Yes you can. For example suppose you have a plot of a Bessel function :

myBesselPlot = Plot[BesselJ[1, x], {x, 0, 6 \[Pi]}, PlotStyle -> Blue]

Now to extract the data from this plot, you can can use the Cases function. This function allows you to search a Mathematica expression using a specified pattern. In the case of the above plot all the data for the actual plot is contained in a graphic primitive called Line, which has the structure:

Line[{{x1,y}},{x2,y2},...{xn,yn}}}

where {xi,yi} are the data points. You can extract this date using the Cases function with the following pattern: Line[{x__}]->x.

What this pattern does is extract the Line primitive and then replace the argument of the Line primitive which is the actual coordinate data, with the data itself. Recall the BlankSequence (double underscore) in the pattern matches with one or more Mathematica expressions. In our case this would be the list of data pairs. Thus in the case of the above plot we would evaluate:

mydatapoints=Cases[myBesselPlot, Line[{x__}] -> x, \[Infinity]]

By specifying Infinity, Cases will search at all levels of the expression for a match.

mydatapoints is now a list of all the data points used to construct the Bessel plot.

The bottom line given any mathematica plot you can extract the data used to create that plot. I have attached a PDF of a Mathematica notebook that shows the capability of this approach. Note, with some modification, these ideas can be extended to extract data from other Mathematica plot function, such as ContourPlot, Plot3D etc.

I am using the following code to save my generated image file to my computer. I hope it works.

plotname=ListPlot[{mylist},

Frame -> True,Joined->True,

PlotMarkers -> {{\[EmptyCircle],9}},

Background -> White, Axes->False,

BaseStyle -> {FontFamily -> "Arial", 10}

]

Export["/home/user/img.eps", plotname, "EPS" ,ImageSize -> 250,ImageResolution->1000,"CompressionLevel" -> 0]

Respected Prof.Higgins Thank you very much for your answer and the attachment. It is really helpful for me to know new thing from Mathematica. Thank you very much.

Sakthi, Since you are interested in extracting the data from a Mathematica ContourPlot, I have attached a PDF of a Mathematica notebook that outlines how one goes about doing this. It requires knowledge of what is known as a GraphicComplex, and how to extract data from a GraphicComplex.

try this

http://mathematica.stackexchange.com/questions/19859/plot-extract-data-to-a-file

and use PlotRange-> All in order to get all data points within the limits you want.