find line handles related to legend entries

Before R15 I used to be able to find the handle of an object, referred to in the legend of an existing graph by a certain legend string, say "measured" as follows:

hlegend=findobj(gcf,'Type','axes','Tag','legend');
legenddata=get(hlegend,'userdata');
legendstrings=legenddata.lstrings;
ii=find(strcmp('measured', legendstrings));
h_measured=legenddata.handles(ii);

I dont see how to do something similar with the new graphics handles system in R15. Any suggestions?

Answer 1

[Mike Garrity]

For your purposes here, I would think that the easiest is to use the DisplayName property on the objects. That matches the string that the legend is showing.

Consider this example:

%%Create a plot with a legend
plot(magic(5))
legend('first','second','third','fourth','fifth')

%%Get a handle to the legend
%
% The type has changed because legends are no longer axes.
%
l = findobj(gcf,'Type','legend')

%%Loop over the legend entries and set the linewidth of the corresponding object
%
% Our legend has five strings. Each line object has a DisplayName which
% matches one of those strings.
%
for ix=1:length(l.String)
  str = l.String{ix}
  h = findobj(gcf,'DisplayName',str);
  h.LineWidth = ix;
end

The result looks like this:

It looks like you might already know the DisplayName of the object you're looking for. If that's the case, you could skip getting the legend completely.

[Peter]

excellent. thanks Mike!

Answer 2

[Brendan Hamm]

The legend will no longer store this information unless you pass it to the UserData. I would suggest returning the objects created by your various graphics commands anytime you will need to access the data later.

f = figure;
ax = axes;
p = plot(randn(100,5)); % Make a plot of some random data
leg = legend('A','B','C','D','E'); % Create legend and return the object

leg.UserData = p; % We could assign the handles to the legend directly
idx = strcmp(leg.String,'B')
B = leg.UserData(idx) % returns the Line object
% We don't really need to store to the UserData.
Balt = p(idx); % Alternative without storage.

[Peter]

thanks Brendan, the thing is that for your solution i should have somehow stored the handles of the lines, which i didn't.