Plotting 4d data with matrices.

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Naty S
Naty S on 19 Aug 2013
Edited: chetan desai on 5 Apr 2015
Hey all, I am trying to plot a 4d plot( meaning 3 axis and 1 color) , I have looked at scatter3, mesh ,plot4d etc. but i was having trouble because part of my data is matrices. I am attaching the code below. To summaries my problem I have got: # Vx-[1*N]; # Vy-[1*N], # cont(:,:,1)-[N*N], # cont(:,:,2)-[N*N] What i want to get is a surface with Vx,Vy,cont(:,:,1) which colors change according to cont(:,:,2) any ideas how to do that? Thanks a lot! Naty
clc
clear all
close all
syms Vy Vx g theta1 r0 t theta0 d sigma eps sign
V0=[Vx,Vy];
t_impact=(d-r0*cos(theta0)-r0*cos(theta1))/Vx;
V_impact_minus=[Vx;Vy-g*t_impact];
R=[cos(theta1+pi/2) -sin(theta1+pi/2);sin(theta1+pi/2) cos(theta1+pi/2)];% Transformation Matrix
V_impact_P_Pre=R.'*V_impact_minus;% Transfrom from X,Y to Tanginet,Normal
V_impact_P_Post=[V_impact_P_Pre(1);-eps*V_impact_P_Pre(2)+sigma];
V_impact_plus=(R*V_impact_P_Post);
%Numerical Expression
m=1.548;
r0=0.193;
g=1.478;
theta0=pi/4;
Vx_target=-1;
Vy_target=0; % Fixed Ponint Valus.
eps=.7;
d=0.54;
N=10;
Vx_vec=linspace(-3,-0.1,N);
Vy_vec=linspace(-2,2,N);
% theta1=cont(1);
% sigma=cont(2);
cont=zeros(N,N,2);
for ii=1:length(Vx_vec)
for jj=1:1:length(Vy_vec)
Vx=Vx_vec(ii);
Vy=Vy_vec(jj);
myfun=matlabFunction(subs(V_impact_plus'-[Vx_target;Vy_target]'));
[cont(ii,jj,:),fval(ii,jj,:)]=fsolve(@(x) call_on(myfun, x),pi/3,0.3]);
end
end
[X,Y]=meshgrid(Vx_vec,Vy_vec);
scatter3(X(:),Y(:),cont(:,:,1))
  1 Comment
Sven
Sven on 19 Aug 2013
Please make sure your code is copy/paste runnable. At the moment there is an extra ] in your fsolve arguments, and after removing that I get the error:
Undefined function 'call_on' for input arguments of type 'function_handle'.
Error in @(x)call_on(myfun,x)
Error in fsolve (line 218)
fuser = feval(funfcn{3},x,varargin{:});

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Accepted Answer

Sven
Sven on 19 Aug 2013
Naty, as per the comment above I can't replicate your exact data, but here's an example that should show you how to make the figures you're looking for.
% Make some 4D data in X, Y, height, colour:
% Each point now has an X, Y, Z (height), and C (colour) value
[X,Y,Z] = peaks(51); % 51-by-51 Z as a function of X, Y
C = membrane(1,25); % Colour
% Show the data as a surface plot
figure, surf(X,Y,Z,C), colorbar
% Show the data as a scatter3 plot
figure, scatter3(X(:),Y(:),Z(:),6,C(:),'filled'), colorbar
So, according to your problem description:
What i want to get is a surface with Vx,Vy,cont(:,:,1).
Which colors change according to cont(:,:,2) any ideas how to do that?
You can just do this:
[X,Y]=meshgrid(Vx_vec,Vy_vec);
Z = cont(:,:,1);
C = cont(:,:,2);
And then just call syntax like my example above:
figure, surf(X,Y,Z,C), colorbar
figure, scatter3(X(:),Y(:),Z(:),6,C(:),'filled'), colorbar
Did that solve it for you?

More Answers (2)

francesco
francesco on 8 Nov 2013
great, is it possible to sum two plots?

chetan desai
chetan desai on 5 Apr 2015
Edited: chetan desai on 5 Apr 2015
what should be done if i am having C as a 3d matrix in above case ??

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