MATLAB: Data labels above bars on grouped bar plot

barplotgroupedtext labels

I'm making a grouped bar plot (i.e., a bar plot with multiple bars in each category). I would like to add labels at the top of each bar to indicate its height. I was planning to just use the text function. However, bars within a given group all have the same x location (i.e get(h,'XData') is the same for all bar series). I'm not sure how to find the proper x location for each bar within a given group. Any ideas?

Thanks, Justin

Best Answer

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

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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.

MATLAB: How to label the grouped horizontal bars in MATLAB

I solved adding this code:

yb = [datas{2,2}, datas{3,2}, datas{5,2}, datas{1,2}, datas{4,2}];
for j = 1:size(yb,2)
    text(yb(1,j)-0.1,j, cellstr(num2str(yb(1,j),'%0.2f%%')), 'HorizontalAlignment','right','VerticalAlignment','top','FontSize',15);
end
yb = [datas{2,3}, datas{3,3}, NaN, datas{1,3}, NaN];
for j = 1:size(yb,2)
    text(yb(1,j)+0.1,j+0.27, cellstr(num2str(yb(1,j),'%0.2f%%')), 'HorizontalAlignment','left','VerticalAlignment','top','FontSize',15);
end

Best Answer

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