featureful command line plotting of data in a Linux shell, made easy with eplot, a gnuplot wrapper. This version is modified slightly, per the instructions found here: http://stackoverflow.com/questions/123378/command-line-unix-ascii-based-charting-plotting-tool#answer-12868778. eplot in its original form can be found here: http://liris.cnrs.fr/…

eplot.rb

#!/usr/bin/ruby
# **************************************************************************
# ### modified based on:
# http://stackoverflow.com/questions/123378/command-line-unix-ascii-based-charting-plotting-tool
# ###
# eplot 
# Written by Christian Wolf
#
# eplot ("easy gnuplot") is a shell script which allows to pipe data easily 
# through gnuplot and create plots quickly, which can be saved in postscript, 
# PDF, PNG or EMF files. Plotting of multiple files into a single diagram is 
# supported.
# **************************************************************************
# This program is free software; you can redistribute it and/or modify  
# it under the terms of the GNU General Public License as published by  
# the Free Software Foundation; either version 2 of the License, or     
# (at your option) any later version.                                   
#                                                                         
# This program is distributed in the hope that it will be useful,       
# but WITHOUT ANY WARRANTY; without even the implied warranty of        
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         
# GNU General Public License for more details.                          
#                                                                         
# You should have received a copy of the GNU General Public License     
# along with this program; if not, write to the                         
# Free Software Foundation, Inc.,                                       
# 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.   
# **************************************************************************
# Changelog:
# 2.07 03.05.2007: -bugfix case where input file is empty
# 2.06 09.12.2005: -bugfix style not set when single plot from stdin
# 2.05 19.11.2005: -no dummy titles are displayed (tmp files etc.); bugfixes
# 2.04 13.11.2005: -Added -o option: specify the name of the output file
# 2.03 25.10.2005: -Bugfix: added some exception handling (File stuff)
# 2.02 25.10.2005: -Added -D option (dump created files)
#                  -Bugfix files containing dashes
# 2.01 22.10.2005: -Enabled color for postscript & PDF output
#                  -Changed option -w to option -l
#                  -Added -w option to change line width
#                  -Added -I option to change the order of style indices
#                  -Added -B option to create vertical bars
# 2.00 13.10.2005: -Port to the ruby programming language
# 1.07 27.09.2005: -Bugfix removed meaningless error message in some cases
# 1.06 03.07.2005: -Added -S: plotting multiple curves from a single column,
#                   the curves being separated by blank lines.
#                  -Fixed bug in the syntax validation code.
# 1.05 01.07.2005: -Fixed compatibility issue with older versions of gnuplot.
#                  -Fixed bug when options "-p -M" are provided
#                  -Added some argument checking
# 1.04 30.06.2005: -Bugfix option -M when data is piped
#                  -Improved -t option to make multiple titles possible
# 1.0  ??.??.2002: -Start of project, initial version written in 
#                   UNIX korn shell
# **************************************************************************

require 'tempfile'

# **************************************************************************
# CONFIGURATION

$Version="2.07 03.05.2007"
$TextViewer="cat"
$GnuPlot4OrNewer=true

# **************************************************************************
# VARIOUS CONSTANTS

$err="eplot: *** ERROR *** "
$barStyleIndex="20"

$help=<<MARKER_MESSAGE
Input data definition options:
 -m --mulfrmul   Multiple curves in a single diagram from different 
                 files. Each file contains a single column
 -M --mulfrsin   Multiple curves in a single diagram from a single file	
                 curves are in different columns
 -S --mulfrseq   Multiple curves in a single diagram from a single file
                 curves are in the same column sep. by a blank line
                 (the curve data must be separated by blank lines)
                 
Output file format options: 
 -P --png        Output to the PNG file foo.png 
 -p --postscript Output to the postscript file foo.ps 
 -a --pdf        Output to the pdf file foo.pdf
 -e --emf        Output to the emf file foo.emf
 -o <fname>      Specify the output filename
 
Output formatting options:
 -r <ranges>     set the range of x and y axis values
                 (e.g. -r [5:10][0:100]).
 -R <asp-ratio>  set the aspect ratio (1 for a square shaped diagram)
 -s <size>       set the size factor
 -l <type>       set the type of curve (lines,points,linespoints,...)
 -w <width>      set the line width (default: 1)
 -x <x-axis-opt> provide x-axis options
 -y <y-axis-opt> provide y-axis options
 -t <titles>     set the title(s) of the curve(s) (separated by @)
 -I <indices>    set the order of the line styles (separated by ,)
                 (e.g. -I "2,1,3,4,5")
                 
