% latex generated by the script '/home/project-web/bumble/cgi-bin/text2latex.cgi' 
% with help from the sed script 'text2latex.sed' 
% query string: 'books/gnuplot/gnuplot-book' 
% sFileName= 'gnuplot-book' 
% sDirName = 'books/gnuplot' 
% sName = '' -->
% latex by http://bumble.sourceforge.net/scripts/text2latex.sed 
% this script is a work in progress 
\documentclass[11pt]{article} 
\usepackage[hmargin=2cm, vmargin=2cm]{geometry} 
\usepackage{url} 
\usepackage{hyperref} 
\begin{document}

 \\&\\& The Gnuplot Graphing program
 -------------------------------.

 Gnuplot is an amazingly capable program with the usual plethora of
 switches, options, codes, and hidden and secret corners only explored by
 university thesis writers, who occasionally publish a desultory web-page
 describing some serendipitous discovery. 

 Gnuplot can make mathematical graphs and curves as well as bar-charts
 (histograms) along with lots of other things. In this book, the convention
 of writing '\\$>>' may be used to indicate commands which are entered from
 within the gnuplot interpreter.

 @@ \url{http://www.gnuplot.info/}
 The official home page of gnuplot
 @@ \url{http://www.ibm.com/developerworks/library/l-gnuplot/}
 a good tutorial
 @@ \url{http://sparky.rice.edu/gnuplot.html}
 an intro to gnuplot
 @@ \url{http://t16web.lanl.gov/Kawano/gnuplot/plot1-e.html}
 lots of info

 * start the interactive gnuplot shell
 >> gnuplot

HISTORY 

 Originally developed by Colin Kelley and Thomas Williams in 1986

GETTING HELP 

 * view a general help menu with submenu selections
 >> help

 * get help for the gnuplot 'set xrange' command
 >> echo help set xrange | gnuplot

 * display test graphs with example linewidths and pointtypes
 >> test

 * view a list of all keywords setting with the 'set' command
 >> set 

 * view a list of all possible options after the 'with' keyword
 >> plot x with 

COMMAND ABBREVIATIONS

 Any command can be abbreviated to any length as long as there is no
 ambiguity, that is, no other command which could be referenced by the same
 abbreviation (eg 'u' or 'usi' for using) . Other commands have and explicit
 abbreviation (eg 'lt' for 'linetype')


\title{} 
\author{bumble.sourceforge.net} 
\maketitle 
\tableofcontents example
 .. using - 'u', 'usi', 'usin' are all valid abbreviations
 ..

SIMPLE USAGE

 Gnuplot can be used either 'interactively' by starting the gnuplot
 program with the command 'gnuplot' or else it can be used in batch
 mode executing commands to create graphs.

 * start the gnuplot shell and plot a polynomial graph 
 ----------------------------------------------------------
 gnuplot 
 \\# a welcome message is shown and a new 'gnuplot' prompt starts
 plot x**3 + x**2 + x + 1
 \\#the graph is shown in a separate window
 quit 
 \\# exit gnuplot, the graph window is also closed
 ,,,

 * plot a sin curve with x-axis (horizontal axis) -20 to 20 
 >> set xrange [-20:20]
 >> plot sin(x)

 * plot a surface with colorful lines
 >> echo "splot x*x-y*y with line palette" | gnuplot -persist

 * plot a parabola using pipes
 >> echo 'plot x**2' | gnuplot -persist

 * plot sin, cos and tan curves all on the same graph
 >> echo "plot sin(x),cos(x),tan(x)" | gnuplot -persist

 * plot a surface from the bash shell using an 'x' and 'y' range
 >> echo 'splot [x=-4:4] [y=-4:4] sin(x)*cos(y)' | gnuplot -persist

 * plot some random disk usage data of the current folder, labels rotated
 ----------------------------------------------------------------------
 du -s * | shuf | head -10 > temp.txt
 echo '
 set style data histogram
 set xtics rotate by -60
 plot "temp.txt" using 1:xticlabels(2)' | gnuplot -persist
 ,,,


 The 'xticlabels' should refer to the field containing text (not numbers)

 * plot disk usage data from standard input
 >> (echo "set xtic rot;plot '-' u 1:xticl(2)"; du -s \\$\\verb|~|/*)|gnuplot -persist

 * a more verbose version of the same
 ------------------------------------
 (echo "
 set xtics rotate by -45;
 plot '-' using 1:xticlabels(2)"; 
 du -s \\$\\verb|~|/*)|gnuplot -persist
 ,,,

 * create an image of a sin curve graph and display it
 >> echo "se t png; se o 'o.png'; p sin(x)" | gnuplot; feh o.png

 * the same as above but more verbose 
 >> echo "set terminal png; set output 'o.png'; plot sin(x)" | gnuplot; feh o.png

 * plot the graph 'sin(x)' as ascii text
 >> echo "set terminal dumb; plot x**2" | gnuplot -persist
 >> echo "se te du; p sin(x)" | gnuplot -persist \\#\\#(the same)

COMMAND LINE OPTIONS 
AXIS VALUE RANGE

 * plot a sin curve with x-axis -20 to 20, all commands on one line
 >> set xrange [-20:20]; plot sin(x) 
 >> plot [-20:20] sin(x) \\#\\#(the same)

 * plot a sin curve with x-axis -pi to pi ('pi' is a mathematical transcendental)
 >> set xrange [-pi:pi]; plot sin(x) 
 >> plot [-pi:pi] sin(x) \\#\\#(almost the same)

 * plot the function 'y=x' with a y-axis range of [-2:5]
 >> plot [][-2:5] x
 >> plot [ ] [-2:5] x \\#\\#(the same, spaces dont matter)
 >> set yrange [-2:5]; plot x \\#\\#(the same, but persists for next graph) 

 * set the x value range to 0 to a multiple of pi
 >> set xrange [0:2*pi]

 * plot from the command line a 'cos(x)' graph with x-range -20 to 20
 >> echo 'plot [-20:20] cos(x)' | gnuplot -persist

 * create an image of 'sin(x)' with x-range -20 to 20
 >> echo "se t png;se o 'i.png'; p[-20:20] sin(x)" | gnuplot;feh i.png

 * the same as above
 >> echo "set t png;set o 'o.png';plot [-20:20] sin(x)" | gnuplot;feh o.png

USING THE GNUPLOT SHELL

 * plot a curve, add a title and then replot it (which saves some typing)
 >> plot sin(x); set title 'hello'; replot

 * span a single command over several lines with a backslash '\\$\\backslash\\$'
 >> set \\$\\backslash\\$
 >> grid

GRAPH TITLES

 The title of the graph normally appears above the graph and should
 describe it. Each curve or data set should also have a legend to 
 explain it.

 * plot a graph of the sin curve with a graph title 'a simple curve'
 >> echo 'set title "Two Curve"; p sin(x),tan(x)' | gnuplot -persist

 * set the title for just one plot
 >> echo "plot x*x title 'a parabola'" | gnuplot -persist
 >> plot x*x t 'a parabola' \\#\\#(exactly the same)

 * create a multiline title for a half circle graph 
 >> echo 'p [-2:2][0:2](1-x*x)**0.5 title "Half\\$\\backslash\\$nCircle"'|gnuplot -persist

 * plot a curve with the title 'x\\^2 + y\\^2' 
 >> echo 'set title "x\\^2 + y\\^2"; splot x**2+y**2' | gnuplot -persist 

BORDERS AND FRAMES

 The border is the box which surrounds the graph and on which the 
 tick marks are drawn.

ERASING BORDERS ....
 
 To erase some or all or the borders of a graph one must use a 
 sort of binary arithmetic.

