autoscale by part of the dataset

Is there any way to perform autoscale in gnuplot by only the part of the data in the datafile? Reading help, I found, that its possible to use "writeback" option of yrange, plot part of the data, then restore yrange and replot. However, this code does not work:

set yrange [*:*] writeback
f = "datafile.csv"
plot f u 1:2
set yrange restore
replot f u 1:3

It plots only first graph(using data 1:2) and does not plot 1:3 data by replot.开发者_JAVA百科

The commands above show no terminal/output settings. I heard the PNG terminal has issues, so it might be useful to reset it, and define terminal and output after range restore. For example:

set terminal 'unknown'
set yrange [] writeback
f = "datafile.csv"
plot f u 1:2
set yrange restore
set terminal 'png'
replot f u 1:3

Are you maybe looking for something like this:

plot f u 1:($2*0.1), f u 1:($3*2)

Or what are you referring to with auto scale?