Question on Plotting from Cell Array

Hi guys,

I have a 1000*10 cell array, where each cell is a 1*3 3D coordinate. A segment of this cell array is shown below:

The rows represent time in second, and each column represent location of an object, so each cell is an object's coordinate in space at a given second. There are 10 columns for 10 objects, and 1000 rows for 1000 seconds. I wish to create an animation of all these objects' locations in space from 1s to 1000s: how would I do that? The objects can just be scatter points in a MATLAB 3D plot. Thank you for your help!

GZ

Answer 1

[the cyclist]

% Parameters
NCOORD     =    3;
NT         = 1000;
NOBJ       =   10;
MARKERSIZE =   72;

% Pretend data
C = cell(NT,NOBJ);
C = cellfun(@(x)rand(1,NCOORD),C,'UniformOutput',false);

% Format into numerical array for convenience
coordByTimeByObject = reshape([C{:}],NCOORD,NT,NOBJ);

% Permute for plotting convenience
timeByObjectByCoord = permute(coordByTimeByObject,[2 3 1]);

% Preallocate the movie frames
M(NT).cdata    = [];
M(NT).colormap = [];

% Plot each time step
figure
for nt = 1:NT
    scatter3(timeByObjectByCoord(nt,:,1),timeByObjectByCoord(nt,:,2),timeByObjectByCoord(nt,:,3),MARKERSIZE,1:NOBJ);
    title(sprintf('Time point: %4d',nt))
    xlim([0 1])
    ylim([0 1])
    zlim([0 1])
    % Capture the movie frame
    M(nt) = getframe(gcf);
    clf
end

% Write the video file
v = VideoWriter('Watch the objects move.mp4','MPEG-4');
open(v)
writeVideo(v,M)
close(v)

Answer 2

[Matt J]

Points=reshape(   [CellArray{:}]  ,3,[],10);  %

for i=1:1000
    X=Points(1,i,:);
    Y=Points(2,i,:);
    Z=Points(3,i,:);
    scatter3(X(:),Y(:),Z(:)); drawnow
    
end

Answer 3

[dpb]

Dereference the cell array with the curlies "{}"

for i=1:size(CA,2)
  scatter3(CA{i}(:,1),CA{i}(:,2),CA{i}(:,3))
  if i==1,hold on, end
end

if the cell array is CA the above will put all on a single axis with cycled colors. Insert additional arguments for size or varied color map or whatever--"salt to suit".

Or, could create subplots of additional figure each pass, all just depends on the effect you're after.