Show coordinates for a 2D point in a table cell

I'm working on a MATLAB app where I'm trying to dynamically record and show every mouse click on the UIAxes in a UItable.

My problem is that the table only shows "1x2 double" in the designated cell for the coordinates instead of the actual numbers.

Is this possible to fix or do I have to split them into two columns?

app.PointsTable.Data = table('Size',[0 2],'VariableNames', {'Point', 'Coordinates'}, 'VariableTypes', {'uint8', 'cell'});

function UIAxesButtonDown(app, event)
if 1
    coordinates = app.UIAxes.CurrentPoint(1, 1:2);
    numRows = size(app.PointsTable.Data, 1);
    app.PointsTable.Data(numRows+1, :) = {numRows+1, {[coordinates(1) coordinates(2)]}};
end
end

Answer 1

[Voss]

One way to display a vector in a single cell of a uitable is to make it into a string:

app.PointsTable.Data = table( ...
    'Size', [0 2], ...
    'VariableNames', {'Point', 'Coordinates'}, ...
    'VariableTypes', {'uint8', 'string'}); % string type now, not cell


function UIAxesButtonDown(app, event)
if 1
    coordinates = app.UIAxes.CurrentPoint([1 2]);
    numRows = size(app.PointsTable.Data, 1);
    app.PointsTable.Data(numRows+1, :) = {numRows+1, "[" + join(compose("%f",coordinates),",") + "]"}
end
end

[Quist]

Thanks! I had planned to also use the table as storage location of the data for further processing later. So then I have to do the reverse operation (text to vector), or perhaps it’s better to mirror the data also in a matrix, just using the table for UI purposes…

[Voss]

You're welcome!

Regarding the question of using the uitable for storage vs mirroring it, in my opinion:

1. if the user can edit the uitable (add/delete rows, modify cell contents), then use the uitable as the storage with no variable(s) mirroring its contents
2. if the user cannot edit the uitable, then use the variable(s) on which the uitable's contents are based when you need to access the data; if there are no such variables, then you'd need to implement them, or just use the uitable as storage (option 1)

In case you need it, here's an example showing one way to recover the numeric data from the strings in the uitable:

% a table variable:
app.PointsTable.Data = table( ...
    'Size', [0 2], ...
    'VariableNames', {'Point', 'Coordinates'}, ...
    'VariableTypes', {'uint8', 'string'});

% add five rows of random coordinates:
for ii = 1:5
    coordinates = rand(1,2);
    numRows = size(app.PointsTable.Data, 1);
    app.PointsTable.Data(numRows+1, :) = {numRows+1, "[" + join(compose("%f",coordinates),",") + "]"};
end

% show the table variable:
disp(app.PointsTable.Data)

    Point         Coordinates     
    _____    _____________________

      1      "[0.415212,0.448916]"
      2      "[0.409778,0.733798]"
      3      "[0.663416,0.919541]"
      4      "[0.610271,0.833671]"
      5      "[0.075813,0.838912]"

% get a numeric matrix of the coordinates:
F = @(s)str2num(s,'Evaluation','restricted');
C = arrayfun(F,app.PointsTable.Data.Coordinates,'UniformOutput',false);
M = vertcat(C{:});

% show the numeric matrix
format long g
disp(M)

                  0.415212                  0.448916
                  0.409778                  0.733798
                  0.663416                  0.919541
                  0.610271                  0.833671
                  0.075813                  0.838912