# How can I have the numbers in one vector after a while loop?

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Ang Vas on 10 Jun 2015
Edited: Stephen23 on 10 Jun 2015
Let say that I have a matrix A=[1 0 5 4; 2 0 5 4; 3 4 6 2]; and I am using the below code ( see my previews question Plot the numbers of a matrix as points (dots) in a plot) while any(A(:) > 0) [r,c] = find(A>0); X= randn; Y= randn; a=c+X b=r+Y A = A-1; end
it returns for a and b a =
1.4471
1.4471
1.4471
2.4471
3.4471
3.4471
3.4471
4.4471
4.4471
4.4471
b =
1.5364
2.5364
3.5364
3.5364
1.5364
2.5364
3.5364
1.5364
2.5364
3.5364
a =
0.6514
0.6514
1.6514
2.6514
2.6514
2.6514
3.6514
3.6514
3.6514
b =
3.1841
4.1841
4.1841
2.1841
3.1841
4.1841
2.1841
3.1841
4.1841
a =
1.2058
2.2058
3.2058
3.2058
3.2058
4.2058
4.2058
b =
3.1324
3.1324
1.1324
2.1324
3.1324
1.1324
2.1324
a =
1.4771
2.4771
2.4771
2.4771
3.4771
3.4771
b =
3.9398
1.9398
2.9398
3.9398
1.9398
2.9398
a =
1.6379
1.6379
1.6379
b =
0.2081
1.2081
2.2081
a =
3.6630
b =
3.5855
how can I have all the numbers of a and b in one vector respectively ?
Stephen23 on 10 Jun 2015

Stephen23 on 10 Jun 2015
Edited: Stephen23 on 10 Jun 2015
Although it is slightly different in operation, you could try this:
A = [1 0 5 4; 2 0 5 4; 3 4 6 2];
N = sum(A(:));
X = randn(N,1)/12;
Y = randn(N,1)/12;
[R,C] = find(A>0);
B = A(A>0);
X = X + cell2mat(arrayfun(@(z,m)repmat(z,m,1),C,B,'UniformOutput',false));
Y = Y + cell2mat(arrayfun(@(z,m)repmat(z,m,1),R,B,'UniformOutput',false));
scatter(X,Y,[],randperm(N),'filled')
axis(gca,'ij')
colormap('winter')
which generates this figure:
The main differences from your code is that it generates all values at once (in the vectors X and Y) rather than within a loop, and it also uses a different random position for each point (rather than applying one random value to all points at each step of the while-loop). The code assumes that all values of A are positive integers or zero.
Stephen23 on 10 Jun 2015
There is nothing wrong with being a beginner! Everyone here on this forum was once a beginner... it just takes time and lots of practice to learn a tool like MATLAB:
• Read lots of examples of good MATLAB code
• Learn to use the documentation.
• Use this forum to learn some good techniques.
Good luck and have fun with MATLAB!