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Plot a set of data with two different axes.

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PLOT2AXES(X, Y, 'Param1', 'Value1', ...) plots X versus Y with secondary axes. The following parameters are accepted [default values]:
  xloc ['top']: location of secondary X-axis
  yloc ['right']: location of secondary Y-axis
  xscale [1]: scaling factor for secondary X-axis (scalar)
  yscale [1]: scaling factor for secondary Y-axis (scalar)

xscale and yscale can also be an anonymous function that describes the relationship between the 2 axes, such as the equation relating Celsius and Fahrenheit: @(x) 5/9*(x-32)

  xlim [NaN NaN]
  ylim [NaN NaN]:
xlim/ylim in the primary axes (secondary is adjusted accordingly). The default is naturally selected by the plotting function.

PLOT2AXES(@FUN, ...) uses the plotting function @FUN instead of PLOT to produce the plot. @FUN should be a function handle to a plotting function, e.g. @plot, @semilogx, @semilogy, @loglog ,@stem, etc. that accepts the syntax H = FUN(...). Optional arguments accepted by these plotting functions are also allowed (e.g. PLOT2AXES(X, Y, 'r*', ...))

[AX, H] = PLOT2AXES(...) returns the handles of the primary and secondary axes (in that order) in AX, and the handles of the graphic objects in H.

Right-click on the axes to bring up a context menu for adding grids to the axes.

The actual data is plotted in the primary axes. The primary axes lie on top of the secondary axes. After the execution of this function, the primary axes become the current axes. If the next plot replaces the axes, the secondary axes are automatically deleted.

When you zoom and pan, the secondary axes will automatically adjust itself (only available on R2006b or later). For older releases of MATLAB®, there will be a "Fix Axes" menu, which let's you adjust the limits.

PLOT2AXES('FixAxes') fixes the secondary limits of all figures created using plot2axes.

Example 1:
  x = 0:.1:1;
  y = x.^2 + 0.1*randn(size(x));
  [ax, h] = plot2axes(x, y, 'ro', 'yscale', 25.4);
  title('Length vs Time');
  ylabel(ax(1), 'inch');
  ylabel(ax(2), 'millimeter');
  xlabel('time (sec)');

Example 2:
  x = 1:10;
  y = 50*rand(size(x));
  [ax, h] = plot2axes(x, y, 'ro', 'yscale', @(x) 5/9*(x-32), ...
      'xscale', 2.20);
  xlabel(ax(1), 'kg'); ylabel(ax(1), 'Fahrenheit');
  xlabel(ax(2), 'lb'); ylabel(ax(2), 'Celcius');

Comments and Ratings (8)


Emilie (view profile)

This is great, just what I was looking for! But (a stupid) question - how do I modify the line style and color properties of the line I've now plotted?

Yuri K

Yuri K (view profile)

When you add large enough title to the primary axes (which is current), it get shifted down, but not the secondary axes. If title applied to the secondary axes, no shift, but the title may appear too high. Took me some time to figure out the problem. Anyway, great function. Thanks

Jiro Doke

Kevin: I have uploaded an updated version that should let you plot on a uipanel.

Sloane: Yes, that is a limitation. I have indicated in the help text that the axes relation must be linear.

Kevin Turner

For the most part, this is a great tool. However, in cases where the parent of the current axes is not a figure (i.e. in a GUI application the parent may be a uipanel), then the function will not work as is.

Sloane Wiktorowicz

Runs into trouble when having inversely proportional axes (e.g., wavelength on bottom and energy on top), because one axis must be reversed. This can be overcome by editing the function plotxx.

Frode Seland

Garner Izru


adi sayoga



Updated license


Added auto adjust of axes limits (works R2006b and later). Now works with nonlinear scaling. Added ability to add grids interactively. Use of function handles instead of strings.

Added option for specifying an equation for XScale and YScale

v1.2 - remove tick labels for secondary axes if no scaling factors are specified. Also, fixed bug in matching the scaling type (linear or log).
v1.3 - added the 'Fix Axes' menu for adjusting the secondary axes limits after zooming.

MATLAB Release
MATLAB 7.9 (R2009b)

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