How to plot left and right y-axis that belong to the same data points

Dear All,

I am trying to create a plot that displays 2 y-axis (one on the left and one on the right). I have tried using the plotyy function, however the results are not the ones I am looking for.

I am uploading a picture that shows what I want to get:

The left y-axis is a difference in degrees while the right y-axis is an error in % for each point in the plot. For example, the point corresponding to the value of 40 on x-axis, has -0.01 degrees difference and an equivalent of 0.0349% error.

I hope I have expressed the issue clearly and I hope there is a solution :)

Thank you all,

Radu

Answer 1

[pfb]

So if I get it right, you want to represent the same data using different units. I can see why plotyy is not the right tool.

You could use a second transparent set of axes.

If h is the handle to your axes, (the one for the left scale),

 p = get(h,'position'); % gets the axes position
 a = axis(h); % gets the axis limits 
 h2 = axes('position',p,'color','none'); % draws another axes with transparent background over h.
 axis(a); % sets the same limits as in h
 hold on;

then you need to get rid of the duplicate stuff. It's probably best to keep only the righ y axis

 box off
 set(h2,'Xtick',[],'YAxisLocation','right');

Next you need to set the same ticks on the left and right axis

 set(h2,'Ytick',get(h,'Ytick'));

Finally, you take care of the new unit

 set(h2,'YtickLabel',ytl);

where ytl is a vector containing the appropriate values in the other unit of measure. This should work

 set(h2,'YtickLabel',abs(get(h,'YTickLabel'))/0.01*0.0349);