Legend in bar plot

Hello,

I wanna create a legend for a bar plot but I always get a warning message and it only shows one entitie of the legend. Here is a minimal code example

X=categorical({'small','medium','large'});
X=reordercats(X,{'small','medium','large'});
Y=[5 18 56];
TestL={'Mon','Tue','Wed'};

figure()
b=bar(X,Y);
b.FaceColor = 'flat';
b.CData(1,:)=[1 0 0];
b.CData(2,:)=[0 1 0];
b.CData(3,:)=[0 0 1];
legend(TestL)

And this is what i get from Matlab

What is wrong here ? I´m totally confused.

Thanks

Answer 1

[dpb]

A somewhat different approach to Walter's to generate the three needed bar handles -- use a 'stacked' plot with the elements on the diagonal, zero for the off-diagonal elements. 'stacked' creates a bar for each row whose heights are each the sums of the elements on the row. (And, need 'stacked' because otherwise passing an array to bar causes it to draw a 'grouped' bar.)

hB=bar(X,diag(Y,0),'stacked');
hLg=legend(TestL,'Location','northwest');

with default color produces

The bars can be customized as desired through the array of bar handles hB.

[dpb]

Again, however, it illustrates just how klunky the bar() user interface is that one is forced to such chicanery.

[dpb]

set(hB,{'FaceColor'},{'r';'g';'b'})
hLg=legend(TestL,'Location','best')

will put where is least conflict with data -- if we do the above but swap the order to

hB=bar(flip(X),fliplr(diag(Y,0)),'stacked');
hLg=legend(TestL,'Location','best')

we get

where the legend has been moved automagically to the NE corner instead.

As an aside, I don't follow why this isn't the default legend behavior...

[René Lampert]

thanks for your help

Answer 2

[Walter Roberson]

legend() creates at most one entry for each graphics object. However, each call to bar() creates one graphics object, not one object for each group.

Create one extra bar() object for each item you want to legend(), and use nan as the data for that. legend() on those handles

X=categorical({'small','medium','large'});
X=reordercats(X,{'small','medium','large'});
Y=[5 18 56];
TestL={'Mon','Tue','Wed'};
figure()
b=bar(X,Y);
hold on
b.FaceColor = 'flat';
b.CData(1,:)=[1 0 0];
b.CData(2,:)=[0 1 0];
b.CData(3,:)=[0 0 1];
bh(1) = bar(nan,nan,'r');
bh(2) = bar(nan,nan,'g');
bh(3) = bar(nan,nan,'b');
legend(bh, string(X))

[René Lampert]

thanks for your fast response...is it also possible to put the legend at another place, for instance at top left corner?

[Walter Roberson]

X=categorical({'small','medium','large'});
X=reordercats(X,{'small','medium','large'});
Y=[5 18 56];
TestL={'Mon','Tue','Wed'};
figure()
b=bar(X,Y);
hold on
b.FaceColor = 'flat';
b.CData(1,:)=[1 0 0];
b.CData(2,:)=[0 1 0];
b.CData(3,:)=[0 0 1];
bh(1) = bar(nan,nan,'r');
bh(2) = bar(nan,nan,'g');
bh(3) = bar(nan,nan,'b');
legend(bh, string(X), 'location', 'northwest')

Answer 3

[Greg LANGE]

What should I change to have my "Tuesday" to have the same color as my bar ? (purple)

What should I do to have my label as my picture with coordonates ?

Thank you in advance

 figure (5)
 %modifié
 X=categorical({'small','medium','large'});
X=reordercats(X,{'small','medium','large'});
Y=[5 18 56];
TestL={'Mon','Tue','Wed'};
figure()
b=bar(X,Y);
hold on
b.FaceColor = 'flat';
b.CData(1,:)=[1 0 0];
%b.CData(2,:)=[0 1 0];
b.CData(2,:)=[0.4940 0.1840 0.5560];
b.CData(3,:)=[0 0 1];
bh(1) = bar(nan,nan,'r');
bh(2) = bar(nan,nan);%
bh(3) = bar(nan,nan,'b');
bh(2).CData=[0.4940 0.1840 0.5560];
legend(bh, TestL, 'location', 'best') %'northwest'

%legent at the top
  xtips1 = b(1).XEndPoints;
ytips1 = b(1).YEndPoints;
labels1 = string(b(1).YData);
text(xtips1,ytips1,labels1,'HorizontalAlignment','center',...
    'VerticalAlignment','bottom')

 ylabel('Energie [kWh]')