Miscellaneous opions:                 
 -B <pos>,<height> creates vertical bars (separated by @)
                 e.g. -B 100,0.8@200,0.8
 -D --dump       dump all used files as "eplot-dump-<nr>.dat"
 -h --help       print this help message
 -v --version    print version information
MARKER_MESSAGE

$licence=<<MARKER_MESSAGE
Written by Christian Wolf
License: GPL; this is free software. There is absolutely NO warranty!!
MARKER_MESSAGE

# ******************************************************************************
# Argument processing:
# The Option-Container class
# ******************************************************************************

class OptionController

	# --------------------------------------------------------------------------
	# ---- constructor
	def initialize(xargv)		
		@o={}
		@o["Files"]=[]
		@o["LineType"]="lines"
		@o["LineWidth"]="1"
		@o["DoPDF"]=false
		@o["MulFrMul"]=false
		@o["MulFrSin"]=false
		@o["MulFrSeq"]=false
		@o["DumpFiles"]=false
		@o["TitleString"]=""
		@o["Bars"]=""
		@o["StyleIndices"]="1,2,3,4,5,6,7,8,9,10,11,12"
		@o["Size"]=""
		@o["Ratio"]=""
		@o["Range"]=""
		@o["OutputFileDefault"]=""
		@o["OutputFileSpecified"]=""				
		
		i=0
		com=""
		while i<xargv.length
			opt=xargv[i]

			case opt			
			
				when /^-h$|^--help$/
					usage					
			
				when /^-v$|^--version$/ 
					$stderr.puts "eplot version "+$Version
					$stderr.puts $licence
					exit 0
			
				# ---- Do we create PNG output?
				when /^-P$|^--png$/
					com=com+"set terminal png;\n"
					@o["OutputFileDefault"]="foo.png"
			
				# ---- Do we create Postscript output?
				when /^-p$|^--postscript$/
					com=com+"set terminal postscript color;\n"
					@o["OutputFileDefault"]="foo.ps"
			
				# ---- Do we create EMF output?
				when /^-e$|^--emf$/
					com=com+"set terminal emf \"helvetica\";\n"
					@o["OutputFileDefault"]="foo.emf"
			
				# ---- Do we create PDF output? First we create postscript
				# ---- A conversion is done afterwards
				when /^-a$|^--acrobat$|--pdf$/
					com=com+"set terminal postscript color;\n"
					@o["DoPDF"]=true
					
				# ---- Specify a custom output file
				when /^-o$|^--output$/
					@o["OutputFileSpecified"]=checkOptArg(xargv,i)
					i=i+1
					
				# ---- Multiple curves in a single diagram from different files
				when /^-m$|^--mulfrmul$/
					@o["MulFrMul"]=true
				
				# ---- Multiple curves in a single diagram from a single file
				when /^-M$|^--mulfrsin$/
					@o["MulFrSin"]=true
				 
 				# ---- Multiple curves in a single diagram from a single column
				when /^-S$|^--mulfrsinseq$/
					@o["MulFrSeq"]=true
					
				# ---- the range
				when /^-r$|^--range$/					
					@o["Range"]=checkOptArg(xargv,i)+" "
					i=i+1
					
				# ---- the size
				when /^-s$|^--size$/					
					@o["Size"]=checkOptArg(xargv,i)
					i=i+1
					
				# ---- the aspect ratio
				when /^-R$|^--aspectratio$/					
					@o["Ratio"]=checkOptArg(xargv,i)
					i=i+1
					
				# ---- the line type
				when /^-l$|^--linetype$/					
					@o["LineType"]=checkOptArg(xargv,i)
					i=i+1					
					
				# ---- the line width
				when /^-w$|^--linewidth$/					
					@o["LineWidth"]=checkOptArg(xargv,i)
					i=i+1					
					
				# ---- the title string
				when /^-t$|^--title$/					
					@o["TitleString"]=checkOptArg(xargv,i)
					i=i+1
					
				# ---- the style indices
				when /^-I$|^--styleindices$/					
					@o["StyleIndices"]=checkOptArg(xargv,i)
					i=i+1
					
				# ---- the x-axis label
				when /^-x$|^--xlabel$/					
					com=com+"set xlabel \""+checkOptArg(xargv,i)+"\";\n"
					i=i+1
					
