MATLAB graph plotting: assigning legend labels during plot

Question

I am plotting data in a typical MATLAB scatterplot format. Ordinarily when plotting multiple datasets, I would use the command \'hold on;\', and then plot each of the data,

Answer 1

One option is to take advantage of the 'UserData' property like so:

figure;
hold on
plot([0 1], [1 0], '-b', 'userdata', 'blue line')
plot([1 0], [1 0], '--r', 'userdata', 'red dashes')

% legend(get(get(gca, 'children'), 'userdata'))                      % wrong
legend(get(gca, 'children'), get(get(gca, 'children'), 'userdata'))  % correct

Edit: As the questioner pointed out, the original version could get out of order. To fix this, specify which handle goes with which label (in the fixed version, it is in the correct order).

Answer 2

You should be able to set the DisplayName property for each plot:

figure
hold on
plot(...,'DisplayName','DataSet1')
plot(...,'DisplayName','DataSet2')
legend(gca,'show')

http://www.mathworks.com/help/matlab/ref/line_props.html

Side Note: I've found a lot of little tricks like this by getting the figure to look the way I want, then choosing the Figure's "File" menu option "Generate M-File..." and inspecting the generated output code.

Answer 3

Make a for loop. But Before the for loop, make an array.

%for example 

legendset = {}

for i = 1:10 

%blabla
%Then in the fore loop say: 

legendset = [legendset;namedata(i)]

%It puts all names in a column of legendset. 
%Make sure namedata are characters. 

%foreloop ends
end

%Then after the foreloop say: 

legend(legendset). 

Answer 4

You can try something like the following

for k = 1:10

   h(k) = plot(...);
   name{k} = ['condition ' num2str(k)];

end

legend(h, name);

Answer 5

Use 'DisplayName' as a plot() property, and call your legend as

legend('-DynamicLegend');

My code looks like this:

x = 0:h:xmax;                                  %// get an array of x-values
y = someFunction;                              %// function
plot(x, y, 'DisplayName', 'Function plot 1');  %// plot with 'DisplayName' property

legend('-DynamicLegend',2);                    %// '-DynamicLegend' legend

Source: http://undocumentedmatlab.com/blog/legend-semi-documented-feature/