Add error bars in bar graph

Hi! I am trying to add the error bars in my chart but I do not know how to do it...

>> y = [9862.5 5238 3845.2; 9368.6 3515 3625.7; 11064 6810 4073.6; 12599.2 5701 3955.3; 10114.4 5683 3664.5];
>> b = bar(y,'FaceColor', 'flat');
>> set (gca, 'XTickLabel',{ 'Pronghorn', 'Settler CL', 'Robidoux', 'LCS Chrome', 'Warhorse'})
>> for k = 1:size(y,2)
b(k).CData = k;
end;

this is the code for my chart.

And these are the std error:

1699.5 , 612.157 , 548.048 

Thank you!

[Adam Danz]

Here are some demos to follow

• https://www.mathworks.com/matlabcentral/answers/420926-bar-plot-with-error-bar
• https://www.mathworks.com/matlabcentral/answers/486175-how-can-i-change-colors-and-generate-errorbars-in-a-bar-graph
• https://www.mathworks.com/matlabcentral/answers/491212-error-bar-with-ci-95-on-bar-graph

[Luana Machado Simao]

I tried one of the codes but that is what happen:

>> count = [9862.5 5238 3845.2; 9368.6 3515 3625.7; 11064 6810 4073.6; 12599.2 5701 3955.3; 10114.4 5683 3664.5]; 
errLim = [1699.5 612.157 548.048]; 
err  = errLim - count; 
figure;
bar(count)
hold on
errorbar(1:length(count), [9862.5 5238 3845.2; 9368.6 3515 3625.7; 11064 6810 4073.6; 12599.2 5701 3955.3; 10114.4 5683 3664.5], err(1,:), err(2,:), 'LineStyle','none')
set(gca, 'xtick', 1:length(count), 'xticklabel', {'Pronghorn', 'Settler CL', 'Robidoux', 'LCS Chrome', 'Warhorse'});
Error using errorbar>checkSingleInput (line 270)
XData must be the same size as YData.

Error in errorbar (line 94)
x = checkSingleInput(x, sz, 'XData');
 
>> end;

Answer 1

[Adam Danz]

Here's a demo you can follow to add error bars to a grouped bar chart.

To center the errorbar on each bar, you need to compute their center points along the x axis.

In Matlab R2019B or later the bar center points are stored in

h = bar(__);

h.XEndPoints % x centers

Prior to Matlab R2019B, use an undocumented property XOffset explained here.

Required inputs are

• count: an n x m matrix that will produce n groups each containing m bars.
• err: an n x m matrix that defines the error for each bar

% Create bar data
count = [9862.5 5238 3845.2; 9368.6 3515 3625.7; 11064 6810 4073.6; 12599.2 5701 3955.3; 10114.4 5683 3664.5]; 

% Create error data (using random data for this demo)
err  = (rand(size(count))+2)*100; 

% Plot bars
figure;
h = bar(count);

% Get x centers; XOffset is undocumented
xCnt = (get(h(1),'XData') + cell2mat(get(h,'XOffset'))).'; 

% Add errorbars
hold on
errorbar(xCnt(:), count(:), err(:), err(:), 'k', 'LineStyle','none')
% or
% errorbar(xCnt(:), count(:), err(:), 'LineStyle','none')

Alternatively, if you're working with error intervals that define the upper and lower bounds of error,

Required inputs are

• count: an n x m matrix that will produce n groups each containing m bars.
• errUpperBound: an n x m matrix that defines the upper bound of error for each bar
• errLowerBound: an n x m matrix that defines the lower bound of error for each bar

% Create bar data
count = [9862.5 5238 3845.2; 9368.6 3515 3625.7; 11064 6810 4073.6; 12599.2 5701 3955.3; 10114.4 5683 3664.5]; 

% Create upper and lower error bounds
errUpperBound = count + 200; 
errLowerBound = count - 100; 

% Compute the error distance in the neg & pos directions
errNeg = count - errLowerBound; 
errPos = errUpperBound - count; 

% plot error bar
errorbar(xCnt(:), count(:), errNeg(:), errPos(:), 'k', 'LineStyle','none')

[Luana Machado Simao]

I am having some issues in adding my std errors in this section:

% Create error data (using random data for this demo)

err = (rand(size(count))+2)*100;

Thank you so much for the help!

[Adam Danz]

I don't know what problems you're having unless you tell me.

In your question, you only list 3 error values. It's not clear how 3 error values should be applied to 15 bars.

[Luana Machado Simao]

Sorry I didn't see my mistake there. So I have the 15 bars:

count = [9862.5 5238 3845.2; 9368.6 3515 3625.7; 11064 6810 4073.6; 12599.2 5701 3955.3; 10114.4 5683 3664.5];

So, for example, for "9862.5", the error range is: 6240.0 to 13485.0

for "5238": 3933.2 to 6542.8

and so on...

how can I add this values for each bar in this line?

err = (rand(size(count))+2)*100;

thank you! :)

[Adam Danz]

See the bottom of my updated answer.