How to add space between group of box and whisker bars using boxchart?

I have data from 4 subjects. I want to add gaps between the red, blue and green bars of each subject using boxchart. Any recommendations would be great!

tbl = MasterData

tbl.SubjectID = categorical(tbl.SubjectID)

Display_Type = {"R","L"};

tbl.TargetDisplay = categorical(tbl.TargetDisplay);

idx = (tbl.TargetDisplay == "L")

tbl_Left_Display = tbl(idx,:)

figure(2);

title('Box and Whisker Plots for Display "L"');

boxchart(tbl_Left_Display.SubjectID,tbl_Left_Display.HorizontalFinalOffset,'GroupByColor',tbl_Left_Display.Color,'Notch','on','BoxWidth',1)

colororder([0 0 1;0 1 0; 1 0 0])

ylim([-8,8])

ylabel('Horizontal Final Offsets')

legend

Example data:

Color HorizontalFinalOffset TargetDisplay SubjectID

_____ _____________________ _____________ _________

{'B'} -1.4175 {'L'} {'JD'}

{'R'} -2.0716 {'L'} {'JD'}

{'G'} 0 {'L'} {'JD'}

{'R'} 2.4858 {'R'} {'JD'}

{'B'} -0.19851 {'R'} {'JD'}

{'G'} 0 {'R'} {'JD'}

{'R'} -2.4937 {'L'} {'JD'}

{'B'} -0.97587 {'L'} {'JD'}

{'G'} 0 {'L'} {'JD'}

{'R'} -0.66174 {'L'} {'JD'}

Answer 1

[Voss]

First, I make table variables like yours:

d = {'R';'L'};
s = {'JD';'MM';'SH';'YL'};
c = {'B';'G';'R'};
Npts = 1000;

Color = c(randi(numel(c),Npts,1));
HorizontalFinalOffset = 2*randn(Npts,1);
TargetDisplay = d(randi(numel(d),Npts,1));
SubjectID = s(randi(numel(s),Npts,1));
tbl = table(Color,HorizontalFinalOffset,TargetDisplay,SubjectID);

tbl.SubjectID = categorical(tbl.SubjectID);
tbl.TargetDisplay = categorical(tbl.TargetDisplay);
idx = (tbl.TargetDisplay == "L");
tbl_Left_Display = tbl(idx,:)

tbl_Left_Display = 502×4 table
    Color    HorizontalFinalOffset    TargetDisplay    SubjectID
    _____    _____________________    _____________    _________

    {'G'}             1.3382                L             YL    
    {'G'}             2.2871                L             MM    
    {'B'}             1.4812                L             YL    
    {'B'}             2.0882                L             YL    
    {'B'}          -0.053404                L             SH    
    {'G'}            -0.9785                L             MM    
    {'G'}            -1.0104                L             YL    
    {'B'}            0.63819                L             YL    
    {'R'}           -0.82647                L             MM    
    {'R'}             1.4959                L             YL    
    {'R'}            -1.5126                L             SH    
    {'R'}           -0.21446                L             YL    
    {'B'}            -2.5901                L             MM    
    {'G'}             2.9614                L             SH    
    {'G'}            -1.3147                L             YL    
    {'G'}            -1.7271                L             SH    

The boxchart, as you have it already:

figure()
b = boxchart(tbl_Left_Display.SubjectID,tbl_Left_Display.HorizontalFinalOffset,'GroupByColor',tbl_Left_Display.Color,'Notch','on','BoxWidth',1);
colororder([0 0 1; 0 1 0; 1 0 0])
ylim([-8,8])
ylabel('Horizontal Final Offsets')
legend

Now, modifying the gaps between the boxcharts:

Option 1: decreasing 'BoxWidth':

figure()
b = boxchart(tbl_Left_Display.SubjectID,tbl_Left_Display.HorizontalFinalOffset,'GroupByColor',tbl_Left_Display.Color,'Notch','on','BoxWidth',0.5);
colororder([0 0 1; 0 1 0; 1 0 0])
ylim([-8,8])
ylabel('Horizontal Final Offsets')
legend

Option 2: manually setting the XData (adjust as desired):

[s,~,xx] = unique(tbl_Left_Display.SubjectID);
ns = numel(s);
c = {'B';'G';'R'};
nc = numel(c);
figure()
hold on
if nc > 1
    offset = 1/max(3,7-nc);
    offset = linspace(-offset,offset,nc);
else
    offset = 0;
end    
width = 1/(2*nc);
for ii = 1:nc
    idx = strcmp(tbl_Left_Display.Color,c{ii});
    y = tbl_Left_Display.HorizontalFinalOffset(idx);
    x = xx(idx)+offset(ii);
    boxchart(x,y,'Notch','on','BoxWidth',width);
end
colororder([0 0 1; 0 1 0; 1 0 0])
xlim([0.5 ns+0.5])
xticks(1:ns)
xticklabels(s)
ylim([-8,8])
ylabel('Horizontal Final Offsets')
legend(c)

[MM]

Thank you, the second approach was exactly what I needed!

[Voss]

You're welcome!