Creation of line between axis and point in scatterplot?

The question pretty much says it all. How do you visualise a line between any point (even a moving point), directly towards the x-axis?

Answer 1

[dpb]

doc line % maybe???

There's a topic on animation techniques in the section on enhancing graphics that may be useful as well...

But in general,

hold on
line([x x]', [y 0]')

will add the line. For more generality, use

yl=ylim;  yl=ylim(1);

for the 0 to get the value of the y axis lower limit

Image Analyst noted that--

If it's a moving point, you'll have to get the handle to the line so you can delete it when you draw the next one.

hLine = line(......
% move coordinates, then
% delete last line
delete(hLine);
% Draw new line
hLine = line(................

To which dpb agreed but noted that there's an easier way:

Do need the handle, yes...but only need to update the data point(s) that are moving/moved from one to another in the [x|y]data properties, not actually delete old/draw new but just change the data in the one...that automagically erases the other.

hL=line([x x]', [y 0]');
...something that changes x and y...
set(hL,'xdata', [x x], 'ydata', [y 0]);

[Jeppe Sørensen]

Thank you very much. That was exactly what I needed!

[Image Analyst]

Then please mark it as "Accepted" so dpb can get credit for it.