convert Vector into matrix ?

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Alex
Alex 2013-5-24
回答： Stephen23 2021-3-31
Hello, i need to convert a vector into matrix like this:
A = [1 2 3 4 5]
into
B=[1 2 3; 2 3 4; 3 4 5]
Any ideas ??

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Youssef Khmou
Youssef Khmou 2013-5-24
hi Alex
This is not conversion but you are adding new elements to the original vector :
If you have a vector of size Mx1 you can convert it to matrix using function reshape to get a matrix of size PxN such M=P*N.
r=randn(100,1);
y=reshape(r,10,10);
In your case , try :
A=1:5;
t=1;
r=3;
for n=1:3
B(n,:)=t:n+2;
t=t+1;
r=r+1;
end
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Mohammed Ghouse Mohiuddin
Mohammed Ghouse Mohiuddin 2021-3-31
For loops are too complex for me. I hate it. Nobody explains it to me in a logical way.
Image Analyst
Image Analyst 2021-3-31
@Mohammed Ghouse Mohiuddin, uncommented code (like Alex's) can be hard to understand. Everyone should use comments. If you can't figure it out, post a new question with the code you are trying to adapt and an explanation of what you really want to do (if you could adapt it). But read this link first.
TUTORIAL: How to ask a question (on Answers) and get a fast answer

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更多回答（6 个）

Image Analyst
Image Analyst 2013-5-24
I know it seem really really obvious, but if that is all we have to go on (i.e. no indication that it needs to be generalized in any way), then why not just do this:
B = [A(1:3);A(2:4);A(3:5)]
  1 个评论
Alex
Alex 2013-5-24
i am sorry, my mistake, A is big, it was just an example, exist other way to make this automatic ??

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Matt Kindig
Matt Kindig 2013-5-24
编辑：Matt Kindig 2013-5-24
It might not be very efficient, but I think it should work:
nc = 3; %number of columns in B
nc = nc-1;
c = 1:(length(A)-nc);
B = cell2mat(cellfun(@(n) A(n:(n+nc)), num2cell(c(:)), 'uni', false))
Youssef Khmou
Youssef Khmou 2013-5-25
hi, there are other alternatives , :
try :
N=32;
A=1:N;
A2=0:N-1;
A2=A2';
B=repmat(A,N,1);
for x=1:N
B(:,x)=B(:,x)+A2;
end
Youssef Khmou
Youssef Khmou 2013-5-25
hi,
here is the best solution without using loops :
N=32;
A=1:N;
B=repmat(A,N,1);
A2=(0:N-1)';
B2=repmat(A2,1,N);
C=B+B2;
anukriti dureha
anukriti dureha 2013-5-25
hi alex, you can do this:
i=1;
ind=0;
num=3;
while num <=5
ind=ind+1;
z{i}=A(ind:num);
num=num+1;
i=i+1;
end
z=cell2mat(x);b=vec2mat(z,3);
Stephen23
Stephen23 2021-3-31
Ran in:
A = [1,2,3,4,5];
B = hankel(A(1:3),A(3:5))
B = 3×3
1 2 3 2 3 4 3 4 5

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