MATLAB: How to add errorbars

add errorbars

Dear all,

I want to add the errorbar for each bar, but it didn't work out.

The code I wrote is below

Can anyone fix it ? Thanks!

figure;
TGmatch=7.15;
AGmatch=8.32;
TGnonmatch=7.56;
AGnonmatch=7.84;
adRT=[TGnonmatch AGnonmatch;TGmatch AGmatch]; 
h=bar(adRT);
set(get(gca, 'YLabel'),'String','accuracy-adjusted RT (ms/%)','FontSize',14);
set(gca, 'FontSize',14,'XTick',[1 2],'XTickLabel',{'Nonmatch','Match' })
set(get(gca, 'Title'),'String','(C) visual-spatial attention','FontSize',16);
ylim([0 10]);
set(gca,'YTick',1:2:10);
TGmatchSE=.25;
AGmatchSE=.44;
TGnonmatchSE=.29;
AGnonmatchSE=.41;
errorbar(1,TGmatch,TGmatchSE,'k');
errorbar(1,AGmatch,AGmatchSE,'k');
errorbar(2,TGnonmatch,TGnonmatchSE,'k');
errorbar(2,AGnonmatch,AGnonmatchSE,'k');
set(gca, 'Box', 'off');
set(gca,'color','none');
legend('TG','AG','Fontsize',14);

Best Answer

You forgot to add hold on before calling errorbar so that wiped out the barplot and then each subsequent call to it also will have overwritten the previous. But, that alone won't solve your problem because with a grouped bar, the locations aren't in the center of the bars but at the center of each group. I've complained for 20+ years and TMW has yet to do anything really positive to solve the horrendous interface to bar and to provide easy ways to do the obviously-needed such as this; I would strongly suggest to add your voice to the complaints about quality of implementation being lacking and the need for the facility to be included as a standard set of options in one manner or another. OK, editorializing over, see

<Answers:379570-how-can-i-place-my-error-bar-in-separate-bar-center> for example of how to locate the positions and to do what you're asking for.

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MATLAB: Data labels above bars on grouped bar plot

You're on the right track, the center of each group is at the axis tick value. For each bar in the group, use that value plus/minus a delta to locate the x position for your text.

I did an example of this for another poster within the last few weeks at most altho I don't have the link at hand. Perhaps a search will uncover it.

ADDENDUM:

OK, I looked at past answers--this one is pretty close altho I thought I did another. Maybe it was in the newsgroup instead...

http://www.mathworks.com/matlabcentral/answers/127300-draw-a-specialized-bar-graph#answer_134750

MATLAB: How to change the color for bar graphs and create space between grouped bars

ABC=[ [10,13,9,6,20]' [2, 4, 7, 9,10]' [-2,-3,-8,-10,-11]'].';
hBar=bar(ABC,'grouped');      % basic grouped bar plot, keep handle
hFg=gcf; hAx=gca;             % handles to current figure, axes
ylim([-20 30])                % space out a little extra room
hAx.XTickLabel={'A';'B';'C'}; % label x axis
hAx.YColor=get(hFg,'color'); box off  % hide y axis/labels, outline
hLg=legend(num2str([2;5;10;20;25]), ...
           'orientation','horizontal', ...
           'location','north'); legend('boxoff') % add legend

yields

With more recent release than I have here (R2014b) you can also move the y-axis to the origin with

hAx.XAxisLocation='origin';

to essentially duplicate the example.

hBar(N).FaceColor='r';

would for example color the N th bar in the group red if don't like default colors (which, granted, aren't the most pleasing they could be).

ADDENDUM: OK, am back so to do error bars on the bar plot--

Start by combining the data into an array instead of using separate variables -- a general coding principle in Matlab, btw, makes things much more efficient as a rule.

ABCerr=[A_error;B_error;C_error];
x=repmat([1:size(ABC,1)].',1,size(ABC,2));  % bar x nominals
xOff=bsxfun(@plus,x,[hBar.XOffset]); % bar midpoints x
hold all                             % keep axis limits, etc.
hEB=errorbar(xOff,ABC,ABCerr,'.');   % add errorbars

Above will have a set of default colors for the errorbar series that won't necessarily coincide with the bar series already have.

I do not know where the default bar color series values are stored; the default 'FaceColor' value is the string 'Flat' which isn't of much help in matching to but as noted above you can reset it to either one of the eight defined color strings or any RGB triplet to match up with the default errorbar colors could be

for i=1:length(hBar)
  hBar(i).FaceColor=hEB(i).Color;
end

or choose a set for both. Or, on further reflection and looking at the plot created, maybe 'k' for all the error bars might help them be visible, particularly the lower limits that are in the bars.

Another fixup would be

hBar(1).BaseLine.Color='k';

to show the baseline under the bars; it follows the y-axis color by default so became invisible when turned that color to match the figure background.

Best Answer

Related Solutions

MATLAB: Data labels above bars on grouped bar plot

MATLAB: How to change the color for bar graphs and create space between grouped bars

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