				# ---- the y-axis label
				when /^-y$|^--ylabel$/					
					com=com+"set ylabel \""+checkOptArg(xargv,i)+"\";\n"
					i=i+1
				
				# ---- the vertical bars
				when /^-B$|^--bars$/					
					@o["Bars"]=checkOptArg(xargv,i)
					i=i+1
					
				# ---- dump files
				when /^-D$|^--dump$/					
					@o["DumpFiles"]=true
					
				# ---- an unknown option
				when /^-/
					$stderr.printf "%sunknown option '%s'\n",$err,opt					
					exit 1
			
				# ---- The argument is not an option but a file
				else				
					@o["Files"].push(opt)
			end
			i=i+1
		end
				
		# ---- Configure the output filename. In the case of PDF
		# ---- we keep the default filename, since GNUplot does not do
		# ---- PDF, we translate afterwards
		if @o["DoPDF"]
			com=com+"set output \"foo.ps\";\n"
		else
			if @o["OutputFileSpecified"]!=""
				com=com+"set output \""+@o["OutputFileSpecified"]+"\";\n"
			else
				if @o["OutputFileDefault"]!=""
					com=com+"set output \""+@o["OutputFileDefault"]+"\";\n"
				end
			end
		end
		
		# ---- The size and ratio options are set in the same command,
		# ---- so do it here.
		if @o["Size"]!="" or @o["Ratio"]!=""
			com=com+"set size "
			com=com+"ratio "+@o["Ratio"]+" " if @o["Ratio"]!=""
			com=com+@o["Size"]+","+@o["Size"]+" " if @o["Size"]!=""
			com=com+";\n"
		end
		@o["MiscOptions"]=com
	end
	
	# --------------------------------------------------------------------------
	# ---- check for a valid option argument
	def checkOptArg(argv,i)
		if argv.length<i+2
			$stderr.printf "%soption '%s' needs an argument!\n",$err,argv[i]
			exit 1
		end
		if argv[i+1][0,1]=="-"
			$stderr.printf "%sinvalid argument '%s' to option '%s'!\n",$err,
				argv[i+1],argv[i]
			exit 1
		end
		return argv[i+1]
	end
		
	# --------------------------------------------------------------------------	
	# ---- writes the usage message
	def usage
		$stderr.printf "usage: %s [ options ]\n",$0
		$stderr.printf "\n%s\n",$help
		exit 0
	end

	# --------------------------------------------------------------------------
	# ---- return a specific option
	def [](oname)
		x=@o[oname]
		if x == nil
			$stderr.printf "%sinternal error: option %s not found.\n",$err,oname
			exit 1
		else
			return x
		end
	end
			
	# --------------------------------------------------------------------------
	# ---- change a specific option
	def []=(oname,newval)
		x=@o[oname]
		if x == nil
			$stderr.printf "%sinternal error: option %s not found.\n",$err,oname
			exit 1
		else
			@o[oname]=newval
		end
	end
end

# ******************************************************************************
# The main controller class
# ******************************************************************************

class Controller

	# --------------------------------------------------------------------------
	# ---- constructor
	def initialize
		@oc = OptionController.new(ARGV)			
		@StyleLtarr=%w{1 3 7 4 5 2 6 8}
		@StylePtarr=%w{1 1 1 4 4 2 4 4}
		if $GnuPlot4OrNewer
			@StylePrefix="set style line "
		else
			@StylePrefix="set linestyle "
		end
	end	
	
	# --------------------------------------------------------------------------
	# ---- Get the string containing _ALL_ style definitions for gnuplot
	def getStyleString
		style=""	
		(1..@StyleLtarr.length).each do |i|
			style=style+@StylePrefix+(i).to_s+" lt "+@StyleLtarr[i-1]+" lw "+@oc["LineWidth"]
			style=style+" pt "+@StylePtarr[i-1]+" ps 0.5;\n"
		end
		style=style+"set style line 20 lt 7 lw 1 pt 4 ps 0.5;\n"
		return style
	end
	
	# --------------------------------------------------------------------------
	# ---- Starts a command and checks for success
	def printAndRun(com)
		$stderr.puts com
		if not system(com)
			$stderr.printf "Error while starting gnuplot."
			$stderr.printf "Error code: %d\n",$?
			exit 1
		end
	end	

