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Gnuplot Introduction

Gnuplot Introduction. What is G nuplot. A portable command-line driven graphing utility for Linux/Windows/.... can output most of the picture formats eps / pdf / tex : good for writing academic pictures now added html, javascript : display data on web

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Gnuplot Introduction

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  1. Gnuplot Introduction

  2. What is Gnuplot • A portable command-line driven graphing utility for Linux/Windows/.... • can output most of the picture formats • eps/pdf/tex: good for writing academic pictures • now added html, javascript: display data on web • Can use interactive command and script file • script is good to automate the task!

  3. Interactive plot %gnuplot gnuplot> plot sin(x) gnuplot> gnuplot > set xrange [0:5] gnuplot > replot

  4. commonly use commands • help topic #get help about a topic • replot #repeat last plot command • clear #remove objects in the canvas • set OPTION [VALUE] #specify plot options • set xrange [0:5] #set the horizontal axis range • set multiplot#several plots on the same page • show [all] # show (all) the settings • plot #primary command for drawing figures. • plot sin(x) • plot ‘filename’ using 2:3 with linespointslinetype 1 pointtype 2 title ‘Figure’ • plot ‘filename’ u 2:3 w lplt 1 pt 2 t ‘figure’ #same meaning as above

  5. plot in script %cat sin.plt plot sin(x) #picture disappears without pause, use ‘help pause’ in gnuplot terminal to learn more. pause -1

  6. save plot to a file • define plot terminal • set terminal png #save to png format picture • set output ‘output.png’ #specify the output picture • may other options for different terminals: background color, canvas size, line type, may vary with terminal type • What I often use to plot figures in paper: set terminal postscript eps enhanced monochrome explain: ‘postscriteps’: create .eps figure for latex ‘enhanced’ : allow enhanced text features : subscripts, superscripts, etc. ‘monochrome’: use gray scale color, change to ‘color’ if you want to use color

  7. plot functions • plot – 2D figure, splot– 3D figure • built-in functions: sin, cos, exp, log, log10, sqrt, norm, abs, etc. • define your own function: +, - , *, / , ** • f(x)=5*x**2+1 plot f(x) • plot 3*x+5*sin(x) • splot sin(x)+sin(y)#3D plot

  8. plot text • set title “A Figure” #set the title of the figure • set xlabel “time” #set the x-axis label as time • plot .... title “data 1” # set the legend in a figure • set label 1 “This is {/Symbol p}” at 3.14, 0 #use the x-y coordinate in the plot, use Greek letter for pi • set label 2 “This is a label” #specify the position later • set label 2 at graph 0,0 #using graph coordinate left, bottom of the picture

  9. plot shapes rectangle/ellipse/circle/polygon/arrow • set object 1 rect from 0,0 to 1,4 fc rgb ‘yellow’ fs solid pattern 2 explain: draw rectangle, fc: fill color, fs : fill style fill with yellow colored pattern, pattern type is 2 • set object 2 circle center 2,2, size 1 arc [10:50] explain: draw an arc from 100 to 500, with center (2,2) and radius is 1. • set arrow 1 from 1,1 to 1,2 #arrow from (1,1) to (1,2) • set arrow 2 from 1,1 rto 1,2 #relative position, arrwo from (1,1) to (2,3) • see ‘help polgyon’, ‘help ellipse’

  10. plot data %cat datafile 3.0 .98 3 4 5.3 .97 5 23 2.7 .8 2 18 5.1 .95 4 15 4.0 .7 4 17 4.4 .84 5 20 5.1 .94 3 13 4.5 .89 5 9 5.7 .94 5 1 set datafile separator ‘,’ # if you use “,” to separate fields file=“datafile” set pointsize 2 plot file using 1:2 with points pt 1 #plot using the first and the second column in datafile #you can modify the column data with arithmetic or functions plot file using 1:($2*2) with points pt 2 #plot using the first column and the second column times 2 plot file using 1:(f($2)) with point pt 3 #call function f and apply to column 2

  11. plot range • set xrange [0:5] #define x range • set yrange [0:10] # define y range • plot [0:5][0:10]norm(x) #plot normal distribution function in xrange [0:5], yrange[0:10]

  12. multiplot • plot several figures on the same canvas • plot f1(x), f2(x), ... # put all the plot commands in a sequence • plot f1(x)\n plot f2(x) #use several plot commands dose not work well • Multiplot • set multiplot, unset multiplot • can use several plot commands in multiplot environment • set multiplot layout <rows>, <cols>

  13. Multiplot example #plot side-by-side set multiplot layout 1,2 plot sin(x) plot cos(x) unset multiplot #specify plot positions set multiplot set origin 0,0 set size 0.3,0.3 plot x**2 set origin 04,0.4 set size 0.4,0.4 plot 2x unset multiplot

  14. Decorate your figures • Gnuplot supports hundreds of plot styles %cat measure 1 9 0.2 -0.5 2 11 0.1 -0.4 3 13 0.2 -0.2 4 13.5 1.0 -0.4 5 14 0.1,-0.2 6 16 0.6,-0.7 try the following plot commands set style fill transparent solid 0.2 noborder plot ‘measure' using 1:2:(abs($3)+abs($4)) with circles, ‘measure' using 1:2 with linespoints plot ‘measure’ u 1:2 with histeps plot ‘measure’ u 1:2 with boxes plot ‘measure’ u 1:2:($3*10) with filledcu plot ‘measure’ u 1:2:($2+$3):($2+$4) with yerrorbars, ‘measure’ using 1:2 with boxes

  15. References Find the demos , tutorials and documents at http://www.gnuplot.info/, Visualize your data with gnuplothttp://www.ibm.com/developerworks/linux/library/l-gnuplot/ Display data on webpages http://www.ibm.com/developerworks/aix/library/au-gnuplot/index.html

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