Setup

To plot a graph, create two files in the same directory:

To generate the graph, run:

gnuplot plot.txt

Basic plot Command

The core command reads a data file and plots specified columns. Column indices are 1-based:

plot "data.txt" using 1:2 with lines title "My Data"

To plot multiple datasets on the same graph, separate them with a comma:

plot "data1.txt" using 1:2 with lines title "Series A", \
     "data2.txt" using 1:2 with linespoints title "Series B"

Output Terminals

Set the terminal type before setting the output file. Use pngcairo or pdfcairo for modern conference submissions — they produce sharper output than the older drivers.

Always pair a terminal change with an output file and a fresh plot:

set terminal pngcairo size 800,600
set output "output.png"
plot "data.txt" using 1:2 with lines title "My Data"

Labels, Title and Grid

set title  "Graph Title"
set xlabel "X Axis Label"
set ylabel "Y Axis Label"
set grid

set grid adds a light background grid — useful for readability in academic figures.

Axes — Range, Scale and Tickmarks

Set axis range

set xrange [0:50]
set yrange [0:100]

Logarithmic scale

Common for performance graphs and complexity curves:

set logscale x
set logscale y
set logscale xy   # both axes

Remove mirror tickmarks

set xtics nomirror
set ytics nomirror

Preset tickmark positions on X axis

set xtics (10, 100, 1000, 10000)
# Can be combined: set xtics (10,100,1000,10000) nomirror

Line and Point Styles

Style modifiers can be appended inline to any plot command:

plot "data.txt" using 1:2 with linespoints \
     lw 2 lt 1 pt 7 lc rgb "#2980b9" title "Result"

Use set pointsize 2 to set a global default point size, or set size 5,5 to change the overall plot dimensions.

Legend (Key) Placement

To move the legend to a specific coordinate (e.g. x=3, y=4):

set key 3, 4

Or use named positions:

set key top left
set key bottom right
set key off   # hide legend entirely

Superscript, Subscript and Greek Symbols

Enhanced PostScript mode must be enabled in plot.txt for these to work. Change 16 to your desired font size:

set terminal postscript eps enhance 16

Superscript and Subscript

Use braces to group multiple characters:

Overbar and Underbar

There is no native overbar/underbar option in PostScript, but it can be simulated:

Greek Symbols

Use the {/Symbol ...} syntax:

For the full symbol list, see the PostScript guide PDF from the GNUPlot installation directory. Note: versions 3.5 and earlier do not support these PostScript options.