	# --------------------------------------------------------------------------
	# ---- Starts GNUPlot and checks for success
	def plot(comString,doMultiPlot)
		# ---- print the options
		com="echo '\n"+getStyleString+@oc["MiscOptions"]
		com=com+"set multiplot;\n" if doMultiPlot
        com=com+"set terminal dumb;\n" # make plotting work in terminal with sexy ascii art :D
		com=com+"plot "+@oc["Range"]+comString+"\n'| gnuplot -persist"
		printAndRun(com)		
		# ---- convert to PDF
		if @oc["DoPDF"]
			com="ps2epsi foo.ps"
			printAndRun(com)	
			com="epstopdf foo.epsi"
			printAndRun(com)
			if @oc["OutputFileSpecified"]!=""				
				com="mv foo.pdf "+@oc["OutputFileSpecified"]
				printAndRun(com)
			end
			com="rm -f foo.ps foo.epsi"
			printAndRun(com)
		end
	end
	
	# --------------------------------------------------------------------------
	# ---- extract a column with a given index 
	# ---- from a file and write it as single column
	# ---- into another file
	def extractColumn(fromFilename,index,toFile)
		begin
			file = File.open(fromFilename) 
		rescue
			$stderr.printf "%scannot open file '%s' for reading!\n",$err,fromFilename
			exit 1
		end		
		file.each_line { |line| toFile.puts line.split(" ")[index-1] }
		toFile.flush
		file.close
	end
	
	# --------------------------------------------------------------------------
	# ---- run a single plot from a single file
	def runSinFrSin(filename)
		styleArr=@oc["StyleIndices"].split(",")
		com="\""+filename+"\" "
		com=com+"title \""+@oc["TitleString"]+"\" " if @oc["TitleString"]!=""
		com=com+"with "+@oc["LineType"]+" ls "+styleArr[0]
		plot(com,false)
	end	
	
	# --------------------------------------------------------------------------
	# ---- dump the files
	def dumpFiles(openedFiles)				
		i=0
		openedFiles.each do |f|
			begin
				of=File.open("eplot-dump-"+i.to_s+".dat","w")
			rescue					
				$stderr.printf "%scannot open file %s",$err,"eplot-dump-"+i.to_s+".dat"
				exit 1
			end
			f.seek(0,IO::SEEK_SET)
			f.each_line { |l| of.puts(l) }
			f.seek(0,IO::SEEK_SET)
			of.close
			i=i+1
		end
	end
	
	# --------------------------------------------------------------------------
	# ---- Create a titleString which contains the string "empty-notitle"
	# ---- for each file to plot
	def removeDummyTitles(titleCount)
		if @oc["TitleString"]==""
			c=""
			(1..titleCount).each do |i|
				c=c+"@" if i>1
				c=c+"empty-notitle"
			end
			@oc["TitleString"]=c
		end
	end
	
	# --------------------------------------------------------------------------
	# ---- run multiple plots from multiple files
	# ---- argument: list of already opened files
	def runMulFrMulOpenedFiles(openedFiles)				
		titleArr=nil
		titleArr=@oc["TitleString"].split("@") if @oc["TitleString"]!=""
		styleArr=@oc["StyleIndices"].split(",")
		
		# ---- eventually create vertical bars, which are 
		# ---- nothing else than custom made data files
		if @oc["Bars"] != ""
		
			# ---- If no titles are requested, then we create 
			# ---- a dummy title array
			if titleArr==nil
				titleArr=[]
				(1..openedFiles.length).each { |i| titleArr.push("default-title") }
			end
		
			barArr=@oc["Bars"].split("@")
			barArr.each do |b|
				# ---- Parse the bar coordinates
				bd=b.split(",")
				if bd.length!=2
					$stderr.printf "%ssyntax error in option -B or --bar!\n",$err
					exit 1
				end
				
				# ---- Create the file and add it to the list of files
				tmpf=Tempfile.new("eplot")
				tmpf.printf "%s %s",bd[0],bd[1]
				tmpf.flush
				openedFiles.push(tmpf)
				
				# ---- Create the entries in the title array
				len=openedFiles.length
				if titleArr
					if titleArr.length<len
						titleArr.push("bar-notitle") 
					else
						titleArr[len-1]="bar-notitle"
					end
				end
			end
		end
				