 * remove all borders from the graph (but the ticks remain)
 >> set border 0

 * display only the bottom and left borders, tic marks and labels
 >> echo "se bor 3; se tics nomirror; p sin(x)" | gnuplot -persist
 >> echo "se bor 3; se tics nomi; p sin(x)" | gnuplot -persist \\#\\#(the same)

 * display only the bottom and left borders, tic marks and labels
 >> set border 3; set xtics nomirror; set ytics nomirror
 >> set border 3; set tics nomirror \\#\\#(the same, with modern gnuplot)
 >> se bor 3; set tics nomirror \\#\\#(an abbreviated version)
 
 * show the bottom, left, right borders, but not the top, nor the top tics
 >> echo "se bor 11; se xtics nomi; p x**2" | gnuplot -persist
 
 * show no graph border, no tic marks and no value labels for a parabola
 >> unset tics; set border 0; plot x**2
 >> set notics; set border 0; plot x**2 \\#\\#(an older syntax)

 * display only the bottom border for a parabola graph
 >> set border 1; plot x**2


\title{} 
\author{bumble.sourceforge.net} 
\maketitle 
\tableofcontents the graph border 'keys'
 .. 1 - bottom
 .. 2 - left
 .. 4 - top
 .. 8 - right
 ..


\title{} 
\author{bumble.sourceforge.net} 
\maketitle 
\tableofcontents border examples
 .. set border 3 - (1+2) display bottom and left borders
 .. set border 6 - (2+4) display left and top borders
 .. set border 6 - (1+2+4) display bottom, left and top borders
 .. set border 11 - (1+2+8) display the bottom, left, and right borders
 ..

AXIS LABELS

 The axis label is the text which is printed alongside of the 
 vertical (y) or horizontal (x) axis. This text generally explains the
 meaning of the value of that axis, such as 'temperature' or 'date' etc.

 * The formal syntax statement
 -----------------------------
 set xlabel \{"<label>"\} \{offset <offset>\} \{font "<font>\{,<size>\}"\}
 \{\{textcolor | tc\} \{lt <line\\_type> | default\}\} \{\{no\}enhanced\}
 \{rotate by <degrees>\}
 ,,,

 * show the settings which currently apply for the x-axis label
 >> show xlabel

 * suppress the label on the vertical axis (no label is shown)
 >> set ylabel 

 * set the vertical axis label to be the text "degrees"
 >> set ylabel "degrees"
 >> set ylabel 'degrees' \\#\\#(the same, but maybe not for all versions)

 * plot a graph of a parabola (x squared) setting the y-axis label
 >> echo 'set ylabel "the y range"; plot x**2' | gnuplot -persist 
 >> echo 'set yl "the y range"; p x**2' | gnuplot -persist \\#\\#(the same)

 * plot a graph of free disk space setting the y-axis label
 ----------------------------------------------------------
 (echo '
 set style histogram clustered gap 1; set boxwidth 1.5
 set style data histogram 
 set style fill solid
 plot [][0:15] '-' using 2:xticlabels(1)"; 
 \\# the xtic labels are almost vertical upwards
 set xtics rotate by 91 
 set ylabel "1K blocks used"
 plot "-" using 1:xticlabels(2)'
 df| grep [0-9]\\%| tr -s ' '|cut -d' ' -f3,6)| gnuplot -persist 
 ,,,

 * set the y range label succintly
 >> echo 'set yl "Y Value"; p [-20:20] sin(x)/x' | gnuplot -persist 

 * set the y range label succintly
 >> echo 'set yl "Y Value"; p [-40:40] sin(x)/(4*x)' | gnuplot -persist 

 * put a newline character in the y-axis label
 >> set ylabel "Degrees\\$\\backslash\\$ncelsius"
 >> set ylabel 'Degrees\\$\\backslash\\$ncelsius' \\#\\#(No! it doesnt work, no escapes)

 * create \\& display an image of a graph with a multiline y-axis label
 >> echo 'set t png; set o "i.png"; set yl "A\\$\\backslash\\$nVal"; plot x**2' | gnuplot; feh i.png

 * plot a graph of sin(x) setting the text of the x-axis and y-axis labels
 >> set xlabel "Angle, \\$\\backslash\\$n in degrees"; set ylabel "sin"; plot sin(x)

 * plot a graph from the shell of sin(x) with x-axis and y-axis labels
 >> echo 'se xl "Angle\\$\\backslash\\$n(deg)"; se yl "sin"; p sin(x)/cos(x)' | gnuplot -persist

 * plot a graph from the shell of sin(x) with x-axis and y-axis labels
 >> echo 'set grid; se xl "Angle\\$\\backslash\\$n(deg)"; p sin(x)/cos(x)'|gnuplot -persist

AXIS LABEL FONT AND SIZE ....

 * get help for setting the xlabels
 >> help set xl

 * show some help for setting the font for the label
 >> echo 'help set font' | gnuplot

 * show the current font path
 >> echo 'show fontpath' | gnuplot

 * set the font for the vertical axis label to Courier, size 14 points
 >> set ylabel font "courier,14"

 * create a y-axis label 'range' in courier font, size 14 points 
 >> echo 'set yl "Range" font "courier,16"; p sin(2*x)' | gnuplot -persist

 * create a y-axis label 'range' in size 18 points in the default font
 >> echo 'set yl "range" font ",18"; plot x**2' | gnuplot -persist

 * make a pink 18 point y-axis label 'val' in the default font
 >> echo 'set yl "val" font ",18" tc lt 4; plot x**2' | gnuplot -persist

 * make a pink 18 pnt y label 'val' rotated by 30 degrees anti-clockwise
 >> echo 'se yl "val" font ",18" tc lt 4 rot by 30;p x**2'|gnuplot -persist
 >> echo 'set yl "val" font ",18" tc lt 4 rotate by 30;p x**2' | gnuplot -persist

 * set the font for the horizontal axis label to Courier,20
 >> set xl "values" font "courier, 20"; plot x**2

 * set the horizontal axis label to the colour specified by 'linetype 4' 
 >> set xlabel textcolor lt 4 \\#\\#(but what colour is lt 4? you ask)
 >> set xlabel tc lt 4 \\#\\#(the same)
 >> se xl tc lt 4 \\#\\#(the same again)

ROTATING THE AXIS LABEL ....

 This isnt working for me

 * rotate the label ?
 >> echo 'set xlabel "Date" rotate by -45; plot x**3' | gnuplot -persist

 * make a pink 18point, label 'val' rotated by 30 degrees anti-clockwise
 >> echo 'se yl "val" font ",18" tc lt 4 rot by 30;p x**2' | gnuplot -persist
 >> echo 'set yl "val" font ",18" tc lt 4 rotate by 30;p x**2' | gnuplot -persist

MOVING THE AXIS LABEL ....

 * move the x axis label 1 character width to the left
 >> set xlabel offset -1,0

CUSTOMIZING THE AXIS LABEL ....

