Replace elements between two matrices

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Ismaeel 2016-12-6

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编辑： Ismaeel 2016-12-7

I have two matrices A and B:

A= [8 1;
   16 2];
B= [8 10;
   16  5]

I want to replace any element in B that exist in the 1st column of A, by its corresponding value in the second column of A. The result should be:

C=[1 10; 
   2  5];

Thanks for help

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Answer 1

Image Analyst 2016-12-7

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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)

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Ismaeel 2016-12-7

That is what I was looking for, thank you so much.

Ismaeel 2016-12-7

编辑：Ismaeel 2016-12-7

Image Analyst, sorry but how about if size(A)~=size(B)? I have a case in this pattern.

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Answer 2

Chaya N 2016-12-7

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Try the setxor function. You may need to tweak the directionality of the inputs a bit, so use something like

C = setxor(A',B','rows')'

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Image Analyst 2016-12-7

在 MATLAB Online 中打开

Ismael, this code:

A= [8 1;
   16 2]
B= [8 10;
   16  5]
C = setxor(A',B','rows')'

gives

which is the C you originally asked for. Now you're giving a different desired value for C. Which is it?

Ismaeel 2016-12-7

编辑：Ismaeel 2016-12-7

That is true for the case when the first column in A and B are the same. How about if some elements of the 1st column of B are not similar to the elements in the 1st column of A. If, for instance, the element (1,1) in B which is =8 is any number except 8, I don't want to keep different elements and replace similars with their corresponding second column in A.

Simply,

if B(i,1)==A(i,1)

replace B(i,1) with A(i,2)

otherwise don't change

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