Kindly guide on how to connect the median points of boxplot with line and how to obtain respective colors of boxplot in the legend. Please help. Added the pot for reference.

CODE:

A1 = [36 38 39]';
B1 = [1 5 10]';
C1 = [-17 -11 -2]';
group = [    ones(size(A1));
         2 * ones(size(B1));
         3 * ones(size(C1))];

h1=boxplot([A1; B1; C1],group,'colors','b','widths',0.25,'BoxStyle','filled')
lines = findobj(gcf, 'type', 'line', 'Tag', 'Median');
set(lines, 'Color', 'g');
hold on

a3 = [27 30 36]';
b3 = [-26 -16 1]';
c3 = [-64 -47 -18]';
group = [    ones(size(a3));
         2 * ones(size(b3));
         3 * ones(size(c3))];
% figure
h2=boxplot([a3; b3; c3],group,'colors','r','widths',0.25,'BoxStyle','filled')
set(gca,'XTickLabel',{'1','3','5'})
lines = findobj(gcf, 'type', 'line', 'Tag', 'Median');
set(lines, 'Color', 'y');
hold on

a5 = [-14 1 35]';
b5 = [-152 -104 -3]';
c5 = [-274 -195 -26]';
group = [    ones(size(a5));
         2 * ones(size(b5));
         3 * ones(size(c5))];
% figure
h3=boxplot([a5; b5; c5],group,'colors','g','widths',0.25,'BoxStyle','filled')
set(gca,'XTickLabel',{'1','3','5'})
lines = findobj(gcf, 'type', 'line', 'Tag', 'Median');
set(lines, 'Color', 'y');
legend(findobj(gca,'Tag','Box'),'a','b','c')

Answer 1

[Adam Danz]

There are multiple ways to do this. Since you're already finding the median line objects, you could extract the coordinates from those lines (demonstrated below).

Otherwise, you could compute the medians directly from each group.

A1 = [36 38 39]';
B1 = [1 5 10]';
C1 = [-17 -11 -2]';
group = repelem((1:3)',[numel(A1);numel(B1);numel(C1)]);

h1=boxplot([A1; B1; C1],group,'colors','b','widths',0.15,'BoxStyle','filled');
lines = findobj(gcf, 'type', 'line', 'Tag', 'Median');
set(lines, 'Color', 'g','LineWidth',2);
hold on

xMed = mean(vertcat(lines.XData),2); % n x 1
yMed = vertcat(lines.YData); % n x 2 (duplicate columns)
plot(xMed, yMed(:,1), 'ro-')

[Swathi S]

Thank you for your response. I am getting multiple median lines. I just want a single line for each boxplot. Moreover, can you help with the legend color?

[Adam Danz]

That's because every time you call

lines = findobj(gcf, 'type', 'line', 'Tag', 'Median');

You're finding all of the median markers in the axes, not just the ones that belong to the group that was just added to the plot.

Instead, find the median markers that belong to the boxplot objects that were just added to the axes,

h1=boxplot([A1; B1; C1],group,'colors','b','widths',0.25,'BoxStyle','filled')
lines = findobj(h1, 'type', 'line', 'Tag', 'Median');
%               ^^

[Adam Danz]

legend([h1(2),h2(2),h3(2)])

[Swathi S]

I could get the appropriate median markers. Thank you for your guidance and immediate response.