Kushal , kD & FOSS

You can do this with R.

See: http://www.harding.edu/fmccown/R/

That looks simple enough for gnuplot. I find this site pretty useful (and has a two-axis example):
http://t16web.lanl.gov/Kawano/gnuplot/plot1-e.html#5.2

It looks like it was done using GLE.

http://glx.sourceforge.net/examples/2dplots/index.html

http://zoonek2.free.fr/UNIX/48_R/04.html

try the R progmanning language. it has many plot features. if you are comfortable with matlab R shouldn’t be a big stretch

matplotlib can do that easily.

There is an example of a shared x-axis plots in the two_scales.py example file provided in matplotlib docs in Fedora.

-jef

This example is something similar to what you wish to do.

http://matplotlib.sourceforge.net/examples/axes_grid/demo_parasite_axes2.html

matplotlib has a nice gallery at: http://matplotlib.sourceforge.net/gallery.html
Just click an image to get the code.

This code should pretty much solve your problem:
import numpy as np
import matplotlib.pyplot as pl

x, y1, y2 = np.loadtxt(‘test.dat’, unpack=True)
pl.plot(x, y1, ‘-o’, label=’A 280 nm’)
pl.plot(x, y2, ‘-s’, label=’Enzyme activity’)
pl.legend(loc=’upper center’)
pl.ylabel(‘$A_{280}$ [nm]‘)
pl.text(8, 1, ’1′)
pl.text(10, 0.9, ’2′)
pl.text(40, 0.8, ’3′)
pl.show()

Thank you all for the reply :)
Now I am going to try the methods told by you.

GNuPlot can do that with less than 10 lines of code :)
http://t16web.lanl.gov/Kawano/gnuplot/gallery/index-e.html

Ping me if you need help.

Try xmgrace.

You can use “qtiplot” and use “double y” plot option.

+1 for R: it reads you text file and you can do alto multiple plots with lattice

http://www.r-project.org

Since everybody pointed at some code, time to show gnuplot power

Reference: http://t16web.lanl.gov/Kawano/gnuplot/plot1-e.html#5.2

The below 4 lines will get you the two axes. Cosmetic changes can be done to make the graph look best.

gnuplot> set xrange [0:2*pi]
gnuplot> set yrange [-1:1]
gnuplot> set y2range [0:1]
gnuplot> plot sin(x) axis x1y1, \
sin(x)**2 axis x1y2

that’s a GLE graph.

I would recommend RRDTool http://oss.oetiker.ch/rrdtool/.
It has bindings for a lot of languages.

good luck