Multiple boxplot with unequal length in MATLAB - matlab

Question

Below is the MATLAB code that i used to plot multiple boxplots in one figure. However, this only works if the data is of equal length (n1,n2,n3,n4,n5,n6 =10 in this example). How do i change this so that it works for dataset with unequal length? For example: n1=10, n2=10, n3=15,n4=15,n5=5,n6=5?
clc
clear
n1=10;n2=10;n3=10;n4=10;n5=10;n6=10;
x=[rand(1,n1) rand(1,n2) rand(1,n3) rand(1,n4) rand(1,n5) rand(1,n6)];
n=10 ; xx=([1:6])'; % example
r=repmat(xx,1,n)';
g=r(:)';
positions = [1 2 3 4 5 6 ];
h=boxplot(x,g, 'positions', positions);
set(h,'linewidth',2)
set(gca,'xtick',[mean(positions(1:2)) mean(positions(3:4)) mean(positions(5:6)) ])
set(gca,'xticklabel',{'exp1','exp2','exp3'},'Fontsize',28)
color = ['c', 'y', 'c', 'y','c', 'y'];
h = findobj(gca,'Tag','Box');
for j=1:length(h)
patch(get(h(j),'XData'),get(h(j),'YData'),color(j),'FaceAlpha',.5);
end

Answer 1

clearvars
n1=10;n2=10;n3=15;n4=15;n5=5;n6=5;
A=zeros(n1,1);A=num2str(A);A(1:end)='1';
B=zeros(n1,1);B=num2str(B);B(1:end)='2';
C=zeros(n1,1);C=num2str(C);C(1:end)='3';
D=zeros(n1,1);D=num2str(D);D(1:end)='4';
E=zeros(n1,1);E=num2str(E);E(1:end)='5';
F=zeros(n1,1);F=num2str(F);F(1:end)='6';
x=[rand(1,n1) rand(1,n2) rand(1,n3) rand(1,n4) rand(1,n5) rand(1,n6)];
boxplot([x(1,1:n1)';x(1,n1+1:n1+n2)';x(1,n1+n2+1:n1+n2+n3)';x(1,n1+n2+n3+1:n1+n2+n3+n4)';...
x(1,n1+n2+n3+n4+1:n1+n2+n3+n4+n5)';x(1,n1+n2+n3+n4+n5+1:n1+n2+n3+n4+n5+n6)'],[A;B;C;D;E;F])

Answer 2

There are a couple issues with your code that cause it to fail. Check my code below which you should be able to replace with yours. Rather than having to specify n1,n2,...etc., put all n-values in an array. Note your set functions will not work if you change the number of elements in ns from 6, but my code on its own will. In the future, I suggest generalizing your code to be less dependent on such things, and define less variables.
ns=[20,7,16,5,6,7]; %rather than specifying all your n variables individually, put them in an array
x=rand(1,sum(ns(:))); %allocates membory for x
ns=[0,ns]; %used for easier indexing in for loop
for(i=2:length(ns))
g((1+sum(ns(1:(i-1)))):(ns(i)+sum(ns(1:(i-1)))))=repmat(i-1,1,ns(i)); % populates g array
end
positions=1:(length(ns)-1);
h=boxplot(x,g,'positions',positions)
or, if it makes more sense to you, you could replace
ns=[0,ns]; %used for easier indexing in for loop
for(i=2:length(ns))
g((1+sum(ns(1:(i-1)))):(ns(i)+sum(ns(1:(i-1)))))=repmat(i-1,1,ns(i)); % populates g array
end
with
g=[];
for(i=1:length(ns))
g=[g repmat(i,1,ns(i))];
end
though this is generally bad practice as the size of g changes with every loop,so Matlab may throw a warning if your ns get too big.