I'm using Matlab 2021a. My case use is a bit different than most here but thinking this might prove useful to someone. I am plotting data in a loop, and want the size of the marker in the legend to match the markersize on the scatter plot. I only wanted certain entries to show up in the legend to avoid repetition (in this case, markersize is determined by year).
Note that this does throw warnings, but still seems to work.
Most relevant code for setting legend marker size is marked by %------> <------%
%create data structure -- 3 measurements at 3 locations over multiple years
x = linspace(1,10,12);
y = linspace(0,1,12);
z = linspace(-4,0,12);
names = ['a';'b';'c';'a';'b';'a';'b';'a';'b';'c';'a';'b']; %data
years = [1990,1990,1990,1992,1992,1995,1995,2000,2000,2000,2005,2005]; %data
for i = 1:length(x)
struct(i).x= x(i);
struct(i).y= y(i);
struct(i).z= z(i);
struct(i).name = names(i);
struct(i).year = years(i);
end
%create markersize structure based on year
uyrs = unique([struct.year]); %array of unique years
sz = linspace(10,35,length(uyrs)); %array of sizes, same length as year
for i=1:length(uyrs)
szplot(i).year = uyrs(i);
szplot(i).sz = sz(i);
end
%create color structure based on name
uname = unique({struct.name}); %array of unique names
cols = ['#8c510a';'#fc8d59';'#d8b365'];
for i=1:length(uname)
cplot(i).name = uname{i};
cplot(i).color = cols(i,:);
end
%%
n=1; %keeps track of number of years
figure; tiledlayout(1,2);
for ind=1:length(struct)
nexttile(1)
hold on;
if strcmp(struct(ind).name,'a') %conditional for x data I want to show in legend (1 per year)
cc = cplot(matches({cplot.name},struct(ind).name)).color; %finds correct color based on conditional
size = szplot(n).sz;
year = szplot(n).year;
p1(n) = scatter(struct(ind).x,struct(ind).y,size,'MarkerFaceColor',cc,'DisplayName',num2str(year)); %by giving it a handle (p1) & DisplayName, ensures desired labeled data shows up in legend
n=n+1; %keeps track of number of years
end
cc = cplot(matches({cplot.name},struct(ind).name)).color; %matches color to name
size = szplot([szplot.year]==struct(ind).year).sz; %matches size to year
scatter(struct(ind).x,struct(ind).y,size,'MarkerFaceColor',cc); %plot rest of x data
nexttile(2)
hold on;
scatter(struct(ind).z,struct(ind).y,size,'MarkerFaceColor',cc); %plot z data
drawnow;
%------> <------%
if ind==length(struct)
[lg1,obj]=legend(p1,'Orientation','Horizontal'); %creates obj to find marker size at end of plotting
end
%------> <------%
end
%------> <------%
objhl = findobj(obj, 'type', 'patch'); % finds objects in legend of type patch (e.g. marker)
for i = 1:length(objhl) %iterate through patches to set each size individually
set(objhl(i), 'Markersize', sqrt(szplot(i).sz)); % set marker size according to size structure
end
%------> <------%
lg1.Layout.Tile = 'North';
