Scatter3 : How do I add 4th variable to Data Tips?

I have this code going :

h=scatter3(Lab(2,:),Lab(3,:),Lab(1,:),80,RGB,'fill');

xlabel('b*'),ylabel('a*'),zlabel('L*');

title('CIE-L*a*b* coordinates');

axis([min_Lab(3) max_Lab(3) min_Lab(2) max_Lab(2) min_Lab(1) max_Lab(1)]);grid on;hold on;

% draw black lines indicating axis

line([min_Lab(3) max_Lab(3)],[0 0],[0 0],'color',[0 0 0],'lineWidth',linewidth); % Axis L* == a* == 0

line([0 0],[min_Lab(2) max_Lab(2)],[0 0],'color',[0 0 0],'lineWidth',linewidth); % Axis L* == b* == 0

line([0 0],[0 0],[min_Lab(1) max_Lab(1)],'color',[0 0 0],'lineWidth',linewidth); % Axis a* == b* == 0

% Redefine labels

h.DataTipTemplate.DataTipRows(1).Label = 'b';

h.DataTipTemplate.DataTipRows(2).Label = 'a=';

h.DataTipTemplate.DataTipRows(3).Label = 'L=';

h.DataTipTemplate.DataTipRows(3).Label = 'DE76='; <------ 4th Variable here!

% Show datatip

datatip(h, h.XData(1),h.YData(1),h.ZData(1));

I would like to add a fourth variable to the Data Tip as shown below :

Now, somehow (?), I need to pass the DE76 variable as argument to the datatip() function?

The problem, as I see it, is that datatip seem to only take its arguments from the figure handle, h :

datatip(h, h.XData(1),h.YData(1),h.ZData(1));

How could I possibly access my DeltaE variable, which is sitting in a different array :

DE76 =

0.2309 6.5948 6.3132

20.8147 15.0842 2.2396

0.7225 41.3219 55.9979

1.2122 0.9848 4.2285

I was thinking of, perhaps, adding a fourth row to the LabEpson array which would only contains Lab values otherwise. But they wouldn't be part of the "figure" h structure? This is where I'm lost...

I'll try to find the answer on my own...

Answer 1

[Cris LaPierre]

See the Create Custom Data Tips page.

[Roger Breton]

So the answer is to change the source of the scatter3 plot? By transfering my data into a Table variable to which I can add the DeltaE values, and specify the source of scatter3 accordingly, like :

tbl = readtable(myData);

s = scatter(tbl.L,tbl.a, tbl.b, tabl.DeltaE, ...);

dt = datatip(s,64,142);

Is 64,142 the row and colum size of the table?

[Cris LaPierre]

In the example you copied the code from, (64,142) corresponds to the (x,y) coordinates of the datapoint the tip will be shown for.

To create a solution, we need to know how DE76 relates to X,Y and Z values in the scatter plot. Ideally, all 4 are vectors of the same length.

Consider the following sample code, where all four variales are vectors with 12 elements.

Lab = rand(3,12);
DE76 = [0.2309    6.5948    6.3132
   20.8147   15.0842    2.2396
    0.7225   41.3219   55.9979
    1.2122    0.9848    4.2285];

h=scatter3(Lab(2,:),Lab(3,:),Lab(1,:),80,parula(length(Lab)),'fill');

xlabel('b*'),ylabel('a*'),zlabel('L*');
title('CIE-L*a*b* coordinates');

h.DataTipTemplate.DataTipRows(1).Label = 'b'; 
h.DataTipTemplate.DataTipRows(2).Label = 'a='; 
h.DataTipTemplate.DataTipRows(3).Label = 'L='; 
row = dataTipTextRow('DE76=',DE76(:));
h.DataTipTemplate.DataTipRows(end+1) = row;

datatip(h, h.XData(1),h.YData(1),h.ZData(1));

[Roger Breton]

I'm almost there.

This is my updated code with your two lines added :

% Redefine labels

h.DataTipTemplate.DataTipRows(1).Label = 'b';

h.DataTipTemplate.DataTipRows(2).Label = 'a=';

h.DataTipTemplate.DataTipRows(3).Label = 'L=';

row = dataTipTextRow('DE76=',DE76(:));

h.DataTipTemplate.DataTipRows(end+1) = row;

% Show datatip

datatip(h, h.XData(1),h.YData(1),h.ZData(1));

[Roger Breton]

Sorry, I had to continue here...

Then I got this result :

See?

It is perfect for points lieing outside the 3D volume only?

Is there an option to change this behavior?

[Cris LaPierre]

Sorry, change what behavior?

[Roger Breton]

I am well aware I could always "reason" that, if the 4th element, DeltaE is not being shown when mousing over the point then it's most likely that the color is in gamut and it's DeltaE value would most likely be zero, anyway.

Just curious if such thing would be possible. It maybe a simple option? Otherwise, I'm going to pass on this one and instead concentrate on my next strategy :-)

THANK YOU SO MUCH FOR YOUR INVALUABLE HELP AND PATIENCE!

[Cris LaPierre]

I don't understand the specifics of the data in your plot, but data tips correspond to actual datapoints in the axes. They should not appear where there is no data. Since DE76 must be the same length as the data on X, Y, and Z, you should always have data for all 4 rows of the data tip.

Your code has changed the datatip template, so that, in this figure, it will always have 4 rows. If there is an (X,Y,Z) datapoint that should not have a DE76 value, you could make that element's value in DE76 be NaN.