Aligning ytick marks in a yyplot

I am currently trying to make a plot with two y axes using plotyy. However, I needed to change the y limits on both axes. After I changed the y limits the y ticks on the right and left no longer line up, which makes the plot look poor when I turn the grid on. I am wondering if there is a way to line up the YTick marks. I would like for them to be aligned the way they are when you first make the plot with plotyy. Thanks

Here is my sample code:

t = 1:100;
y = exp(-(1/100)*(t-50).^2);
rr = -0.1 + 0.2*rand(100,1);
y = y+rr';
c = cumtrapz(y);
[ax] = plotyy(t,y,t,c);

set(ax(1),'YLim',[0 inf])

set(ax(2),'YLim',[0 inf])

set(ax(1),'YTick',0:.1:1)

set(ax(2),'YTick',0:2:20)

grid on

Answer 1

[Walter Roberson]

No. Setting the YLim upper limit to infinity has no documented meaning, and in practice has subtle interactions with "axis tight" (or not) that make it difficult to say what the "right" solution is.

The calculations that you would need to do in order to align the ticks depend upon having finite ylim for both axes.

[Gustavo Goncalves]

Ok suppose we make the ylimits finite, then what.

t = 1:100;
y = exp(-(1/100)*(t-50).^2);
rr = -0.1 + 0.2*rand(100,1);
y = y+rr';
c = cumtrapz(y);

[ax] = plotyy(t,y,t,c);

set(ax(1),'YLim',[0, 1.1*max(y)])

set(ax(2),'YLim',[0, 1.1*max(c)])

set(ax(1),'YTick',0:0.1:1)

set(ax(2),'YTick',0:2:20)

grid on

[Walter Roberson]

In that case,

yt1 = get(ax(1), 'YTick');
yL1 = get(ax(1), 'YLim');
t1ratio = (yt1 - yL1(1))./(yL1(2)-yL1(1));
yL2 = get(ax(2), 'YLim');
yt2 = t1ratio .* (yL2(2)-yL2(1)) + yL2(1);
set(ax(2), 'YTick', yt2)

This relies on the YLim being finite (as otherwise the range is infinite and you end up with 0 for the proportional ratios.)

[Gustavo Goncalves]

Thanks, this solves my problem. I greatly appreciate it.