Grouped boxplot plots with different lengths and colors in different categories

Hello,

I am currently plotting three different arrays, with different length each, on the same figure using BOXPLOT. Here is currently the code that I am using (sorry for not providing a running example, I am actually loading external data):

% Load the data
x1 = ARRAY1;
x2 = ARRAY2;
x3 = ARRAY3;

% Grouping the data to plot on the same figure
group = [    ones(size(x1));
         2 * ones(size(x2));
         3 * ones(size(x3))];

% Plotting
% Define the color order
colors = [0 0.4470 0.7410;0.8500 0.3250 0.0980;0.9290 0.6940 0.1250];
% Plot
boxplot(X, group, 'BoxStyle','outline','Colors',colors, 'Symbol', '.');
% Fill the plots according to the color defined
h = findobj(gca,'Tag','Box');
for j=1:length(h)
    patch(get(h(j),'XData'),get(h(j),'YData'),get(h(j),'Color'),'FaceAlpha',.3);
end

When running this code, I get the following figure:

I would like to do two things:

1. Firstly, all the plots in these figure to be under the same category in the "X" axis.
2. Secondly, to add to the same more figure, three more boxes, which are defined by arrays with different length, to the same figure but in another category.

The end result, I would be expecting something like this:

Thanks!

[Clay Swackhamer]

Regarding your two questions, this code should show how to approach question 1. For question 2, try modifying the line "group" so that it is like this:

group = [1,1,1, 2,2,2, 3,3,3, 4,4,4, 5,5,5,5, 6,6,6,6];

That makes it so there are three data points in group 1, 2, 3, and 4, but four data points in group 5 and 6, and it doesn't create any issue in the plot.

%%  box_plot_groups
clear
close all

% Generate example data
group = [1,1,1, 2,2,2, 3,3,3, 4,4,4, 5,5,5, 6,6,6];

for i=1:numel(group)
    y(i) = group(i).*rand(1);
end

% Set x axis positions of the groups
positions = [1,1.25,1.5, 2,2.25,2.5];

% Make plot
boxplot(y,group, 'positions', positions, 'Symbol', '', 'Whisker', inf)

% Create axis labels
set(gca,'xtick',[ mean(positions(1:3)), mean(positions(4:end))])
set(gca,'xticklabel',{'Category 1', 'Category 2'})

Answer 1

[Voss]

One way:

x1 = randn(10,1);
x2 = randn(10,1);
x3 = randn(10,1);

y1 = randn(100,1);
y2 = randn(50,1);
y3 = randn(20,1);

X = [x1;x2;x3];
Y = [y1;y2;y3];

groupX = [    ones(size(x1));
          2 * ones(size(x2));
          3 * ones(size(x3))];
groupY = [    ones(size(y1));
          2 * ones(size(y2));
          3 * ones(size(y3))];

% Define the color order
colors = [0 0.4470 0.7410;0.8500 0.3250 0.0980;0.9290 0.6940 0.1250];

data = {X,Y};
groups = {groupX,groupY};

N_categories = numel(data);

offset = [-0.25, 0, 0.25];

for ii = 1:N_categories
    
    % Plot
    h = boxplot(data{ii},groups{ii}, ...
        'BoxStyle','outline', ...
        'Colors',colors, ...
        'Symbol','.', ...
        'Widths',0.2, ...
        'Positions',ii+offset);
    
    % Fill the plots according to the color defined
    for j=1:size(h,2)
        patch(get(h(5,j),'XData'),get(h(5,j),'YData'),get(h(5,j),'Color'),'FaceAlpha',.3);
    end
    
    hold on
    
end

xlim([0.5 N_categories+0.5])
xticks(1:N_categories)
xticklabels("Category "+(1:N_categories))

[Naos]

Thanks. It is working perfectly.

[Voss]

You're welcome!