# 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.

19 views (last 30 days)
Swathi S on 22 May 2021
Commented: Swathi S on 23 May 2021
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')

Adam Danz on 22 May 2021
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 on 23 May 2021
I could get the appropriate median markers. Thank you for your guidance and immediate response.