Gnuplot, how can I count rows and columns of a matrix input of my gnuplot script?

Question

I'm trying to create a heatmap with gnuplot. In input I have a matrix with N rows and M columns but the axis should be always label with numbers going from 0 to 1. I'm not exactly sure about the best way to count the lines and rows of my input matrix.

To show you some code:

set term png
set out "test.png"
set pm3d map
set size ratio 1
set pm3d interpolate 0,0
set tics out nomirror
splot 'test.dat' matrix using ($1/N):($2/M):3 notitle
set out

How can I calculate M and N in this script?

ewcz · Accepted Answer · 2018-02-04 15:03:06Z

2

you could use:

stats 'test.dat' nooutput
N = STATS_records
M = STATS_columns

before invoking splot

answered Feb 4, 2018 at 15:03

ewcz

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2 Comments

heapOverflow Over a year ago

Your solution works! What is weird is that now my chart doesn't cover all the allowed space of the chart, as it did before, but leaves a few pixels uncovered in the top and right sides, where I see the grid behind. Any idea why?

heapOverflow Over a year ago

Solved this problem by using N-1 and M-1. Thank you anyway!

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