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Old 03-14-2007, 09:54 PM   #1
Registered: Jan 2005
Location: Pittsburgh
Distribution: Ubuntu
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gnuplot, pull X data from file, specify Y data at cmd line?

Hey all,

I was wondering if its possible with gnuplot, for me to pull the X axis points from a file while plotting, but on the gnuplot command line specify Y for all points. Something like this:

plot "data/flood" Y 3 with linespoints title "degree_in"
that would get all of the X-axis data points from data/flood and use Y=3 for all of the points. Is this possible some how? You might say to simply add 3 to the file for all of the points, but I have different plots which will be using this same file for which I want the Y to be different. So I was hoping to be able to specify it on the cmd line
Old 03-14-2007, 11:34 PM   #2
Registered: Feb 2007
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I have seen no indications that this is possible, and so when I want to do something similar to this, I use python and have it do whatever processing I want, and then use gnuplot just for plotting.
Old 03-15-2007, 02:33 AM   #3
Registered: Mar 2005
Distribution: FC5 on disk, Knoppix as LiveCD
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I have had a similar/almost same problem many times. But in the end, i ended creating a file or a stream by sed, awk or any other program and then piping it to gnuplot, e.g. this one is from 2 days ago:

cat ../../input/ | sed -e "s*OUTPUT*atts_$FUN.eps*g" < \

Here i was only changing the EPS output file name, but I am sure that you can understand my approach. Btw. if you perhaps need to concatenate columns within input file, use "paste" unix command.
Old 03-15-2007, 06:27 AM   #4
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Registered: Sep 2005
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Originally Posted by /tmp/data
20 bla
30:oh my god
./scrunch /tmp/data

scrunch script:
[[ "$1x" == "x" ]] && exit
cat > $tmp << EOF
set terminal postscript eps colour
set output "scrunch.eps"
set yrange [0:5]
set xlabel "Data"
set ylabel "Flood"
plot \
"<awk -F'=| |:' '{print \$1\" \"3}' $1"  using 1:2 title "degree_in" with lines
gnuplot < $tmp
rm $tmp
Now you should have scrunch.eps in current directory

Last edited by nx5000; 03-15-2007 at 06:29 AM.
Old 03-15-2007, 09:56 AM   #5
Registered: Mar 2006
Location: Ekaterinburg, Russia
Distribution: Debian, Ubuntu
Posts: 687

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If I understand your problem right, following approach may be useful:
gnuplot> plot "<(awk '{print $4,$3}' u-log-10)" w l
Here I'm filter out 4th and 3rd columns from file u-log-10 (awk '{print $4, $3}' u-log-10), and then plot this data with style `lines'. As I understand, gnuplot syntax
plot "< source-of-data"
allows to plot the data from standard output of any program (e.g. `plot "<seq 10" ' will plot the straight line).

So you can plot all points from "data/flood" being projected to the line y=3 as follows:
plot "< awk '{print $1, 3}' data/flood" with linespoints title "degree_in"
P.S.: I suggest you to take a look at plotutils package. Using `graph' util from there may be much more handy in noninteractive mode.
Old 03-16-2007, 12:32 AM   #6
Registered: Feb 2005
Location: Bogotá, Colombia
Distribution: Slackware
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alternatives to gnuplot

have you tried PyX, or PyXPlot?


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