Empty plot gnuplot

Question

I am facing some trouble to make a simple plot. My .gnu file return an empty plot, like this :

I want a heat map, the format of my data is X Y Z in the .gnu file and the header is like this :

cat plot.gnu | head -n 10 :

set size square
set pm3d map corners2color c1
set xlabel ""
set ylabel ""
set yrange [   0.000:3003.000]
set xrange [   0.000:3003.000]
splot "-" with pm3d title "plot.gnu"
1.000 1.000 0
1.000 2.000 0
1.000 3.000 0

and the footer is like this :

cat plot.gnu | tail -n 10 

3002.000 2996.000 0
3002.000 2997.000 0
3002.000 2998.000 0
3002.000 2999.000 0
3002.000 3000.000 0
3002.000 3001.000 0
3002.000 3002.000 0

end
pause -1

EDIT : A shorter script could be :

set size square
set pm3d map corners2color c1
set xlabel ""
set ylabel ""
set yrange [   0.000:4.000]
set xrange [   0.000:4.000]
splot "-" with pm3d title "plot.gnu"
1.000 1.000 1
1.000 2.000 2
1.000 3.000 4
1.000 4.000 5
2.000 1.000 1
2.000 2.000 0
2.000 3.000 3
2.000 4.000 1
3.000 1.000 1
3.000 2.000 0
3.000 3.000 3
3.000 4.000 0
4.000 1.000 9
4.000 2.000 0
4.000 4.000 3
4.000 4.000 2

end
pause -1

Do you have an idea ? Thanks

A guess: your data must contain an empty line whenever the first column changes its value. — Christoph
– Christoph, Commented Sep 2, 2015 at 8:20
Then you must give a short, but complete script which shows the problem and allows us to reproduce it, otherwise its all about guessing... — Christoph
– Christoph, Commented Sep 2, 2015 at 8:38

Christoph · Accepted Answer · 2015-09-02 08:51:45Z

4

The short script gives the warning

Warning: Single isoline (scan) is not enough for a pm3d plot. Hint: Missing blank lines in the data file? See 'help pm3d' and FAQ.

And indeed, your data must be structured differently: isolines, i.e. parts with equal x-values (in your first column), must be separated by single empty lines:

set size square
set pm3d map corners2color c1
set autoscale xfix
set autoscale yfix
splot "-" with pm3d title "plot.gnu"
1.000 1.000 1
1.000 2.000 2
1.000 3.000 4
1.000 4.000 5

2.000 1.000 1
2.000 2.000 0
2.000 3.000 3
2.000 4.000 1

3.000 1.000 1
3.000 2.000 0
3.000 3.000 3
3.000 4.000 0

4.000 1.000 9
4.000 2.000 0
4.000 4.000 3
4.000 4.000 2
e
pause -1

answered Sep 2, 2015 at 8:51

Christoph

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5 Comments

Deuterium Over a year ago

Thanks, I think the real problem was the empty lines I forgot to add, this solved my problem. About the gnuplot warnings, this is strange I could not see any...

Christoph Over a year ago

Indeed strange, that warning exists since almost forever. How do you run the script and which OS and gnuplot version do you have?

Deuterium Over a year ago

I am using Ubuntu 14.04 64-bits and gnuplot 4.0 patchlevel 0

Christoph Over a year ago

Ok, so let's relativate "forever" ;) The warning appears since 4.2.0 (released 2007). Why do you still use 4.0.0? (released in 2004)? Ubuntu 14.04 ships 4.6.4

Deuterium Over a year ago

I should ask this to the informatic service of my laboratory xD... I am not working on my own machine, because it breaks the lab's rules. Also, I have no admin rights to change anything on the lab's machine. But thanks for all.

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