 * make a yellow 15 point horizontal label 'hello' in helvetica font
 >> set xlabel "hello" font "helvetica" textcolor lt 6
 >> set xlabel "hello" font "helvetica" tc lt 6
 >> echo 'se xl "Hello" font "helvetica,15" tc lt 6; p x**2' | gnuplot -persist

GRAPH SIZE AND SCALE

 * make the graph an exact square (regardless of value ranges
 >> set size square \\#\\#(only available in modern versions of gnuplot)

 * scale the graph so that the y (vertical) axis is twice as long as the x-axis
 >> set size ratio 2

 * scale the graph so that the x (horizontal) axis is twice as long as the y-axis
 >> set size ratio 0.5 
 
 * scale y-axis by 2, retain x-axis size
 >> set size ratio square 1,2 

GRIDS

 * plot a sin curve over a grid of dotted lines (grid lines at each value 'tic')
 ::gnuplot>> set grid; plot sin(x)

 * remove a value grid from a plotted graph
 >> unset grid; replot;
 >> set nogrid; replot; \\#\\#(older versions of gnuplot)

THE VALUE RANGES

 * plot only data from 0.5 to 10 on the x-axis and 30 to 48 on the y-axis
 >> set xrange [0.5:10]; set yrange [30:48]; plot 'data.txt' 
 >> plot 'data.txt' [0.5:10][30:48] \\#\\#(this is the same)

 * plot data using using an x-range of 0 to the highest x value 
 >> set xrange [0:]; plot 'data.txt' \\#\\#(the horizontal axis starts at 0)

 * reset the value ranges previously set with 'set xrange' or 'set yrange'
 >> reset \\#\\#(the value ranges revert to the defaults)

YRANGE ....

 On a two dimension graph (or chart) the yrange in the vertical 
 range. By default when plotting "bar-charts" (also called "histograms")
 gnuplot uses the maximum value as the upper y-range, which in my
 opinion is unpleasant.

 * plot a graph with the default xrange, and y-range -20 to 20
 >> echo "plot [][-20:20] sin(x),cos(x),tan(x)" | gnuplot -persist
 
 * plot a graph setting the yrange explicitly to -20: 20
 >> echo "set yrange [-20:20]; plot sin(x),cos(x),tan(x)"|gnuplot -persist

 yrange can be abreviated to 'yr'

TICS
 
 'Tics' are those small little lines which 'mark' or are perpendicular
 to the axis (either horizontal or vertical). These tics are supposed
 to indicated value points or ranges. I think it should be spelt 
 'tick' but in gnuplot its spelt 'tic'.

 * view help for all the options for changing the x-axis value tics
 >> help set xtics

 * show information about all options currently set for the ytics
 >> show ytics

 * show the vertical (y-axis) tics outside of the axis line
 >> set ytics out \\#\\#(this affects the 'mirrored' opposite tics as well)

 * plot a curve with no 'tics' or value labels on the horizontal axis
 >> unset xtics; plot sin(x)

 * display vertical tics at intervals of 2 (by value)
 >> set ytics 2

 * display horizontal tics only starting at 50 with interval 100
 >> set xtics 50,100 \\#\\#(values outside this range are still plotted)

 * set x (horizontal) tics at the values 1, 2, 4, ... 1024
 >> set xtics (1,2,4,8,16,32,64,128,256,512,1024)

 * set y (vertical) tics at the values 1, 11, and 21
 >> set ytics (1,11,21)

MINOR TICS ....

 Minor tics are the even smaller little markes which occur on the
 horizontal and vertical axis

 * display one minor tic halfway between each major tic
 >> set mxtics 2

 * make the minor and major tics the same length
 >> set ticscale 1 1

TIC LABELS

 * plot a paraboloa with the x-axis labels rotated clockwise by -45 degrees
 >> set xtics rotate by -45; plot x**2

 * rotate the tic labels by 90 degrees
 >> set xtics rotate

 * plot a sin curve with only 3 x-axis value tics, on a grid
 >> set xtics ("0" 0, "90" pi/2, "-90" -pi/2); set grid; plot sin(x)
 \\#\\#(the grid only has 3 vertical lines, since there are only 3 x-axis tics)

 * set the value tics for the x-axis (format: "label" value [level])
 >> set xtics ("0" 0, "90" pi/2, "-90" -pi/2, "" pi/4 1, "" -pi/4 1, "" 3*pi/4 1, "" -3*pi/4 1)

 * explicit 'tic' examples
 --------------------------
 set xtics ("low" 0, "medium" 50, "high" 100)
 set ytics ("bottom" 0, "" 10 1, "top" 20)
 ,,,

TEXT TICK LABELS ....

 The tic label is the text which sits just next to the little tick
 mark on the vertical or horizontal axis. These labels can be 
 customized in gnuplot in many ways.

 * explicitly set three tic text labels at the values 0, 50 and 100)
 >> set xtics ("low" 0, "medium" 50, "high" 100)

 * dont put tics on the oposite side to the main y-axis (vertical axis)
 \\$>> set ytics nomirror \\#\\#(there are no tics but the oposite box-line stays)

 * display 3 tics on the vertical axis with no tic labels 
 >> du -s \\$\\verb|~|/*>j;echo 'set xtics rot by -45; set ytics ("" 0, "" 10, "" 20); p "j" u 1:xticl(2)' | gnuplot -persist

 * display 3 tics on the vertical axis with no tick labels (no text at the tick)
 >> du -s \\$\\verb|~|/*>j;echo 'set ytics ("" 0, "" 10, "" 20);p 'j' u yticl(2):1' | gnuplot -persist

 * add a tic and label 'Pi' on the x axis without affecting the default tics
 >> set xtics add ("Pi" 3.14159)

 * make tics on the y-axis 0,.5,1,1.5...10 and added one label 'Pi' at 3.141 
 >> set ytics 0,.5,10; set ytics add ("Pi" 3.141)

TIC INTERVALS ....

 * display the vertical tics at value intervals of 5
 >> set ytics 5 \\#\\#(this places tics at ... -10, -5, 0, 5, 10 etc)

 * display the x-tics starting at value 0, ending at 10 with an interval 0.5
 >> set xtics 0,0.5,10 \\#\\#(this show values 0, 0.5, 1, 1.5 ... 9.5, 10)

THE DATA PLOTTING STYLE

 Strangely theres no simple 'pie' chart in gnuplot


\title{} 
\author{bumble.sourceforge.net} 
\maketitle 
\tableofcontents data plotting styles
 .. points - each value a point or a cross or a box etc
 .. histogram - the usual bar graph
 .. lines - a straight line from each data value to the next
 .. linespoints - a line with points to indicate values 
 .. steps - looks like a city skyline
 .. boxes - these look like a histogram and are normally contiguous 
 .. errorbars - a vertical line showing an error range for each datapoint
 .. impulses - lines which go from the axis to the value point
 .. and others ...
 ..

 * set the style of data plotting to 'histogram'
 >> set style data histogram

 * histograms of disk usage of the current folder, labels rotated
 ----------------------------------------------------------------
 du -s * > j; 
 echo '
 set style data hist; 
 set xtics rot by -60; 
 plot "j" using 1:xticlabels(2)' | gnuplot -persist
 ,,,

 Histograms are not normally contiguous

 * histograms of 1st 20 results of disk usage of the current folder, 
 * with the labels rotated by 60 degrees
 >> du -s * > j; echo 'set style data boxes; set xtics rot by -60; plot [0:20] "j" using 1:xticlabels(2)' | gnuplot -persist

GETTING HELP ....

 * view a list of the available plotting styles
 >> plot x with

 * view help for different curve plotting styles
 >> echo help with | gnuplot \\#\\#(lots of examples)
 >> echo help plot with | gnuplot \\#\\#(the same)
 >> help plotting styles \\#\\#(gnuplot version >= 4.0)

 * show the current setting for what style of data plotting
 >> show style data

 * see a list of valid data plotting styles
 >> set style data

PLOTTING WITH POINTS ....

