notitle
### end of code
Result:
Addition2:
Do you maybe mean something like this? A "semi"-animated arrow? By the way, as you can see the arrow look quite different in gif and wxt terminal.
Code:
### "semi"-animated graph with vectors
reset session
set term gif size 300,300 animate delay 12 loop 0 optimize
set output "AnimateVectorsSemi.gif"
# create some dummy data
set angle degrees
N = 60
set samples N
set table $Data
plot [0:360] '+' u (cos($1)):(sin($1)):(sin($1)):(cos($1)) w table
unset table
set xrange[-2.5:2.5]
set yrange[-2.5:2.5]
do for [i=0:N-1] {
plot $Data u 1:2:3:4 every ::0::i w vectors lw 1.5 lc rgb "red" notitle
}
set output
### end of code
Result: