Gnuplot: vertical space between series titles

问题

How to change the vertical space between series titles. Is it possible to separate the series titles into two groups and have a gap between them, like this one:

Thanks.

回答1:

You can insert some kind of 'dummy' plot where you want to have the white space:

set xrange [0:4]
set key left
plot x, \
     2*x t '2x', \
     NaN title ' ' lt -3,\
     3*x t '3x',\
     4*x t '4x'

The special linetype -3 doesn't draw any line at all, using linewidth 0 wouldn't work for all terminals (e.g. postscript). And the title must contain one space character, otherwise the key entry would be dismissed.

来源：https://stackoverflow.com/questions/23022770/gnuplot-vertical-space-between-series-titles