 * plot a parabola with points
 >> plot x**2 w p
 >> plot x**2 with points \\#\\#(the same)
 >> set style data points; plot x**2 \\#\\#(the same, but persistent)
 >> set style data p; plot x**2 \\#\\#(the same, again)

 * plot the line 'y=x' with points (crosses) which are 4 times the normal size 
 >> plot x w points pointsize 4 \\#\\#(the default point seems to be a cross) 
 >> plot x w points ps 4 \\#\\#(the same) 
 >> plot x w p ps 4 \\#\\#(the same, again) 

 * plot a parabola with a line with 'x'es at value points
 >> plot x**2 with linespoints
 >> plot x**2 w linespoints \\#\\#(the same)
 >> plot x**2 w lp \\#\\#(the same again, nice and terse)
 >> set style data linespoints; plot x**2 \\#\\#(the same, persistent)

 * plot a parabola with a line with little boxes at value points
 >> plot x**2 with linespoints pointtype 5
 >> plot x**2 w lp pt 5 \\#\\#(the same, not so verbose)

 * plot a parabola with 'boxes' or contiguous vertical bars (a histogram)
 >> plot x**2 w boxes \\#\\#(this looks like a mathematical bar-chart)
 >> plot x**2 with boxes \\#\\#(the same)

 * plot a parabola with purple bars
 >> plot x**2 with boxes lt 4 
 >> plot x**2 with boxes linetype 4 \\#\\#(the same)

 * plot a sin and a cos curve on one field with different curve types
 --------------------------------------------------------------------
 echo "plot sin(x) w linespoints pointtype 5, cos(x) w boxes" | \\$\\backslash\\$
 gnuplot -persist
 ,,,


\title{} 
\author{bumble.sourceforge.net} 
\maketitle 
\tableofcontents linespoints styles
 .. linespoints pointtype 5 - like a beaded necklace, boxes on a line
 ..


\title{} 
\author{bumble.sourceforge.net} 
\maketitle 
\tableofcontents the linespoints pointtype values
 .. 4 - empty boxes
 .. 5 - filled boxes
 ..

IMPULSES ....

 * plot disk use data with impulses
 >> echo "plot '-' using 1:xticl(2) with impulses; \\$(du -s \\$\\verb|~|/*)" | gnuplot -persist
 
THE GRAPH LEGEND

 The 'legend' or 'key' of the plot describes what each curve (or dataset) 
 actually means and by default is in the top right corner. In gnuplot
 the legend is called the 'key'

 >> echo help set key | gnuplot

 * put a box around the graph legend and place it in the top left corner
 >> echo "set key top left; set key box; plot x**0.5;" | gnuplot -persist

 * places the key in the bottom left corner, left-justified text
 * with it a title, and draws a box around it in linetype 3:
 -----------------------------------------------------------
 echo "
 set key left bottom Left title 'Legend' box 3
 splot x*x-y*y" | gnuplot -persist
 ,,,

SIDE BY SIDE GRAPHS

 * side by side
 --------------------------------
 \\# multiplot mode
 \\# This sets up bounding boxes and may be required on some terminals
 set size 1,1
 set origin 0,0

 \\# Done interactively, this takes gnuplot into multiplot mode
 \\# and brings up a new prompt ("multiplot >" instead of "gnuplot >")
 set multiplot

 \\# plot the first graph so that it takes a quarter of the screen
 set size 0.5,0.5
 set origin 0,0.5
 plot sin(x)

 \\# plot the second graph so that it takes a quarter of the screen
 set size 0.5,0.5
 set origin 0,0
 plot 1/sin(x)
 unset multiplot
 reset
 ,,,


DRAWING ARROWS

 * draw some arrows 
 >> set arrow from 1,2 to 4,8.4 nohead lt -1 lw 1.2

PLOTTING DATA

 The process of plotting data with gnuplot involves taking a text file
 which has 'fields' separated by a 'separator' character or characters
 (usually a space or tab characters) and turning that data into a graph or
 chart. Often this chart would be a 'histogram' (that is a 'bar-chart),
 but other forms are possible.

 @@ \url{http://www.linuxquestions.org/questions/linux-software-2/gnuplot-how-to-label-x-axis-with-strings-from-data-file-462635/}
 How to use a field to supply the x-tic labels (horizontal axis value labels)
 
 The word 'field' and 'column' are used interchangably.

DATA SOURCES ....

 The data which you which to visualise in a graph can come from a 
 variety of sources. It is also possible to take it from the 
 'standard in' of the system, using the usual piping mechanisms.
 
 * plot disk use data with impulses
 ----------------------------------
 echo "
 set xtics rotate by -45
 plot '-' using 1:xticl(2) with impulses; 
 \\$(du -s \\$\\verb|~|/*|head -10)" | gnuplot -persist
 ,,,

 * prepare some data about last logon times using tr, cut etc
 >> last reboot|grep reboot|tr -s ' '|cut -d' ' -f5-6|tr ' ' .|uniq

 Using 'tr' and 'cut' in tandem like this allows us to extract
 fields from the text data (since cut can only handle field delimiters
 of one character). It would be possible to use awk instead but I 
 like the simplicity of this.

THE GOTCHAS ....
 
 * file names must be enclosed in quote characters (unless its the shell)
 >> plot data.txt \\#\\#(No! doesnt work)
 >> plot 'data.txt' \\#\\#(correct)

 * the datafile should only contain numbers (or use 'xticlabels' etc)
 ---------------------------------------------------------------------
 datafile:
 italy 2
 spain 5
 ...
 >> plot 'data.txt' \\#\\#(this produces an error because of the text 'italy' etc)
 ,,,

 * if the data file contains text (not numbers), use 'using' to avoid that field
 >> plot 'data.txt' using 2:3 \\#\\#(the first field may contain text)

BASIC DATA PLOTTING ....

 * list the contents of the text data file 'data.txt'
 >> !less data.txt

 * plot data using column 1 for the x-axis and column 2 for the y-axis
 >> plot 'data.txt' using 1:2 \\#\\#(data is plotted with little crosses '+') 

 * plot data using field 3 for the x-axis and field 2 for the y-axis
 >> plot 'data.txt' using 3:2 

 * plot data which is entered at the terminal, (useful for experimenting)
 --------------------------------------------
 plot '-'
 1 10
 2 20
 3 5
 ,,,

 * plot disk usage without making a temporary file 
 -------------------------------------------------
 (echo "
 set xtics rot; 
 plot '-' using 1:xticlabels(2)"; 
 du -s \\$\\verb|~|/*) | gnuplot -persist
 ,,,

 * the same as above but more terse
 >> (echo "set xtic rot;plot '-' u 1:xticl(2)"; du -s \\$\\verb|~|/*)|gnuplot -persist

 * plot disk usage with lines using only the first 10 results 
 ------------------------------------------------------------
 (echo "
 set xtics rot by -60;
 plot [0:10] '-' using 1:xticlabels(2) with lines"; 
 du -s \\$\\verb|~|/*) | gnuplot -persist
 ,,,

 * plot disk usage with lines using only the first 10 results 
 ------------------------------------------------------------
 (echo "
 set terminal dumb 70 25
 set xtics rot by -60;
 plot [0:10] '-' using 1:xticlabels(2)"; 
 du -s \\$\\verb|~|/*) | gnuplot
 ,,,

 * do something 
 >> (echo "set xtics rotate by -45; plot using 1:xticlabels(2) '-' "; du -s \\$\\verb|~|/* ; ) | gnuplot -persist
 
PLOTTING DATA WITH VALUE RANGES ....

 The default data range is from the minimum value to the maximum + 1
 on both the x and y axes.

