How to draw a line in a bar chart in complete x area

Is there a way to make the horizontal line start from the very left and go to the very right? It's only going from the first x-marker to the last x-marker.

my code:

cat=categorical({'a','b','c'})

data = [37.6 24.5 14.6]';
errhigh = [2.1 4.4 0.4];
errlow  = [4.4 2.4 2.3];

bar(cat,data)                

hold on

er = errorbar(cat,data,errlow,errhigh);    
er.Color = [0 0 0];                            
er.LineStyle = 'none';  

hold off

line(xlim,[20 20])

output diagramm:

Thanks.

Answer 1

[Voss]

cats=categorical({'a','b','c'})

cats = 1x3 categorical array
     a      b      c 

data = [37.6 24.5 14.6]';
errhigh = [2.1 4.4 0.4];
errlow  = [4.4 2.4 2.3];

bar(cats,data)                

hold on

er = errorbar(cats,data,errlow,errhigh);    
er.Color = [0 0 0];                            
er.LineStyle = 'none';  

hold off

% force graphics to update so XLim is accurate
drawnow()

% prevent auto-updating of XLim when new line is made
set(gca(),'XLimMode','manual')

% make the new line
line([0 numel(cats)+1],[20 20])

I changed the variable cat to cats, since cat is the name of an important built-in function.

[Richard]

I tried your code. It still gives me the line only from the middle of the bars.

Is there a setting or something for this?

[Voss]

The line goes all the way across when I run it on my desktop (R2023b). See below:

Answer 2

[Star Strider]

The easiest option is to use the yline function —

cat=categorical({'a','b','c'})

data = [37.6 24.5 14.6]';
errhigh = [2.1 4.4 0.4];
errlow  = [4.4 2.4 2.3];

bar(cat,data)                

hold on

er = errorbar(cat,data,errlow,errhigh);    
er.Color = [0 0 0];                            
er.LineStyle = 'none';  

hold off

yline(20)                                           % Use 'yline' 

The Run feature is not working for some reason just now, ot it woudl be possible to demonstrate this here.

.

[Richard]

Thank you. Is there a different method? I want to make the line only appear in certain areas of x-values.

[Star Strider]

My pleasure!

You can do something like this —

cat=categorical({'a','b','c'})

data = [37.6 24.5 14.6]';
errhigh = [2.1 4.4 0.4];
errlow  = [4.4 2.4 2.3];

bar(cat,data)                

hold on

er = errorbar(cat,data,errlow,errhigh);    
er.Color = [0 0 0];                            
er.LineStyle = 'none';  

% plot([0 1], [1 1]*20)                       % Added

plot([0 1; 2 3; 4 5].', ones(3,2).'*20)     % All-In-One

hold off

however the placement requires a bit of experimentation, since numeric values of the ‘x’ axis aren’t precisely defined here. (The return from an xlim call is [a c] for example.) If you want them all on the same y-value, you can combine them as in the ‘All-In-One’ plot call, otherwise, it might be easier to use separate plot calls, similar to the commented-out version.

.