Multiple plots using a method on single axis?

I have a method that plots an array of data onto an axes in my GUI. I want to be able to call this method in a for loop and all the data that is plotted be on the same axes and not reset every time the method is called. Is this possible?

Answer 1

[dpb]

Sure, just set hold on for the figure after the first plot...

NB: To cycle colors/linestyles you'll have to increment and pass a color/linestyle argument for each; otherwise Matlab starts counting over from the beginning of the default order. I think this is a glaring weakness in the controllability as it's such a common desire to add incrementally as opposed to always having all the data that can make a single call in which case the colors/linestyles do cycle automagically. But, several requests for it as an enhancement over the years went unheeded so I've given up... :(

[Cameron Jewell]

The plot command is called over 1000 times. Do I add the hold on command after the first plot in the loop thus using hold on after every successive plot?

[dpb]

No need; only after the first until you wish to reset and start over, then set hold off. See

doc hold  % for details
doc axes  % for more discussion of 'nextplot' property

There are examples of also updating graphics with lower-level modifications of simply adding to the data arrays instead of using plot in the graphics section as well which may be more apropos if you're calling it this many times.

[Walter Roberson]

You only need "hold on" once, but it does not hurt to call it extra times.

Duane: Starting from R2014b, "hold on" does cycle colors between successive plot calls. See http://www.mathworks.com/help/matlab/graphics_transition/why-are-plot-lines-different-colors.html

[dpb]

While the extra hold on operation "doesn't hurt" there's just something about extra operations that aren't needed that seems reasonable to avoid. I've often wondered (but never actually tried to measure) whether it's more expensive to have hold on every pass inside a loop such as OP's or to do the test on a counter or a flag and branch. If it's at all convenient I'm anal enough that I'll rearrange the loop and move the initial case and the hold command to precede the loop to avoid both. It's just ugly, no matter what way you go at it.

And on the color cycling, just think--only 25+ yr since my first enhancement request for it!!! :)

I've not yet tried one of the later releases given all the comments on how much more memory and processor power is required over 2K 12b. Is it still so, I can only put 4GB in this machine which had to do to be able to use this version.

Answer 2

[Walter Roberson]

Use

hold on

if you want to have all of the objects appear together on the same axes.