Selecting data from a plot in a GUI

I have a plot on my GUI and I want to select some points on this plot and save their coordinates to a variable. The variable would have rows containing each point and 2 columns for the x,y values for those points.

I have tried using the brush function to select the data and then save it to a variable, but that is giving me problems.

Any other ideas?

Thanks!

Answer 1

[Fangjun Jiang]

plot(magic(5));
[x,y]=ginput

You can select multiple data points, Press return when you are done.

[Michael]

What if I want to select multiple points at once. I have hundereds of points and I want to select a group of them with a selection box. Is there a similar function for that?

[Fangjun Jiang]

I am not aware of any function for that. You could develop some code to do that since you have the original data for the curve. For example, use [x,y]=ginput(2) to get two data points, then you can select all the data points that is fallen between x(1)<x<x(2) and y(1)<y<y(2).

[Michael]

That worked great. Thanks so much!

Answer 2

[Fangjun Jiang]

Michael, I've been thinking about this problem. You can use Brush on your plot. Click the "Brush" icon, select a group of data points, then select the highlighted data point and right click, you can select "Create Variable" which then will ask you for a variable name. Or, you can select "Copy Data to Clipboard", then in the Command window, you can type MyData=clipboard('paste'). Does this satisfy your need, or you need more formal API to use the Brush functionality? There is a lead in this post but I have not found an API for Brush yet.

Answer 3

[Andy]

An excellent option is provided below:

hBrushLine = findall(gca,'tag','Brushing');
brushedData = get(hBrushLine, {'Xdata','Ydata'});
brushedIdx = ~isnan(brushedData{1});
brushedXData = brushedData{1}(brushedIdx);
brushedYData = brushedData{2}(brushedIdx);
% and similarly for ZData in 3D plots

http://undocumentedmatlab.com/blog/accessing-plot-brushed-data