 * plot the data using a horizontal (x) range of 0 to 20 and the default y-range
 >> plot [0:20] 'data.txt' 
 >> set xrange [0:20]; plot 'data.txt' \\#\\#(the same, but persists)

 * plot field 2 vs field 3 using an x range of -10 to 10 and a y-range of -5 to 6
 >> plot [-10:10][-5:6] 'data.txt' using 2:3

 * plot column 2 vs 3 using the y value range of -5 to 5 and the default x range
 >> plot [][-5:5] 'data.txt' using 2:3
 >> set yrange [-5:5]; plot 'data.txt' using 2:3 \\#\\#(the same, but persists)
 
 * start the x and y value range at -10 to their respective defaults
 >> plot [-10:][-10:] 'data.txt' 

 * plot the data file 'data.txt' with the x (horizontal) range starting at 0
 >> use xrange [0:]; plot 'data.txt' \\#\\#(file can only contain numbers)
 >> plot [0:] 'data.txt' \\#\\#(the same)

PLOTTING TEXT VALUE DATA ....

 * plot direct from standard in
 >> (echo "set xtics rotate by -45;plot '-' using 1:xticlabels(2)"; du -s \\$\\verb|~|/*)|gnuplot -persist

 * plot some data as histograms
 ------------------------------
 (echo "
 set xtics rotate by -45
 set style histogram clustered gap 1; set boxwidth 1.5
 set style data histogram 
 plot [][0:15] '-' using 2:xticlabels(1)"; 
 echo "
 france 10
 italy 14
 spain 2
 england 5")|gnuplot -persist
 ,,,

 * plot 'list.txt' using field 2 for the values and taking x-axis 
 * labels from the first column of the datafile
 >> plot "list.txt" using 2:xticlabels(1) \\#\\#(gnuplot version >= 4.1)
 >> plot "list.txt" u 2:xticlabels(1) \\#\\#(the same) 

 * plot some text versus number data from the bash command line
 >> echo 'plot "list.txt" using 2:xticlabels(1)' | gnuplot -persist

 * plot label vs value data using boxes instead of little crosses
 >> plot 'data.txt' using 2:xticlabels(1) with boxes \\#\\#(almost like a barchart)
 >> plot 'data.txt' using 2:xticlabels(1) w boxes \\#\\#(the same)
 >> plot 'data.txt' u 2:xticlabels(1) w b \\#\\#(the same, but better)

 * plot text vs value data using lines (a crooked line)
 >> plot 'data.txt' u 2:xticlabels(1) w l 
 >> plot 'data.txt' using 2:xticlabels(1) with lines \\#\\#(the same)

 By default the labels are printed horizontally

 * plot home disk use data with labels from the 2nd column, rotated 45 degrees clockwise
 >> du -s \\$\\verb|~|/* > j.txt; echo 'set xtics rotate by -45; plot "j.txt" using 1:xticlabels(2)' | gnuplot -persist
 
 * plot the first 10 results of diskusage 
 >> echo "set xtic rot by -45; plot [0:10] '-' using 1:xticl(2); \\$(du -s \\$\\verb|~|/*)"|gnuplot -persist
 
 * a more concise and cryptic version of the above
 >> (echo 'set xtic rot by -45; p "j" u 1:xticl(2)';du -s \\$\\verb|~|/*) | gnuplot -persist
 * use lines starting at the axis going to the value to graph the data
 >> plot "data.txt" u 2:xticlabels(1) w imp

 * define a new thick linestyle and use for a fake barchart 
 ----------------------------------------------------------
 \\#set linestyle 1 lt 1 lw 50; 
 \\#set linestyle 1 linetype 1 linewidth 50 \\#\\#(the same)
 \\# modern versions
 echo "
 set style line 1 linetype 1 linewidth 50 
 plot '-' u 2:xticlabels(1) with impulses linestyle 1; 
 \\$(du -s *)" | gnuplot -persist
 ,,,

 >> plot 'd.txt' u 2:xticlabels(1) w imp ls 1 \\#\\#(the same)\\_

ERROR BARS ....
 
 * plot data which contains an 'error margin' in the 3rd column
 --------------------------------------------------------------
 plot "test.dat" using 1:2:3 with yerrorbars
 example data:
 1.0 1.2 0.2
 2.0 1.8 0.3
 3.0 1.6 0.2
 ,,,

BAR CHARTS
 
 @@ \url{http://t16web.lanl.gov/Kawano/gnuplot/plot5-e.html}
 examples of drawing barcharts with 'impulses'

 The simplest way to plot a bar-chart or histogram is to use the
 'histograms' plotting style (after 'with') The 'histograms' is by default
 separated and the 'boxes' are by default contiguous.

BAR CHARTS WITH HISTOGRAMS ....


\title{} 
\author{bumble.sourceforge.net} 
\maketitle 
\tableofcontents histogram styles
 .. set style histogram clustered - put the bar right over the tic 
 .. set style histogram errorbars \{gap <gapsize>\} \{<linewidth>\}
 .. set style histogram rowstacked
 .. set style histogram columnstacked
 ..

 If the bars on the bar-chart are filled with colour then
 the tics on the axis are no longer visible.

 * view help about using the 'histograms' plotting style
 >> help histograms

 * see help about fillstyles for use with boxes and histograms
 >> help set style fill

 * set the gap between bars to be equal to the width of the bar 
 >> set style histogram clustered gap 1 

 The histogram bar is centered over the tick

 * narrow the gap between bars by increasing the boxwidth
 >> set style histogram clustered gap 1; set boxwidth 1.5 
 >> se sty histog clustered gap 1; set boxwidth 1.5 \\#\\#(abbreviated)

 * plot data using filled bars with the bars closer together
 -----------------------------------------------------------
 (echo "
 set style histogram clustered gap 1; 
 set style fill solid
 set boxwidth 1.7; set yrange [0:13]
 set xtics rotate by -45; 
 plot '-' using 2:xticlabels(1) with histograms";
 echo -e "
 bill 10\\$\\backslash\\$nbob 12\\$\\backslash\\$njack 3\\$\\backslash\\$njuan 6") | gnuplot -persist
 ,,,

 * plot data using unfilled histograms 
 -------------------------
 (echo "
 set style histogram clustered gap 1; 
 set xtics rotate by -45; 
 plot '-' using 1:xticlabels(2) with histograms";
 du -s \\$\\verb|~|/*|head -15) | gnuplot -persist
 ,,,

 The fill patterns depend on the type of output wanted

 * histograms filled with a check 
 --------------------------------
 (echo "
 set style histogram clustered gap 1
 set style fill pattern 1; 
 set xtics rotate by -45;
 plot '-' using 1:xticlabels(2) with histograms"; 
 du -s \\$\\verb|~|/* | head -15) | gnuplot -persist
 ,,,
 
 * histograms filled with slanted lines widely spaced
 ----------------------------------------------------
 (echo "
 set style histogram clustered gap 1
 set style fill pattern 4; 
 set xtics rotate by -45;
 plot '-' using 1:xticlabels(2) with histograms"; 
 du -s \\$\\verb|~|/*|head -15) | gnuplot -persist
 ,,,

 * the same as previously but create an image file o.png 
 -------------------------------------------------------
 (echo "set terminal png; set output 'o.png';
 set style fill pattern 4; 
 set xtics rotate by -45;
 plot '-' using 1:xticlabels(2) with histograms"; 
 du -s \\$\\verb|~|/*|head -15) | gnuplot; display o.png
 ,,,

 >> set terminal png; set output "out.png"; plot sin(x)

 * histograms filled with slanted lines narrowly spaced
 ------------------------------------------------------
 (echo "set style fill pattern 6; 
 set xtics rotate by -45; 
 plot '-' using 1:xticlabels(2) with histograms"; 
 du -s \\$\\verb|~|/* | head -15) | gnuplot -persist
 ,,,

