There is no direct way of displaying boxplots for two different groups (in this example, observed and simulated temperatures) on the same figure.
As a workaround, boxplots can be generated at defined positions for one group first. HOLD ON allows the boxplots for the second group to display on the same figure.
In the following example, boxplots of the second group are 0.2 units away (user defined) from their corresponding blue boxplots.
% {Display boxplots for two different groups,
% observed and simulated temperatures from January to December on the same figure}%
close all
clc
data = textread('bp.txt'); % Read user’s data file
%{Assign the observed temperature to be Month_O and the simulated
% temperature to be Month_S}%
Jan_O = data(:, 1);
Jan_S = data(:, 2);
Feb_O = data(:, 3);
Feb_S = data(:, 4);
Mar_O = data(:, 5);
Mar_S = data(:, 6);
Apr_O = data(:, 7);
Apr_S = data(:, 8);
May_O = data(:, 9);
May_S = data(:,10);
Jun_O = data(:,11);
Jun_S = data(:,12);
Jul_O = data(:,13);
Jul_S = data(:,14);
Aug_O = data(:,15);
Aug_S = data(:,16);
Sep_O = data(:,17);
Sep_S = data(:,18);
Oct_O = data(:,19);
Oct_S = data(:,20);
Nov_O = data(:,21);
Nov_S = data(:,22);
Dec_O = data(:,23);
Dec_S = data(:,24);
f=figure;
% Boxplot for the observed temperature from January to December
Temp_O = [Jan_O, Feb_O, Mar_O, Apr_O, May_O, Jun_O, Jul_O, Aug_O, Sep_O, Oct_O, Nov_O, Dec_O];
position_O = 1:1:12;
% Define position for 12 Month_O boxplots
box_O = boxplot(Temp_O,'colors','b','positions',position_O,'width',0.18);
set(gca,'XTickLabel',{' '}) % Erase xlabels
hold on % Keep the Month_O boxplots on figure overlap the Month_S boxplots
% Boxplot for the simulated temperature from January to December
Temp_S = [Jan_S, Feb_S, Mar_S, Apr_S, May_S, Jun_S, Jul_S, Aug_S, Sep_S, Oct_S, Nov_S, Dec_S];
position_S = 1.3:1:12.3; % Define position for 12 Month_S boxplots
box_S = boxplot(Temp_S,'colors','r','positions',position_S,'width',0.18);
hold off % Insert texts and labels
ylabel('Temperature')
text('Position',[1.1,0],'String','January')
text('Position',[2.1,0],'String','February')
text('Position',[3.1,0],'String','March')
text('Position',[4.1,0],'String','April')
text('Position',[5.1,0],'String','May')
text('Position',[6.1,0],'String','June')
text('Position',[7.1,0],'String','July')
text('Position',[8.1,0],'String','August')
text('Position',[9.1,0],'String','September')
text('Position',[10.1,0],'String','October')
text('Position',[11.1,0],'String','November')
text('Position',[12.1,0],'String','December')
set(gca,'XTickLabel',{''}); % To hide outliers
out_O = box_O(end,~isnan(box_O(end,:)));
delete(out_O)
out_S = box_S(end,~isnan(box_S(end,:)));
delete(out_S)
