Plotting data with gnuplot from stdin

Question

I have simple python script (smazat.py) that generate some data

for i in range(50):
    print i, i-20

I can make images in windows command line with following command

smazat.py | gnuplot -e "set term png;p '-'" > smazat.png

however when use gnuplot script with the same commands like this

smazat.py | gnuplot smazat.gp > smazat.png

it does not work. What's happening?

Ups, I overlooked that you are on Windows. See my answer for a little python script which passes stdin to stdout and can be used like cat in this situation. — Christoph
– Christoph, Commented Oct 9, 2014 at 11:39

Community · Accepted Answer · 2017-05-23 12:08:44Z

2

If you are on a Unix system, you can use

plot `< cat -`

On Windows, and since you're using python anyway, you can write a small cat.py python script which passes stdin to stdout:

Script cat.py

from __future__ import print_function
import sys
for line in sys.stdin:
    print(line, file=sys.stdout, end='')

Plot file plot.gp

set term png
plot '< python cat.py'

And then call this with

python smazat.py | gnuplot plot.gp > smazat.png

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answered Oct 9, 2014 at 11:39

Christoph

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