shell script of gnuplot: about various input files in a single graph for compare the lines

Question

I am trying to plot a graph and save it as file using gnuplot. I have various text files. The number of text files is not sure. Each text file contains two columns. The text file is about linear absorption spectrum. The first column is the frequency and the second is the intensity. I want to compare the difference between the spectra by plot them in a single graph for all the files. I am using this script to do that.

#!/bin/bash

# plot linear absorption spectrum (las)
# Usage:
# ./lasplot.sh a.ods b.ods c.ods ..

j=1
for i in $*
do
    echo "Normalization $i"
    maxle=`cat $i|tr -s "," " "|awk 'BEGIN{max=0} {if($2>max) max=$2}END{print max}'`
    echo "  The max value is $maxle"
    max[$j]=$maxle
    filename[$j]=$i
    ((j=$j + 1))
done
num=$#
echo ${filename[*]}
echo $num

read -p "Please select set data range (1) or auto set(2): " setrange
case $setrange in
1)
   read -p "set min x range: " minx
   read -p "set max x range: " maxx
   ;;
esac

# call gnuplot to plot the 1D map
gnuplot << EOF
set datafile separator ","
set title 'Linear Absorption Spectra'
set xlabel '{/Symbol w} (cm^{-1})'
set ylabel 'Intensity (a.u.)'

#set data range
if (${setrange}==1){
set xrange [$minx:$maxx]
set yrange [0:1.1]
} else {
#set xrange [0:50]
#set yrange [0:50]
}

set size 1,1
set key right top

plot "${filename[1]}" using 1:(column(2)/${max[1]}) with lines  linewidth 2 ,\
"${filename[2]}" using 1:(column(2)/${max[2]}) with points pointtype 21

pause mouse keypress "Type a letter"

set term pdfcairo font "arial,12"
set term pdfcairo enh
set term pdfcairo size 6,5
set output "las.pdf"
plot "${filename[1]}" using 1:(column(2)/${max[1]}) with lines  linewidth 2 ,\
"${filename[2]}" using 1:(column(2)/${max[2]}) with points pointtype 21

EOF

My script can only plot two text files? How can change it to plot multiple input files?

ewcz ewcz · Accepted Answer · 2016-09-19T09:22:34

you could prepare the plot command in your script before invoking gnuplot, store it into a variable and then reuse it in the gnuplot input (also avoiding thus repetition):

plotCmd="plot"
for((i=1;i<=${num};i++))
do
    if [ $i -eq 1 ]; then
        join=" "
    else
        join=", "
    fi
    plotCmd="${plotCmd}${join}\"${filename[$i]}\" using 1:2 with lines"
done

and then:

gnuplot << EOF

... some other stuff ...
${plotCmd}

EOF

shell script of gnuplot: about various input files in a single graph for compare the lines

1 Answers