auto format x axis

In an attempt to change the x-axis format on a histogram (placed on a Axes object) from engineering format to just a number I have read that this can be done by using the "XTick" property of the axes.

I have images that have a greyscale upto 20500 and when I let matlab automatically control these it reverts to engineering mode. I only need 5 ticks and so was wondering how to use the following to change the ticks. They are by default set at 0, 0.2,0.4,0.6,1

XTck=get(handles.axes6,'XTick')

What i need is a way to take the current max value (20500) in this case and then work out the nearest multiple of 5 (that is larger than this value), and then modify the ticks by this.

e.g. in the above, if I made the max value 25000, then each one of my ticks will be 5000, so I could presumably change my ticks now by:

set(handles.axes6,'XTick', XTck*500)    ??

Thanks for any comments Jason

Answer 1

[Mischa Kim]

Jason, this should do:

t     = 0:4700;
y     = rand(1,length(t));          % your data

t_lim = 1e3*ceil(t(end)/1e3);       % get axis limit: 5000
t_ax  = 0:t_lim;
n_int = 8;                          % define # of intervals
t_int = t_lim/n_int;

tt    = t_ax(rem(t_ax,t_int)==0);   % find tick locations
ttlab = num2cell(tt);               % and generate tick labels
plot(t,y)
set(gca,'XTick', tt, 'XTickLabel', ttlab)

assuming that your axis limits are 1000s. If you don't even know the order of magnitude of data points a priori (e.g., there are only 5 data points) then you need some more logic (such as a log10() ) to get the scaling factor, which is currently set to 1e3=1000.

[Jason]

Many thanks for your help Mischa. the only problem I have is that my data is variable and so I cannot fix the t=25000. sometimes the max data may be 4700 in which case t=5000. Can finding this "t" value be automated.

[Mischa Kim]

See extended code above.

[Jason]

For anyone else, if you use an axes to display the data on using GUIDE, then change the last line to:

set(handles.axes1,'XTick', tt,'XTickLabel',ttlab);

where in my case, my graph is drawn on axes1.

Answer 2

[Azzi Abdelmalek]

Maybe you need XtickLabel property