Calling gnuplot from python

Question

I\'ve a python script that after some computing will generate two data files formatted as gnuplot input.

How do I \'call\' gnuplot from python ?

I want to se

Answer 1

I am a bit late, but since it took me some time to make it work, maybe it's worth putting a note. The programs are working with Python 3.3.2 on Windows.

Notice that bytes are used everywhere, not strings (e.g. b"plot x", not simply "plot x"), but in case it's a problem, simply do something like:

"plot x".encode("ascii")

First solution: use communicate to send everything, and close when it's done. One must not forget pause, or the window is closed at once. However, it's not a problem if gnuplot is used to store images in files.

from subprocess import *
path = "C:\\app\\gnuplot\\bin\\gnuplot"
p = Popen([path], stdin=PIPE, stdout=PIPE)
p.communicate(b"splot x*y\npause 4\n")

Second solution: send commands one after another, using stdin.write(...). But, don't forget flush! (this is what I didn't get right at first) And use terminate to close the connection and gnuplot when the job is done.

from subprocess import *
path = "C:\\app\\gnuplot\\bin\\gnuplot"
p = Popen([path], stdin=PIPE, stdout=PIPE)

p.stdin.write(b"splot x*y\n")
p.stdin.flush()
...
p.stdin.write(b"plot x,x*x\n")
p.stdin.flush()
...
p.terminate()