/gnuplot-cheatsheet

sample gnuplot scripts showing off basic functionality

Primary LanguageProlog

gnuplot cheatsheet

Detailing common options in my favourite plotting program. This is a work in progress.

Formatting options

Axis logscale settings

set logscale           # enables log base 10 scaling of all axes
set logscale x         # enables log base 10 scaling of x axis
set logscale xy        # enables log base 10 scaling of x and y axes
set logscale x 2       # enables scaling log base 2 of the x axis

Grid and key settings

set grid               # produces a grid, x and y
set grid xtics         # produces vertical grid lines
set grid mxtics        # produces grid on minor x tics in logscale
set key top left       # puts legend at top left
set key center right   # puts legend at center right

Axis range settings

set xrange[xmin:xmax]       # x axis from xmin to xmax
set yrange[ymin:ymax]       # y axis from ymin to ymax

Titles, axis labels and floating labels. Can specify position at x,y or at graph x,y

set title "title"                  # sets title to `title`
set xlabel "label" rotate by 30    # sets x label to `label`, rotates 30 degrees
set xlabel "label" offset 0,-2     # sets x label to `label`, shifts 2 units vertically
set label "label" at (1,1)         # places the string `label` at (1,1)

Plots with multiple panels

set multiplot layout m,n title "title"   # m by n multiplot, titled `title`
set [lrtb]margin 5                       # sets left, right, top, bottom margin

Set the format of x and y tic lables

  • set format x "%t"; set xtics (5,10); p x produces "5.0" and "1.0"
  • set format x "%s"; set xtics (500,1000); p x produces "500" and "1.0"
  • set format x "%+-12.3f"; set xtics (12345); p x produces "+12345.000"
  • set format x "%.2t*10^%+03T"; set xtic (12345); p xproduces "1.23*10^+04"
  • set format x "%s*10^{%S}"; set xtic (12345); p x produces "12.345*10^{3}"
  • set format x "%s %cg"; set xtic (12345); p x produces "12.345 kg"
  • set format x "%.0P pi"; set xtic (6.283185); p x produces "2 pi"
  • set format x "%.0f%%"; set xtic (50); p x produces "50%"
  • set format x "10^{%L}"; set xtic (1,10,100); p x produces 102

Note, sprintf("%d", i) is super helpful if i is a variable, for example in a for loop.

Outputting data to table

  • set table 'file.dat'; p f(x); unset table writes f(x) to file.dat

Error bars

To do

Outputting data to plot

Now we get to the actual plotting commands. Plotting column data. Note that the following shorthand is available,

  • plot is the same as p when beginning a command
  • with is the same as w to specify line type
  • using is the same as u
  • the type of curve is indicated by
    1. l means lines
    2. p means points
    3. lp means linespoints
  • the type of curve is indicated by
    1. lt means linetype
    2. pt means pointtype
    3. dt means dashtype

plotting curves

plotting heat maps

plotting vector fields

polar plots

plotting specific points

set for[i=1:10] arrow from i, graph 0 to i, graph 1 nohead # vertical lines
set object circle at 1,1 radius 0.05 fillcolor rgb 'black' fillstyle solid border

misc

  • p "filename" u 2:3 w p pt 7 ps 0.5 t "titlestring"
  • p "filename"...

run interpreter with arguments

ARG1

call 'fig.plt' 1 2 call 'script.plt' 'file.dat'

call 'scriplt.plt' 1 where file contains a=int(ARG1); p 'file.dat' u 1:a

You can concatenate strings by writing

string1='directory/'
string2='file.dat'
string3=ARG1

p string1.string2 w l,\
  string3 w p

We might call the above with call 'script.plt' 'anotherfile.dat'.

gnuplotrc and ~/.gnuplot

gnuplotrc is a startup file that sets style macros using any combination of the above specifiers. On macOS, this is normally stored in /usr/local/Cellar/gnuplot/*/share/gnuplot/*, where * is version. However, if .gnuplot is present in ~, it overrides gnuplotrc. Use ~/.gnuplot which will persist after version updates. Mine includes something to the effect of

set term qt size 800,600    # specifies terminal type and plot window size
set tics font ",12"         # specifies the font size of axis tics
set key font ",12"          # specifies the font size of legend text

Miscellanea

  • set samples 100 sets the sampling rate for functions to 100

Greek alphabet

To produce greek letters for symbols in figure titles and axis lable, we use symbolic markup. The alphabet... keys s and S through the symbolic markup {/Symbol s} and {/Symbol S} produce the symbols σ and Σ, respectively. For example, set title "{/Symbol b}-decay".

key greek key greek key greek key greek
A Α N Ν a α n ν
B Β O Ο b β o ο
C Χ P Π c χ p π
D Δ Q Θ d δ q θ
E Ε R Ρ e ε r ρ
F Φ S Σ f φ s σ
G Γ T Τ g γ t τ
H Η U Υ h η u υ
I ι W Ω i ι w ω
K Κ X Ξ k κ x ξ
L Λ Y Ψ l λ y ψ
M Μ Z Ζ m μ z ζ

About this file

Above I maintain the gnuplot options and commands that I use most frequently. It is very far from exhaustive and is personal. I update it whenever I learn handy tricks and shorthand. When in doubt I consult a HTML version of the gnuplot documentation. This version, 4.2, is out of date, but still mostly relevant. Up-to-date information can be found here, but unfortunately docs are in pdf formate. Demo are in HTML, which is handy.

Above I list the set commands I use most frequently. For instance, to set all axes to logscale, we specify set logscale. They can by undone using the unset command, for instance, unset logscale. In the interpreter, option status can be verified with the show command, for instance, show logscale will indicate which axes are set to logarithmic, versus linear scale.

Also, note that there is a great number of options, the preceding is a tiny subset that I've found helpful in my own workflow.