 * make a narrower gap between each bar of the histogram
 -------------------------------------------------------
 (echo "set style histogram clustered gap 1; 
 set boxwidth 1.5; set xtics rotate by -45; 
 plot '-' using 1:xticlabels(2) with histograms"; 
 du -s \\$\\verb|~|/* | head -15) | gnuplot -persist
 ,,,

 * set the bars to be filled with solid colour
 >> set style fill solid 2; plot 'data.txt' u 1:2 w histograms

 * plot data from standard in, solid red bars
 --------------------------------------------
 (echo "
 set style histogram clustered gap 1
 set style fill solid 1
 set xtics rotate by -45
 plot '-' using 1:xticlabels(2) with histograms"; 
 du -s \\$\\verb|~|/*|head -15) | gnuplot -persist
 ,,,

 * solid but pale red bars (intensity 0.3) close together
 --------------------------------------------------------
 (echo "set style fill solid 0.3;
 set style histogram clustered gap 1; 
 set boxwidth 1.5; set xtics rotate by -45; 
 plot '-' using 1:xticlabels(2) with histograms"; 
 du -s \\$\\verb|~|/* | head -15) | gnuplot -persist
 ,,,

 * solid but pale red bars (intensity 0.3) close together
 --------------------------------------------------------
 (echo "set style fill solid 0.3;
 set style fill border linetype 2;
 set style histogram clustered gap 1; 
 set boxwidth 1.5; set xtics rotate by -45; 
 plot '-' using 1:xticlabels(2) with histograms"; 
 du -s \\$\\verb|~|/* | head -15) | gnuplot -persist
 ,,,

 * pale red bars, x-labels rotated
 ---------------------------------
 (echo "
 set style fill solid 0.3;
 set xtics rotate by -45; 
 plot '-' using 1:xticlabels(2) with histograms"; 
 du -s \\$\\verb|~|/* | head -15) | gnuplot -persist
 ,,,

 * fill each bar with colour half the intensity of the border colour
 >> set style fill solid 0.5; plot 'data.txt' u 1:2 w histograms

 * fill each bar with 'pastely' (faint) colour without any borders on the bars
 >> set style fill solid 0.5 noborder; plot 'data.txt' u 1:2 w histograms

 * plot column 1 vs column 2 of 'data.txt' with separated 'bars'
 >> plot 'data.txt' using 1:2 with histograms
 >> plot 'data.txt' u 1:2 w histo \\#\\#(the same)
 >> set style data histograms; plot 'data' using 1:2 \\#\\#(the same)

 * use labels with multiple columns
 >> plot 'file.dat' using 2, '' using 4, '' using 6:xticlabels()

 * plot text vs number data as a barchart with a y-axis range starting at 0 
 >> plot [][0:] 'data.txt' u 2:xticlabels(1) w histograms
 
 * plot col 2, col 3 as histograms clustered around the labels of field 1
 >> plot 'data.txt' u 2:xticlabels(1) w histog, '' u 3 w histog

BAR CHARTS USING BOXES ....

 * plot a barchart with filled boxes (fill intensity 0.7)
 >> plot "test.dat" usi 1:2 w boxes fs solid 0.7
 >> plot "test.dat" using 1:2 w boxes fillstyle solid 0.7 \\#\\#(the same)

 * create a barchart with boxes taking up half the possible space 
 >> set boxwidth 0.5; plot 'test.dat' using 1:2 with boxes \\#\\#(boxes separated)
 >> set boxwidth 0.5; plot 'test.dat' u 1:2 w boxes \\#\\#(the same)
 >> set boxw 0.5; plot 'data.txt' u 1:2 w boxes \\#\\#(the same)

 * make thin filled rectangles for the bar chart
 >> set boxw 0.2; plot 'data.txt' u 1:2 w boxes fs solid 0.7

BAR CHARTS WITH IMPULSES ....

 * use lines from the axis to the value ('impulses') for graphing the data
 >> plot "data.txt" u 2:xticlabels(1) w imp
 >> plot "data.txt" using 2:xticlabels(1) with impulses \\#\\#(the same)
 
THE DATAFILE FORMAT
 
 The text datafile normally consists of rows of data where each row consists of
 a set of numbers separated by space or tab characters.

 If a line begins with '\\#' is normally ignored

 * set the character which indicates that data is missing in the data file.
 \\$>> set datafile missing "-"

 * show what character currently indicates missing data in the text file
 \\$>> show datafile missing \\#\\#(there is no default missing data character)

 * set the character which separates fields in the datafile to a comma ','
 >> set datafile separator ','

PLOTTING ONLY SOME OF THE DATA ....

 * plot only every second line from the text data file 'test.dat'
 >> plot "test.dat" every 2 

 * plot only every second data block from the data file 
 >> plot "test.dat" every :2 \\#\\#(the datablocks are separated by blank lines)

 * more examples
 ---------------

 every I:J:K:L:M:N 
 I Line increment
 J Data block increment
 K The first line
 L The first data block
 M The last line
 N The last data block
 every 2 plot every 2 line
 every ::3 plot from the 3-rd lines
 every ::3::5 plot from the 3-rd to 5-th lines
 every ::0::0 plot the first line only
 every 2::::6 plot the 1,3,5,7-th lines
 every :2 plot every 2 data block
 every :::5::8 plot from 5-th to 8-th data blocks 
 ,,,

 * use a shell command to select or modify data to plot
 ------------------------------------------------------

 >> plot "< head -10 test.dat" using 1:2 with lines
 >> plot "< tail -3 test.dat" using 1:2 with lines
 >> plot "< head -5 test.dat" using 1:2 with lines,\\$\\backslash\\$
 > plot "< tail -5 test.dat" using 1:2 with points
 ,,,

CALCULATING THE DATA ....

 * plot data from 'data.txt' doing arithmetic on each column
 >> plot 'table.dat' using (\\$3/\\$1):(\\$2*134.44)

 * plot field 1 versus the square root of field 2
 >> plot "test.dat" using 1:(sqrt(\\$2)) with points

PLOTTING TIME DATA ....

 Plotting time data may be somewhat tricky, since it is necessary to
 inform gnuplot of the format of the time stamp contained in the 
 data file

 * display the gnuplot help for the 'timefmt' setting
 >> echo help set timefmt | gnuplot

 >> help time/data
 * the data file 'data.txt'
 ---------------
 10-Jun-04 90.23
 9-Jun-04 89.90
 8-Jun-04 88.64
 7-Jun-04 88.75
 4-Jun-04 87.95
 3-Jun-04 87.85
 ,,,

 * indicate that the x-axis data is time
 >> set xdata time 

 * The dates in the file look like '10-Jun-04'
 >> set timefmt "\\%d-\\%b-\\%y" 

 * On the x-axis, we want tics like Jun 10
 >> set format x "\\%b \\%d" 

 >> plot ["31-May-04":"11-Jun-04"] 'data.txt' using 1:2 with linespoints 

 * a clustered histogram with time data
 --------------------------------------
 10-Jun-04 90.23 90.75 89.89 90.46
 9-Jun-04 89.90 90.55 89.81 90.09
 8-Jun-04 88.64 90.50 88.40 90.04
 7-Jun-04 88.75 88.99 88.01 88.64
 4-Jun-04 87.95 88.49 87.50 87.56
 3-Jun-04 87.85 88.10 87.35 87.35
 ,,,

MULTIPLE GRAPHS ON ONE FIELD
 
 * plot the curves x-squard and x-cubed on the same grid (field)
 >> echo 'plot x**2, x**3' | gnuplot -persist
 
 * plot fractional powers of 'x' using bash brace expansion from x=0 to 4
 >> echo plot [0:4] "x**2."\{1..7\}"," "x**2.8" | gnuplot -persist

 * plot fractional powers of 'x' using bash brace expansion from x=0 to 4
 >> echo plot [0:4] "x**2."\{1..7\}"," "x**2.8" | gnuplot -persist
 
 * plot a long polynomial using bash brace expansion
 >> echo plot "x**"\{9..1\}" +" 1 | gnuplot -persist

OUTPUT FORMATS

 * view all possible output formats which gnuplot can produce 
 >> echo set terminal | gnuplot 
 >> echo help set terminal | gnuplot 

 * create a 'png' image file 'out.png' with the graph of a sin curve
 >> set terminal png; set output "out.png"; plot sin(x)

 * plot graphs to a linux window (using wxWidgets tool kit)
 >> set terminal wxt


\title{} 
\author{bumble.sourceforge.net} 
\maketitle 
\tableofcontents some important output formats for gnuplot
 .. svg - scalable vector graphics (if you want to resize alot)
 .. png - image format good for web-pages
 .. jpg - image also good for web-pages
 .. x11 - unix/linux window
 .. wxt - linux window
 .. gif - good for animations
 ..

