CODEWITHSUNDEEP
matlab
arWindsor
arWindsor

Reputation: 25

Matlab Matrix Manipulation

Is there a function in Matlab to assign matrix elements by blocks? For example: Matrix A =

 1     1     3     3     3     3     3     8     8    10
 1     1     3     3     3     3     3     8     8    10
 1     1     4     4     4     4     4     8     8    10
 1     1     4     4     4     4     4     8     8    10
 1     1     5     5     5     5     5     8     8    10
 2     2     5     5     5     5     5     9     9    10
 2     2     6     6     6     6     6     9     9    10
 2     2     6     6     6     6     6     9     9    10
 2     2     7     7     7     7     7     9     9    10
 2     2     7     7     7     7     7     9     9    10

Matrix B=

 1     1     1     1     1     1     1     1     1     1
 2     2     2     2     2     2     2     2     2     2
 3     3     3     3     3     3     3     3     3     3
 4     4     4     4     4     4     4     4     4     4
 5     5     5     5     5     5     5     5     5     5
 6     6     6     6     6     6     6     6     6     6
 7     7     7     7     7     7     7     7     7     7
 8     8     8     8     8     8     8     8     8     8
 9     9     9     9     9     9     9     9     9     9
10    10    10    10    10    10    10    10    10    10

The user wants to create another matrix C where elements in the matrix B that correspond to 1 in the matrix A go to the matrix C (in the same position), similarly elements in the matrix B that correspond to 2 in the matrix A go to the matrix C (in the same position) and so on.

Upvotes: 0

Views: 122

Answers (2)

p8me
p8me

Reputation: 1860

I t would very simple using Matlab operators (equality == in this case), and you don't need a function.

A == 1 would return all the indices of A (or B) that A is equal to 1 as a boolean matrix:

>> A == 1

ans =

     1     1     0     0     0     0     0     0     0     0
     1     1     0     0     0     0     0     0     0     0
     1     1     0     0     0     0     0     0     0     0
     1     1     0     0     0     0     0     0     0     0
     1     1     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0
     0     0     0     0     0     0     0     0     0     0

Then B(A == 1) will return all those true elements of the result above, in B (in a vector form):

>> B(A == 1)

ans =

     1
     2
     3
     4
     5
     1
     2
     3
     4
     5

So all you need is to equate C(A == n) to B(A == n):

C = zeros(size(B)); % Create a matrix C with proper size

for k = 1:10
   inds = A == k; % indices of A, B or C that correspond to A == k
   C(inds) = B(inds);
end

Upvotes: 2

am304
am304

Reputation: 13876

Not sure if I understand correctly, but are you trying to do something like that?

C = zeros(size(A));
for k=1:10
   C(B==k) = A(B==k); % or is it C(A==k) = B(A==k) ?
end

Upvotes: 0

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