Create Chart with Two y-Axes

Plot Data Against Left y-Axis

Create axes with a y-axis on the left and right sides. The yyaxis left command creates the axes and activates the left side. Subsequent graphics functions, such as plot, target the active side. Plot data against the left y-axis.

x = linspace(0,25);
y = sin (x / 2);
yyaxis left
plot(x,y);

Plot Data Against Right y-Axis

Activate the right side using yyaxis right. Then plot a set of data against the right y-axis.

r = x.^2/2;
yyaxis right
plot(x,r);

Add Title and Axis Labels

Control which side of the axes is active using the yyaxis left and yyaxis right commands. Then, add a title and axis labels.

yyaxis left
title('Plots with Different y-Scales')
xlabel('Values from 0 to 25')
ylabel('Left Side')

yyaxis right
ylabel('Right Side')

Plot Additional Data Against Each Side

Add two more lines to the left side using the hold on command. Add an errorbar to the right side. The new plots use the same color as the corresponding y-axis and cycle through the line style order. The hold on command affects both the left and right sides.

hold on

yyaxis left
y2 = sin (x / 3);
plot(x,y2);
y3 = sin (x / 4);
plot(x,y3);

yyaxis right
load count.dat;
m = mean(count,2);
e = std(count,1,2);
errorbar (m, e)

hold off

Clear One Side of Axes

Clear the data from the right side of the axes by first making it active, and then using the cla command.

yyaxis right
cla

Clear Axes and Remove Right y-Axis

Clear the entire axes and remove the right y-axis using cla reset.

cla reset

Now when you create a plot, it only has one y-axis. For example, plot three lines against the single y-axis.

xx = linspace(0,25);
yy1 = sin (xx / 4); 
yy2 = sin (xx / 5); 
yy3 = sin (xx / 6);
plot(xx,yy1,xx,yy2,xx,yy3)

Add Second y-Axis to Existing Chart

Add a second y-axis to an existing chart using yyaxis. The existing plots and the left y-axis do not change colors. The right y-axis uses the next color in the axes color order. New plots added to the axes use the same color as the corresponding y-axis.

yyaxis right
rr1 = exp(xx/6);
rr2 = exp(xx/8);
plot(xx,rr1,xx,rr2)