using hold on with plotyy

I couldn't find an answer out there, so i'll ask:

I want to plot into one axis many curves (by using a loop), using hold on. How do I use 'hold on' separately for each axis of plotyy?

Then, after this loop, I want to plot a set of points into the second y axis. The set of points does not exist until the loop is done. how do I use plotyy without initially plotting into both axes? can i plot into the second axes afterwards like this?

thanks in advance

Answer 1

[the cyclist]

plotyy() creates two axes on top of each other. The syntax

 >> [ax h1 h2] = plotyy(x1,y1,x2,y2);

will put the handles to both axes in the variable "ax". Then you can use the syntax

 >> hold(ax(1),...)
or
 >> hold(ax(2),...)

to apply the hold to ones set of axes or the other.

[Fangjun Jiang]

+1, nice cyclist! Thank you!

Answer 2

[Rory]

I also found the clear axes command 'cla' to be useful for this: I set up plotyy with two arbitrary X's an Y's, then go in and clear each axis:

[ax h1 h2]=plotyy([0,1],[0,1],[0,1],[0,1]); axes(ax(1)) cla axes(ax(2)) cla

axes(ax(1)); %make axis 1 the current axis hold(ax(1); now populate the first axis

axes(ax(2)); %make axis 2 the current axis hold(ax(2)); and finally populate the second axis.