Too many points on x-axis

If you run the following script, Matlab uses 0.5 increments on the x-axis. This gives the wrong label, since it starts over again after 6 points on the x-axis. Does anybody know how to make sure that the increments are made so that the labels get correct?

test= rand(11,8,6);
test2=test

Alder = {'<20', '2029','3039','4049','5059','6069','>70', 'all'};
Aar = {'2011', '2012', '2013_1', '2014_1', '2014_s2', '2014_s5'};

nAlder = length(Alder);
nAar = length(Aar);

figure
hold on
for iAlder = 1:nAlder
  plot(squeeze(test2(11,iAlder,:)));
set(gca, 'XTickLabel',Aar)
end
hold off

Answer 1

[Karl]

Putting the following line between the plot-command line and the XTickLabel-command worked

set(gca, 'XTick',[1 2 3 4 5 6])

Does anybody know why Matlab uses 0.5 increments on the axis? Is this always a problem, so that one always has to use the extra command line listed above in cases like mine?

[Iain]

Matlab just runs through a set process for determining the tick values. If you have more than 6 x values, you'll see the tick locations change.

If you want specific tick locations, you need to specify them.

[Karl]

The funny thing is that there are only 6 values originally...

Answer 2

[Jan]

Perhaps this helps:

figure
data = squeeze(test2(11, :, :));
plot(1:length(Alder), data);  % perhaps: data.'
set(gca, 'XTickLabel', Aar, 'XTick', 1:length(Alder))

[Karl]

The same problem appears when running your commands.

I think this illustrates the source of the problem:

test= rand(11,8,6);
figure
hold on
for i= 1:8
  plot(squeeze(test(11,i,:)));
end
hold off

Try running the commands above. You will see that there are 11 x-axis "labels/points" with 0.5 increments, dispite that there are only y-vaules for 6 of these points. I think this is the source of the problem. When one uses XThickLabel and a 1x6 vector, it will be repeated after the 6th point/label in the original plot. The question is why Matlab does not make 6 points in the first place. Has it something to do with the test-matrix having 11 rows?

[Iain]

No. It simply comes up with what matlab reckons the best scaling is for the plot. It seems to try to ensure that there are BETWEEN 7 and 11 ticks.

Try:

 for i = 1:30
  figure
  plot(randn(i,1))
 end

You'll see what I mean.