Find the coordinates of a point chosen on a plot

Hello,

So I've been using ginput to select points on a plot

My plot consists of time(x) and velocity(y).

Below is my user-selected points.

[Userx,Usery] = ginput(1); 

However, I noticed it doesn't actually select points from the voltage vs. time graph and instead just a point in the figure screen.

How can I get the nearest data point of the actual plot?

I've found one solution is to use this user created script file:

https://www.mathworks.com/matlabcentral/fileexchange/3265-magnetginput

[Dinuka Madhumal]

Can anyone help me, what is the problem of this error - Undefined function or variable 'pdist2'. . Do i want to make the 'pdis2' function ?

Answer 1

[darova]

Short example

x = linspace(0,2,20)';             % generate some data
y = sin(x);
plot(x,y,'.-b')
xy = ginput(1);                    % get point
[~,ix] = min(pdist2([x y],xy));    % find closest point
hold on
plot(x(ix),y(ix),'or')             % display closest point
hold off

[Nom]

Awesome I pretty much used a very simple formula which does the same thing you have listed above.

        [x, ~] = ginput(1); %xmouse, ymouse
        [~, xidx] = min(abs(time-x)); %closest index
        xx = time(xidx); %extract

[Dinuka Madhumal]

Can anyone help me, what is the problem of this error - Undefined function or variable 'pdist2'. . Do i want to make the 'pdis2' function ?

[Fangjun Jiang]

pdist2() comes from Statistics and Machine Learning Toolbox.

Answer 2

[Fangjun Jiang]

Use data cursor, set "SnapToDataVertex" to be "on" and then get the position. See example in

doc datacursormode

[Nom]

Is there a way to do this using ginput, at least where I can see the x-line and y-line of the crosshair which chooses the point?