以八度为单位获取绘图上数据点的值

Question

I am trying out octave as an alternative to matlab and it looks like the graph plot in octave is not as interactive as matlab

I want to find out the value of the x and y coordinates of a data point on the plot by clicking on it

I have seen the ginput function, but while my figure is open, if I call the function, click on a point in the figure and then press the Enter key, I get the following result:

[x, y, buttons] = ginput ()  
x = [](0x0)
y = [](0x0)
buttons = [](0x0)  

While messing around I did manage to get proper coordinate values once

figure(1); [x, y, buttons] = ginput ()
x =  69.09677419354838
y =  127.2917862029395
buttons = 13  

but I am not sure what I did different, and I haven;t been able to make it happen again

How can I click on a data point in in Octave figure and find it's value (both x and y, or at least just y)? Is it possible to select an exact data point on a plot using the ginput or any other function in Octave?

Answer 1

The behaviour described above seems to be a bug with the QT interface. The fltk interface works as expected. Try:

graphics_toolkit fltk

to enable it.

I will file a bug in the meantime. bug submitted

PS. Keyboard events seem to be detected normally, but mouse events are not, hence the empty lists. The '13' accidental output must have been from pressing 'small enter' and registering a newline keyboard event, before pressing 'big enter' thus forcing ginput to return.

UPDATE it appears that switching back to the qt interface and trying again now allows mouse events to work. This has persisted following an octave restart. Weird bug.