version 3, including all changes.
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JohnMcPherson |
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The old-school Unix way of generating graphs from numeric data. It has very verbose documentation, but unfortunately it lacks in practical examples. |
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!!!Hints |
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!! Output format |
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By default, gnuplot creates [X11] windows and draws the graphs to your [XServer]. But that's no good for embedding it into a report, so do: |
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<verbatim> |
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set output "filename.ps" |
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set term postscript color |
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[...] |
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plot [your plot command] |
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</verbatim> |
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If you use [LaTeX], you can get gnuplot to output a LaTeX picture instead of embedding a graphic in your report: |
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<verbatim> |
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set output "foo.tex" |
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set term latex |
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[...] |
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plot [your plot command] |
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</verbatim> |
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JohnMcPherson |
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Note that your latex file should "\usepackage{latexsym}" so that it knows about several shapes that gnuplot outputs (such as \Diamond and \Box). Try "help set term latex" for more info. |
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JohnMcPherson |
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!!Vertical Lines |
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The default is to give a function that calculates "y" for various values of "x", but that makes it difficult to get a vertical line. Do |
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<verbatim> |
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set parametric |
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# vertical line |
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plot 0, t |
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# horizontal |
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plot t, 0 |
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# or just plain old |
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plot 5 |
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</verbatim> |
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!!Multiple columns from the same data file |
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<verbatim> |
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set pointsize 2 |
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# plot [xrange] [yrange] function, function, .... |
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# do columns 3,4 and 6, using the first column for x |
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plot [0:2] [0:100] "input" using 1:3 with linespoints title "3rd", \ |
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"input" u 1:4 w lp t "4th", "input" u 1:6 w lp t "6th" |
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</verbatim> |
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As you see, command names can be shortened, which can |
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make it hard to understand what is happening :) |
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AlastairPorter |
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!!Multiple plots on a single page |
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Say you want to put 2 graphs on a single A4 bit of paper to print it out |
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<verbatim> |
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set terminal postscript portrait |
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set size 1,1 # The documentation recommends you set to full size first |
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set origin 0,0 |
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set output "output.ps" |
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set multiplot # Enter multiplot mode. Your prompt will become 'multiplot>' |
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set size 1,0.5 |
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set origin 0,0 |
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plot "input" using 1:2 with lines |
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set size 1,0.5 |
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set origin 0,0.5 |
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plot "input" using 1:3 with lines |
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unset multiplot # Exit multiplot mode |
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</verbatim> |
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!! Plotting timeseries data |
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<verbatim> |
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set xdata time |
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set timefmt "%H:%M:%S" |
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set xrange ["8:00:00":"18:00:00"] |
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</verbatim> |
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Timestamps in your data file will now be recognised. Gaps in your time data will show up as gaps in the graph. |
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!! Normal distribution |
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Define the following: |
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<verbatim> |
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invsqrt2pi=1.0/sqrt(2.0*pi) |
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normal(x,mu,sigma)=invsqrt2pi/sigma*exp(-0.5*((x-mu)/sigma)**2) |
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</verbatim> |
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Now, if you want a normal distribution with mean 13 and SD 1, you can go |
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<verbatim> |
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plot normal(x,13,1) |
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</verbatim> |
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!! Force a scale |
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<verbatim> |
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set xrange[0:10] |
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set yrange[50:100] |
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</verbatim> |
