I have some data that look like this:
# time Ux Uy sigXX sigYY sigXY
1.e-3 0.001 -0.001 1.e6 0.7e6 2.e5
2.e-3 0.002 -0.0025 2.e6 1.2e6 5.e5
3.e-3 0.004 -0.0035 2.8e6 1.4e6 9.e5
as you can guess the data is in SI units (s, m, Pa), and I'm using gnuplot.
For readability in my plots, I'd like to put the x/ytics in (ms, mm, MPa). This is classically done with using ($..):
set ylabel 'sig[MPa]'
plot 'data.dat' using ($1*1000):($4*1.e-6)
... but adding all those parentheses is getting tedious (as I replot a lot this file). I'm dreaming of something like:
set datafactor $1 1000
set datafactor $4 1.e-6
plot 'data.dat' u 1:4
but couldn't find it yet. I know I could also use redirection and an external script to do the conversion on the fly (I'll post it as an answer if someone's interested), but it seems too complex for such a simple and common task.
Does anyone know how to do this? Is there a native gnuplot way to do this kind of conversion once?
You probably have 3 options:
Option 1 you probably don't want, option 3 you definitely don't want, so, maybe option 2 might be a solution which would be similar to your Python code. You basically load your file into a datablock, scale it and then plot this datablock.
### mulitply data columns with factor
reset session
set table $Data
plot 'data.dat' u ($1*1000):($2*1000):($3*1000):($4*1e-6):($5*1e-6):($6*1e-6) w table
unset table
plot $Data u 1:4
### end of code
Limitations:
Keep in mind, in case you have some comment lines or data separated by single or multiple emtpy lines which in some cases might be essential for plotting, these lines will be all removed when plot ... with table. If you need these empty lines there might be more complicated gnuplot workarounds or you need to call external software.