Generating a plot from selected figure point

Hello,

I'm a relatively new matlab user and not too used to mouse click-related functions. What I have is a scatterplot of 2 parameters obtained by computations done on a series of waveforms.

What I want is, whenever I click a point on the plot, for a plot of the waveform corresponding to this point to appear in the secondary boxed figure. In order to do that, I'd like to get the position of either the x or y values (since it would be the same for both) of the point within the array that was used to create the scatterplot.

Following that, I can easily find the corresponding waveform. Getting there however, is the point I struggle with:

- I'm not sure how to code the selection by mouseclick. I find the documentation a bit obscure for a first-time use.

- I want the waveform plot to update every time a new point is selected, replacing the previous one. I don't need to do anything in particular for that, do I?

- I can't simply take the coordinates of the points since several points overlap and it doesn't tell me which waveform it came from.

Also, if you think you have a better idea of how to go about this, do tell!

Answer 1

[Ameer Hamza]

You can use the ButtonDownFcn callback: https://www.mathworks.com/help/matlab/ref/matlab.graphics.axis.axes-properties.html#budumk7_sep_shared-ButtonDownFcn and CurrentPoint property: https://www.mathworks.com/help/matlab/ref/matlab.graphics.axis.axes-properties.html#budumk7-CurrentPoint of axes object to find out which point was clicked by the user. For example, try this

ax = axes();
ax.ButtonDownFcn = @cb;

cb is defined in cb.m file as

function cb(ax,~)
    disp(ax.CurrentPoint);
end

Although it does not give the index in your data points, you can find the closed point in your dataset to the CurrentPoint (e.g., use Euclidean distance) and then plot on small axes accordingly.

[Charles-Elliott BARTON]

Thanks for the answer!

Didn't help in the end, but that's because my problem is with the overlap of points, which I can't do anything about.

But on the subject matter; this kind of function gives me the coordinates of the region I click on in the plot; what I'd like to do is to get the coordinates of the points that are plotted. A bit like the default function which displays those coordinates on the graph except I'd want them returned in an array.

[Ameer Hamza]

Yes, I mentioned in the answer that it would not give the coordinates of your data points. But you can find the closest point. For example, I have datapoints

x = [0.5 0.5;
    0.5 0.6;
    0.6 0.6]

So if the callback return

y = [0.55 0.45]

then i can use pdist2 to find the corresponding point in x

[~, index] = min(pdist2(x,y))

[Charles-Elliott BARTON]

Oh, I see. Alright, thanks!