		# ---- dump the files if requested
		dumpFiles(openedFiles) if @oc["DumpFiles"]
				
		# ---- process all files
		i=1		
		com=""
		openedFiles.each do |f|
			com=com+", " if i>1
			com=com+"\""+f.path+"\" "
			
			# ---- do we have a title?
			if titleArr
				if i>titleArr.length
					$stderr.printf "%syou need to specify a title for each curve!\n",$err
					exit 1
				end
				case titleArr[i-1]
					when "bar-notitle"
						com=com+"notitle "
						
					when "empty-notitle"
						com=com+"notitle "
						
					when "default-title"
						;
					else
						com=com+"title \""+titleArr[i-1]+"\" " 
				end
			end			
			
			if titleArr!=nil and titleArr[i-1]=="bar-notitle"
				com=com+"with impulses ls "+$barStyleIndex
			else
				com=com+"with "+@oc["LineType"]+" ls "+styleArr[i-1]
			end
			i=i+1
		end	
		plot(com,true)
	end
	
	# --------------------------------------------------------------------------
	# ---- run multiple plots from multiple files
	# ---- argument: list of filenames
	def runMulFrMul(filenames)		
		openedFiles=[]
		filenames.each do |fn|
			if not FileTest.exist?(fn)
				$stderr.printf "%scannot open file '%s' for reading.\n",$err,fn
				exit 1
			end
			t=File.open(fn)
			openedFiles.push(t)
		end			
		runMulFrMulOpenedFiles(openedFiles)
		openedFiles.each { |f| f.close }
	end
	
	# --------------------------------------------------------------------------
	# ---- run multiple plots from a single file
	def runMulFrSin(filename)
		nocols=0
		# ---- Let's see how many columns we have in the file
		File.open(filename) { |x| nocols=x.gets.split(" ").length }
		$stderr.printf "Found %d columns\n",nocols
	
		# ---- Traverse the columns and put them into seperate files
		files=[]
		for i in (1..nocols)
			tmpf=Tempfile.new("eplot")
			files.push(tmpf)
			extractColumn(filename,i,tmpf)						
		end	
				
		# ---- Call it as if we had multiple files
		removeDummyTitles(files.length)
		runMulFrMulOpenedFiles(files) 
		files.each { |f| f.close }
	end
	
	# --------------------------------------------------------------------------
	# ---- run multiple plots from a single file
	# ---- one single column, curves are separated by blank lines
	def runMulFrSeq(filename)			
		files=[]
		begin
			file = File.open(filename)
		rescue
			$stderr.printf "%scannot open file '%s' for reading!\n",$err,filename
			exit 1
		end
		
		startNewFile=true		
		oldFile=tmpf=nil	
		while line=file.gets
		
			# ---- only whitespace in the line?
			if line.split(" ").length<1
				startNewFile=true 
			else						
				if startNewFile
					oldFile.flush if oldFile							
					tmpf=oldFile=Tempfile.new("eplot")
					files.push(tmpf)
					startNewFile=false
				end					
				tmpf.puts line					
			end							
		end
		if tmpf
			tmpf.flush
		else
			$stderr.printf "%sFile '%s' is empty!\n",$err,filename
			exit 1
		end
		file.close
	
		# ---- Call it as if we had multiple files
		removeDummyTitles(files.length)
		runMulFrMulOpenedFiles(files) 
		files.each { |f| f.close }
	end
		
	# --------------------------------------------------------------------------
	# ---- run from a single file. 
	# ---- either a single or multiple diagrams
	def runFrOneOrMoreFiles(filenames)	
		# ---- Multiple curves in a single diagram from a single file
		# ---- or repeated across multiple files
		if @oc["MulFrSin"]				
			filenames.each { |fn| runMulFrSin(fn) } 
			
		else 			
			# ---- Multiple curves in a single diagram from different files	
			if @oc["MulFrMul"]					
				runMulFrMul(filenames)
			
			else
				if @oc["MulFrSeq"]
					filenames.each { |fn| runMulFrSeq(fn) } 
			
				# ---- Default: a separate curve for each file
				else
					filenames.each { |fn| runSinFrSin(fn) }
				end
			end
		end
	end

	# --------------------------------------------------------------------------
	# ---- run on input = standard input
	def runFrStdin
		tmpf=Tempfile.new("eplot")
		$stdin.each_line { |x| tmpf.print x }
		tmpf.flush		
		
		runFrOneOrMoreFiles([tmpf.path])
		tmpf.close
	end	
	
	# --------------------------------------------------------------------------
	# ---- run the application
	def run	
		# ---- run from stdin
		if  @oc["Files"].length < 1
			runFrStdin											
		# ---- run from a given file list
		else 				
			runFrOneOrMoreFiles(@oc["Files"])
		end
	end
end

# --------------------------------------------------------------------------
# The main program
# --------------------------------------------------------------------------

$c=Controller.new
$c.run