 * create a png image 'o.png' graph of a sin curve in the current folder
 -----------------------------------------------------------------------
 echo " 
 set terminal png; 
 set output 'o.png'; 
 splot sin(x**2 + y**2)/(x**2 + y**2)" | gnuplot
 display o.png
 ,,,

 * create a jpeg image 'o.jpg' a hyperbolic tangent function 
 -----------------------------------------------------------
 echo "
 set terminal jpeg
 set output 'o.jpg'
 set grid
 plot tanh(x)" | gnuplot
 display o.jpg
 ,,,

 * create a jpeg image 'o.jpg' of a polynomial with a value grid 
 ---------------------------------------------------------------
 echo "
 set terminal jpeg
 set output 'o.jpg'
 set grid; plot x**3+x**2+x+1" | gnuplot
 display o.jpg
 ,,,

 * create postscript file 'o.eps' graph of a sin curve
 >> echo "set terminal eps; set output 'o.eps'; plot sin(x)" | gnuplot
 
 You could include this in a report using the enscript tool to convert
 a text document to pdf or postscript format

SVG OUTPUTS ....

 Svg stands for scalable vector graphics and is an important image
 format because it stores the image as drawing 'instructions' in a 
 plain text (xml) format. This means that it is possible to use the 
 normal unix toolset to pre- or post-process svg images.

 * display the gnuplot help for the 'svg' output format
 >> echo help set terminal svg | gnuplot

ASCII PLOTTINGS ....

 By setting the 'terminal' type to 'dumb' it is possible to produce
 a graph using only 'ascii' characters (normal letters numbers and 
 symbols). This may be useful for including in text documents.

 The 'persist' option to gnuplot is not necessary with the 'dumb'
 terminal because the graph is printed to 'standard out' (the screen)
 in anycase.

 * display the gnuplot help for the 'dumb' (ascii/text) output format
 >> echo help set terminal dumb | gnuplot

 * plot the graph 'sin(x)' as ascii text
 >> echo "set terminal dumb; plot x**2" | gnuplot 
 >> echo "se te du; p x**2" | gnuplot \\#\\#(the same)

 * plot a parabola in plain text, width 60 characters and height 30 chars
 >> echo "set terminal dumb 60 30; plot x**2" | gnuplot

 * plot an 'ascii' parabola, 70x20 characters with no values on the axes 
 -----------------------------------------------------------------------
 echo "
 unset tics
 set terminal dumb 70 20 
 plot x**2" | gnuplot
 ,,,

 * plot an 'ascii' sin curve, 70x20 characters, this looks wobbly
 >> echo "set term dumb 70 20; p sin(x)" | gnuplot 

 * plot an 'ascii' parabola, with a multiline title 
 --------------------------------------------------
 echo '
 set title "parabola\\$\\backslash\\$nx\\^2" 
 set terminal dumb 70 20 
 plot x**2' | gnuplot
 ,,,

VIM AND GNUPLOT

 It is possible to create some new commands and command mappings to
 automatically generate graphs from the lines in a text file (be it data or
 gnuplot commands)

 * a vim command to plot the current line (assuming it is a gnuplot command)
 >> .w !sed 's/\\^ *\\#//;s/ \\$\\backslash\\$\\#.*\\$//' | gnuplot -persist

 * a 'mapping' to plot the current line (as above)
 >> :map! ,gp .w !sed 's/\\^ *\\#//;s/ \\$\\backslash\\$\\#.*\\$//' | gnuplot -persist

 * a new vim command to plot the current line
 >> :command! Gp .w !sed 's/\\^ *\\#//;s/ \\$\\backslash\\$\\#.*\\$//' | gnuplot -persist
 
 * a vim command to plot the current line to the file 'o.jpg'
 >> :.w !sed 's/\\^ */set terminal jpeg; set output "o.jpg";/' | gnuplot

 * a command to plot to an image to a given file name in the image folder
 >> command! -nargs=1 Glti .w !sed 's/\\^ */set terminal jpeg; set output "image\\$\\backslash\\$/<args>.jpg";/' | gnuplot; gthumb image/<args>.jpg

 The new vim command above can be executed with
 >> :Glti test

USEFUL PLOTS 

 * plot number of logon times for the last few days
 --------------------------------------------------
 (echo "
 set xtic rot by -45; 
 set style data histogram; 
 plot [][0:] '-' using 1:xticlabels(2) ";
 last reboot|grep reboot|tr -s ' '|cut -d' ' -f5-7|\\$\\backslash\\$
 tr ' ' .|uniq -c) | gnuplot -persist
 ,,,

PLOTTING FROM THE COMMAND LINE

 * plot a sin curve, from x=-20 to 20, from a bash shell, leaving plot window open
 >> echo 'set xrange [-20:20]; plot sin(x)' | gnuplot -persist
 \\#\\#(gnuplot displays the graph in a separate window, which it leaves open)
 \\#\\#(-persist keeps the plot window open after gnuplot exits)

 * run gnuplot in batch mode with a command file
 >> echo 'set grid; plot sin(x)' > gp.txt; gnuplot -persist gp.txt
 >> echo 'set grid; plot sin(x)' > gp.txt; echo 'load gp.txt' | gnuplot -persist 

 * Quickly graph a list of numbers
 >> gnuplot -persist <(echo "plot \\$(<(sort -n listOfNumbers.txt)) with lines")

 * an example of creating a graph with gnuplot 
 >> \url{http://www.pixelbeat.org/docs/web/access\\_log/analyzing.html}

SURFACE OR 3D GRAPH PLOTTING

 The gnuplot command 'splot' is capable of plotting 'surfaces' and 
 other three-dimensional graphs

 * show some help for splot
 >> echo help splot | gnuplot
 >> echo help splot overview | gnuplot

 >> echo help isosamples | gnuplot


\title{} 
\author{bumble.sourceforge.net} 
\maketitle 
\tableofcontents important options
 .. set isosamples 20 - increases the number of 'contour' lines by 2
 .. set hidden - does not draw contour lines which are behind others
 ..

