Together with the pratice to save handles from plots and include them in the legend-command, “hold all” is one of the very first things I teach MATLAB newbies (if I get the chance).

Saving the hold state and reinstating is polite in utility plotting functions. I second the thought that being able to do something like the following would be nice built in behavior:

% Save state
old_hold = hold;
…
% do stuff including hold on/off/all commands
…
% Reinstate state
hold(old_hold);

One approach that I’ve been trying recently is building my arguments in a cell array as I’m assembling what I what plotted rather than call subsequent plot/line, etc. I doesn’t make any sense really for a single plot, but I found myself reusing the plot variables many times, like when I have a series of baselines to compare against, and putting them in a cell array made for a nice compact way to plot the same quantities again.

curvs_baseline=[{x1} {y1} {'r-'}];
...
cv=[curvs_baseline {xn} {yn} {'g-'}];
hc=plot(cv{:})

All in all, I’ve been finding lots of new uses for cell arrays, that I’m still discovering after 10+ years programming in MATLAB.

My bad. I forgot to insert hold off between my plots so old lines were being held onto and plotted on top of new ones. legend seems fine. I updated the post to insert the commands and recreate the graphs.

–Loren

Anyway, nice to know I had not noticed this hold all.
I don’t use hold much, or plot. I usually end up tweaking each line saparately anyway, so I use line in the first place.

If you get the handles to the plots, e.g.,

hold on
h1 = plot(....)
h2 = plot(...,'r')

then you can just use delete to get rid of the lines you don’t want, e.g.,

delete(h2)

With different scale data, you might want to try plotyy as well.

–Loren

first of all thanks for the blog, I appreciate your ideas and tips.

When I read this one I thought I could ask a question that is related but is not quite congruent.

The situation I fac quite frequently is that I plot two sets of data to compare like this:

plot(time1,data1)
hold on
plot(time2,data2,'r')

I am not all that itchy about the exact colors and things. However, what frequently happens is that data1 and data2 are scaled differently so data2 reners data1 as a flat line in the plot, another thing is that time1 and time2 might be different units (time1 in sceonds time2 in ms).

The only solutions I know of so far are a) be really careful before you plot (well …) b) start over again with clf.

What I am looking for would be some “undo” command that removes the effect of the last plot command so I could do

plot(time1,data1)
hold on
plot(time2,data2,'r')

UNDO THE LAST PLOT

data2 = scale_function(data2);
plot(time2,data2,'r')

This would be especially convenient in situations where data1 gets erased from memory or is in different levels of memory.

Cheers
Harald

-Thierry