Extract X,Y data from scatter plot

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Hi All,
Could you giving a code or advice how to extract X,Y data from a scattered plot?
I have tried several ways following previous suggestions on website, none of that works for me.
I've attached the figure as what I want to extract those values out.
I strongly hope that one of you might help me solve this issue.
Thanks in advance,
Pete
  4 Comments
Cris LaPierre
Cris LaPierre on 26 Sep 2020
If you haved the data used to create the plot, there are better ways of doing this. You can figure out what X is from the plotting code. What is you plot command?
Pichawut Manopkawee
Pichawut Manopkawee on 26 Sep 2020
This is a plot command
semilogx(saproduct,laplacian,'k.','markersize',8);
saproduct and laplacian are two matrix containing values of 756x519 single

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Accepted Answer

Cris LaPierre
Cris LaPierre on 26 Sep 2020
Assuming you have a *.fig file and not a .png, first open the fig file in MATLAB then run the following code.
s=findobj(gca,'Type','Scatter');
X = s.XData;
Y = s.YData;
  6 Comments
Cris LaPierre
Cris LaPierre on 26 Sep 2020
Edited: Cris LaPierre on 26 Sep 2020
Now we're getting somewhere! When passed matrices, MATLAB will plot each column as its own series. That means your semilogx plot is made up of 519 data series with 756 data pairs in each one. Since you are setting your marker color, you probably noticed that (each series is assigned a different color). To extract the data from the figure, you would have to loop through each line object, combining the data as you go.
Luckily, since you have the data and are creating the plot, we don't have to do that. We can use linear indexing instead to create the exact same semilogx plot, but with all the data in a single series. This makes it easier to figure out the [X,Y] pairing. Linear indexing turns both matrices into column vectors by stacking the columns on top of each other (column 2 is directly under column 1, etc).
X = saproduct(:);
Y = laplacian(:);
semilogx(X,Y,'k.','markersize',8)
X and Y are vectors with size 392364 x 1.

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