 * plot a surface with double the number of surface lines
 --------------------------------------------------------
 echo "
 set isosamples 20
 splot x*x-y*y" | gnuplot -persist
 ,,,

 * plot a surface with colored lines
 >> echo "splot x*x-y*y with line palette" | gnuplot -persist

 * plot a surface with colored surfaces 
 >> echo "splot x*x-y*y with pm3d" | gnuplot -persist

 * plot the same color surfaces but at different altitudes
 >> echo "splot x*x-y*y with pm3d, x*x+y*y with pm3d at t"|gnuplot -persist

 * plot a surface with doubled surface lines and x and y ranges -4 to 4
 --------------------------------------------------------
 echo "
 set isosamples 20
 splot [-4:4][-4:4] sin(x)-sin(y)" | gnuplot -persist
 ,,,

 The 'set hidden' option hides the contour lines on the surface 
 which are 'behind' other lines. This looks more natural (since one
 cant see something which is behind something else)

 * plot a surface with quadrupled surface lines and hidden lines hidden
 -------------------------------------------------------------------
 echo "
 set hidden
 set isosamples 40
 splot [-4:4][-4:4] sin(x)-sin(y)" | gnuplot -persist
 ,,,

MATHEMATICAL SURFACES ....

 This section concentrates on those renderings of mathematically
 functions of 2 variables such as z = x\\^2 + y\\^2
 
 * show no axis values, extra contour, and no 'hidden' lines 
 -----------------------------------------------------------
 echo "
 set hidden 
 set isosamples 40 
 splot x*x-y*y" | gnuplot -persist
 ,,,

ANIMATIONS OF GRAPHS

 By creating a large set of similar graphs with gnuplot we can
 then combine them into an animation using image magick 'convert'.
 This may be useful for showing trends etc.

 * create lots of similar graphs and create an animation, 10 frames/sec
 -------------------------------------------------------------------
 for i in \{1..30\}; do
 echo " 
 set terminal png; set output \\$\\backslash\\$"o\\$\{i\}.png\\$\\backslash\\$"
 set hidden; set isosamples 40;
 splot [-4:4][-4:4] 0.\\$\{i\}*sin(x)-sin(y)" | gnuplot; 
 done
 convert -delay 10 -size 200x200 o*.png -loop 0 -monitor test.gif
 ,,,

 * create an animation with a z range, 10 frames per second
 -------------------------------------------------------------------
 for i in \{1..50\}; do
 echo " 
 set terminal png; set output \\$\\backslash\\$"o\\$\{i\}.png\\$\\backslash\\$"
 set hidden; set isosamples 40;
 splot [-4:4][-4:4][-0.5:0.5] sin(x*x+y*y)/(x*x+y*y+\\$\{i\})" | gnuplot; 
 done
 convert -delay 10 -size 200x200 o*.png -loop 0 -monitor test.gif
 ,,,

 It may be a good idea to keep all the ranges fixed so that the 
 animation doesnt 'jump' around. Also the images need to be sorted 
 into a numerical order before supplying to converted.

 * create an animation of a coloured surface rising, 10 frames per second
 -------------------------------------------------------------------
 for i in \{1..50\}; do
 echo " 
 set terminal png; set output \\$\\backslash\\$"\\$\{i\}oo.png\\$\\backslash\\$"
 set hidden; set isosamples 40;
 splot [-6:6][-6:6][-20:60] x*x-y*y+(\\$i) with pm3d" | gnuplot; 
 done
 convert -delay 10 -size 200x200 \\$(echo *oo.png|tr ' ' '\\$\\backslash\\$n'|sort -n) -loop 0 -monitor test.gif
 ,,,

 * use the following to sort the images before converting to an animation
 >> echo *oo.png | tr ' ' '\\$\\backslash\\$n' | sort -n

 * a nice animation of a wavy 3d surface rising 
 ---------------------------------------------------------
 for i in \{1..30\}; do
 echo "
 set terminal png; set output \\$\\backslash\\$"\\$\{i\}xx.png\\$\\backslash\\$"
 set border 0; set hidden; unset tics; unset key
 set isosamples 80 
 splot [-4:4][-4:4] sin(x*x+y*y)/(x*x+y*y+\\$i/2) w line palette"|gnuplot
 done
 convert -delay 10 -size 200x200 \\$(echo *xx.png|tr ' ' '\\$\\backslash\\$n'|sort -n) -loop 0 -monitor test.gif
 ,,,

GRAPHS AS ART

 Apart from the use of graphs and charts for information purposes
 they may also have an artistic and aesthetic value. One technique it
 to place many curves on the same graph to achieve an artistic effect.

 * place an number of sin curves on a graph for artistic effect
 >> echo "p [][-20:20] sin(x),sin(x)+1,sin(x)+2,tan(x)"|gnuplot -persist

 * use bash brace expansion to create many curves with gnuplot 
 >> echo p "sin(x)+"\{0..20\}"," "tan(x) " | gnuplot -persist

 * use bash brace expansion to create many curves with gnuplot 
 >> echo p "sin(x)+"\{-15..15\}"," "tan(x) " | gnuplot -persist

 * plot a sin and a cos curve on one field with different curve types
 >> echo "unset tics; unset key;p sin(x),cos(x) w boxes"|gnuplot -persist

 * plot a sin and a cos curve on one field with different curve types
 >> echo "unset tics;unset key;p" " sin(x)+"\{0..5\}"," "cos(x) w boxes"|gnuplot -persist

ARTISTIC SURFACES ....

 By increasing the number of contour lines (with isosamples) and
 removing numbers from the axis and legends, the surface becomes
 more of an aesthetic artifact rather than an informational one.

 * show no axis values and extra contour lines for a surface
 -----------------------------------------------------------
 echo "
 unset tics; unset key
 set isosamples 40 
 splot x*x-y*y" | gnuplot -persist
 ,,,

 * show no axis values, extra contour, and no 'hidden' lines 
 -----------------------------------------------------------
 echo "
 set hidden; unset tics; unset key
 set isosamples 40 
 splot x*x-y*y" | gnuplot -persist
 ,,,

 * show no axis values, extra contour, and no 'hidden' lines 
 -----------------------------------------------------------
 echo "
 set hidden; unset tics; unset key
 set isosamples 40 
 splot x*x+y*y" | gnuplot -persist
 ,,,

 * remove all axes and values and plot with height colours
 ---------------------------------------------------------
 echo "
 set border 0; set hidden; unset tics; unset key
 set isosamples 80 
 splot [-4:4][-4:4] sin(x*x+y*y)/(x*x+y*y) with line palette" \\$\\backslash\\$
 | gnuplot -persist
 ,,,

SOME PEOPLE

 @@ Colin Kelley and Thomas Williams
 original developers of gnuplot in 1986
 @@ David Kotz 
 developed a version of gnuplot for tex output

DOCUMENT-NOTES:
 
 \\# this section contains information about the document and
 \\# will not normally be printed.

 \\# A small (16x16) icon image to identify the book
 document-icon: \texttt{/usr/share/icons/hicolor/22x22/apps/invest-applet.png}
 \\# A larger image to identify or illustrate the title page
 document-image:
 \\# what sort of document is this
 document-type: book
 \\# in what kind of state (good or bad) is this document 
 document-quality: useful
 \\# what work has been carried out on this
 document-history:
 @@ early 2010
 began this book. started experimenting with gnuplot
 @@ feb 2010 
 want to make some vim commands to compile gnuplot
 code fragments, as for latex

 \\# who wrote this
 authors: mjbishop at fastmail dot fm
 \\# a short description of the contents, possible used for doc lists
 short-description: making charts and graphs with gnuplot
 \\# A computer language which is contained in the document, if any
 code-language: gnuplot, bash
 \\# the script which will be used to produce html (a webpage)
 make-html: ./booktohtml.cgi
 \\# the script which will produce 'LaTeX' output (for printing, pdf etc)
 make-latex: ./booktolatex.cgi


 * Visualizing system performance data
 >> (echo "set terminal png;plot '-' u 1:2 t 'cpu' w linespoints;"; sudo vmstat 2 10 | awk 'NR > 2 \{print NR, \\$13\}') | gnuplot > plot.png
\end{document}
%end generated latex