Create a matrix out of single values if a for loop?

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gamer 2021-6-17

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https://ww2.mathworks.cn/matlabcentral/answers/858405-create-a-matrix-out-of-single-values-if-a-for-loop

评论： gamer 2021-6-17

采纳的回答： KSSV

在 MATLAB Online 中打开

Hello,

is it possible to create a 1xF matrix in a for loop out of single values?

n = 2;
r = 0.5;
a = 10;
b = 5;
p = [r + (a-2*r)*rand(n,1),r + (b-2*r)*rand(n,1 )];
for i = 1:n
    for j = i:n
        if i == j
            continue
        end
        H = (norm(p(i,:)-p(j,:))<=2*r)
    end
end

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SungJun Cho 2021-6-17

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You should preallocate H as a matrix and save each values into your matrix. For example,

% ...
H = zeros(n,n);
for i = 1:n
    for j = i:n
        % ...
        H(i,j) = (norm(p(i,:)-p(j,:))<=2*r)
    end
end

gamer 2021-6-17

在 MATLAB Online 中打开

I tried it like that but it just gives me again 3 matrices back instead of one

r = 0.5; a = 0; b = 5; n = 3
p=[r + (a-2*r)*rand(n,1),r + (b-2*r)*rand(n,1)];
H = zeros(1,((n-1)*n)/2 )
for i = 1:n 
for j = i:n 
 if i == j
     continue
 end
H(1,((n-1)*n)/2) = (norm(p(i,:)-p(j,:)))
end 
end

I want the norm of (p(1,:) - p(2,:), p(1,:) - p(3,:) and p(2,:) - p(3,:) in one matrix. This is just an example for n = 3.

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采纳的回答

KSSV 2021-6-17

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/858405-create-a-matrix-out-of-single-values-if-a-for-loop#answer_726805

在 MATLAB Online 中打开

r = 0.5; a = 0; b = 5; 
n = 3 ; 
p=[r + (a-2*r)*rand(n,1),r + (b-2*r)*rand(n,1)];
H = zeros(1,[]) ;
count = 0 ; 
for i = 1:n 
for j = i:n 
 if i == j
     continue
 end
 count = count+1 ; 
H(1,count) = (norm(p(i,:)-p(j,:)))
end 
end