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I have a (3,4) subplot each showing scatterplots. The ranges of the scatterplots vary so some of my plots have axes x(0-30) and y(0-8), but some have x(18-22) and y(4-7). I have set my xlim to [0 30], and ylim to [0 8] but that sets my axes to never go lower than 0, higher than 30 etc.

How do I set my axis to "stick" at (0,0) for the origin of each plot, and "stick" at 8 for Y and 30 for X.

TIA for any help

update per comment on answer:
Still having the same issue with below code

%% plot

for i = 1:num_bins;

h = zeros(ceil(num_bins),1);

h(i)=subplot(4,3,i);

plotmatrix(current_rpm,current_torque)

end

linkaxes(h,'xy');

axis([0 30 0 8]);
NotMe
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mallow
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1 Answers1

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To programmatically set axis boundaries there are a few useful commands:

axis([0 30 0 8]);  %Sets all four axis bounds

or

xlim([0 30]);  %Sets x axis limits
ylim([0 8]);   %Sets y axis limits

To only set one of the two x limits I usually use code like this:

xlim([0 max(xlim)]);  %Leaves upper x limit unchanged, sets lower x limit to 0

This takes advantage of xlims zero input argument calling convention, which returns an array of the current x limits. The same works with ylim.

Note that all of these commands apply to the current axis, so if you are creating subplots you will need to perform the scaling call once per axis as you build up your figure.

Another useful fatures is the linkaxes command. This dynamically links the axis limits of two plots, including for programmatic resize commands like xlim and UI operations like pan and zoom. For example:

a(1) = subplot(211),plot(rand(10,1), rand(10,1)); %Store axis handles in "a" vector
a(2) = subplot(212),plot(rand(10,1), rand(10,1)): %

linkaxes(a, 'xy');

axis([0 30 0 8]);  %Note that all axes are now adjusted together
%Also try some manual zoom, pan operations using the UI buttons.

Looking at your code, post edit, your use of the plotmatrix function is complicating things. plotmatrix appears to create its own axes to work in, so you need to capture those handles and adjust them. (Also, in the future take h = zeros(..) out of the loop).

To get the handles to the plotmatrix created axes, use the second return argument, like this: [~, hAxes]=plotmatrix(current_rpm,current_torque);. Then collect those for future use.

Finally, the axis, xlim, ylim commands all act on the current axis, (see gca). However the plotmatrix axes are never current, so the axis command has not been affecting them. You can specify the axis to act on, like this: axis(hAxis, [0 30 0 8]);.

Putting this all together (an adding some variable definitions to get your code to execute), and this is what it looks like:

%Define some dummy variables
current_rpm = rand(20,1)*30;
current_torque = rand(20,1)*8;
num_bins = 12;

%Loop to plot, collecting generated axis handles into "hAllAxes"
hAllAxes = [];
for i = 1:num_bins;
    subplot(4,3,i);
    [~, hCurrentAxes]=plotmatrix(current_rpm,current_torque);
    hAllAxes = [hAllAxes hCurrentAxes];  %#ok
end
linkaxes(hAllAxes,'xy');    
axis(hAllAxes,[0 30 0 8]);
Pursuit
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  • Thanks for the reply.I have tried that already but that just sets the minimum x value to 0 but I still get plots where the x axis is in the range of 18-22. I need all of my subplots to be on exactly the same scale.Any ideas? – mallow Mar 21 '13 at 15:45
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    Make sure you set the axis after you plot your data. – Molly Mar 21 '13 at 16:02
  • Added some updates. I suspect `linkaxes` is really what you want. – Pursuit Mar 21 '13 at 16:08
  • to add the confusion the subplots are being called in a for loop, so linkaxes wont work here: for i = 1:num_bins; h = zeros(ceil(num_bins),1); h(i)=subplot(4,3,i); plotmatrix(current_rpm,current_torque) xlim([0 max(xlim)]); ylim([0 max(ylim)]); end – mallow Mar 21 '13 at 16:17
  • Why can't you put `linkaxes(h,'xy');` immediately after the loop? – Pursuit Mar 21 '13 at 16:45
  • STill will not work. Getting different scales. See above code – mallow Mar 21 '13 at 17:32