MATLAB: Replacing elements of a Matrix meeting conditional

replace conditional

Hi, I have two matrixes and wish to replace the first column of matrix A, with elements of the fourth column of matrix B, but just in the case the elements of the first columns of A and B are equal.

I tried the following, but its probably not correct. Can someone help me out?

for j=1:size(A,1)

    if A(j,1)==B(:,1);
        A(j,1)=B(:,4);
    end
end

Best Answer

A=rand(14,5);A(:,1)=1:14;
B=rand(5,4);B(:,1)=10:-2:2;B(:,4)=10*B(:,1);
[Dummy,IndexA,IndexB]=intersect(A(:,1),B(:,1));
A(IndexA,1)=B(IndexB,4)

Related Solutions

MATLAB: How to check if two elements are in a row of a matrix

Here is one clumsy way:

A=[1 2;
   4 5;
   6 9];
B=[1 3 5 6;
   1 2 4 7;
   5 6 4 8;
   1 2 3 4];
rowCountA = size(A,1);
rowCountB = size(B,1);
this_row_of_A_is_in_B = false(rowCountA,1);
for nb = 1:rowCountB
    this_row_of_A_is_in_B = this_row_of_A_is_in_B | all(ismember(A,B(nb,:)),2);
end
rows_of_A_that_are_not_in_B = A(not(this_row_of_A_is_in_B),:)

MATLAB: Replace elements between two matrices

Try this:

A= [8 1;
   16 2]
B= [8 10;
   16  5]
% If A & B are integers
rowsToReplace = A(:, 1) == B(:, 1)
C = B; % Initialize C to B.
% Now, replace the rows that need replacing:
C(rowsToReplace, 1) = A(rowsToReplace, 2)

Best Answer

Related Solutions

MATLAB: How to check if two elements are in a row of a matrix

MATLAB: Replace elements between two matrices

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