How to compare and merge matrices with same numbers?

I have a question about a code. I have two matrices, A and B. I would like to compare these two matrices based on the values of the columns 2 and 3. for example:

A=[1 2 3 4

9 6 7 8

10 5 4 7]

and

B= [8 2 3 4

11 6 7 8

5 5 6 7]

It is noticed that rows have same values of 2nd and 3rd column.

After the comparison of these two matrices I would like to create a new matrix C which would include keep the same rows of A and Bmatrix and

and finally to merge them (I want to keep the rows of table A that have the same values as columns 2 and 3 of table B. Finally, I want to build a matrix which will have the rows of table A and the rows of B that have the same value in the 2nd and 3rd columns)

I mean C= [ 1 2 3 4

9 6 7 8

10 5 4 7

5 5 6 7 ]

I have tried

clc
clear

T1=readmatrix('file1.txt');
T2=readmatrix('file2.txt');
A=T1(:,2:3); 

B=T2(:,2:3); 

C=[A;B];

C(:,end) = [];
[~,~,jj] = unique(C,'rows','stable');
C([false; diff(jj) == 0],:) = [];
writematrix(C,'output.txt','delimiter','\t');

could you please help me?

Answer 1

[Jan]

A =[ 1 2 3 4; ...
     9 6 7 8; ... 
    10 5 4 7];
B = [ 8 2 3 4; ...
     11 6 7 8; ... 
      5 5 6 7];

m = ismember(B(:, 2:3), A(:, 2:3), 'rows');
C = cat(1, A, B(~m, :))

C = 4×4

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

[Ivan Mich]

Ok thank you. One more question. If I the last column of both matrices A and B include alphanumeric (for example

A =[ 1 2 3 4 USA; ...
    9 6 7 8 LA; ... 
    10 5 4 7 TEX];
B = [ 8 2 3 4 USA; ...
    11 6 7  LA; ... 
    5 5 6 7 MA];

How could I get in the last column of matrix C the last column of the corresponding matrix.

for example how could I get a matrix like?

C = 
1     2     3     4 USA
9     6     7     8 LA
10     5     4     7 TEX
5     5     6     7 MA

Could you please help me?

[Jan]

@Ivan Mich: The elements of arrays must have the same type in Matlab. Only cell arrays can contain elements of different types and sizes. This means, that you cannot create this A and B an in consequence cannot create C.

So reformulate the question using some valid input arguments. Then the needed code should be exactly, what I have posted already.

[Peter Perkins]

"Only cell arrays can contain elements of different types and sizes." Jan, for different types at least, that's not been true for many years.

>> t1 = table([1;9;10],[2;6;5],[3;7;4],[4;8;7],["USA";"LA";"TEX"])
t1 =
  3×5 table
    Var1    Var2    Var3    Var4    Var5 
    ____    ____    ____    ____    _____
      1      2       3       4      "USA"
      9      6       7       8      "LA" 
     10      5       4       7      "TEX"
>> t2 = table([8;11;5],[2;6;5],[3;7;6],[4;7;7],["USA";"LA";"MA"])
t2 =
  3×5 table
    Var1    Var2    Var3    Var4    Var5 
    ____    ____    ____    ____    _____
      8      2       3       4      "USA"
     11      6       7       7      "LA" 
      5      5       6       7      "MA" 
>> tf = ismember(t1(:,2:3),t2(:,2:3),"rows")
tf =
  3×1 logical array
   1
   1
   0
>> [t1; t2(~tf,:)]
ans =
  4×5 table
    Var1    Var2    Var3    Var4    Var5 
    ____    ____    ____    ____    _____
      1      2       3       4      "USA"
      9      6       7       8      "LA" 
     10      5       4       7      "TEX"
      5      5       6       7      "MA" 

[Jan]

@Peter Perkins: Okay, I did not consider a table as an elementary array. They are more similar to a struct, such that the columns are equivalent to the fields and can have different types.

[Peter Perkins]

Fair enough. I will say, though, that while "like a scalar struct containing vectors" is one way to think about tables, it's equally valid to think about them as "like a double, or string, or [your favorite type of data] array with much of the same array functionality built around a rectangular topology, but allowing multiple types".

Tables for thie use in this post are certainly better than cell arrays.

[Jan]

@Peter Perkins: My point was, that:

A =[ 1 2 3 4 USA; ...
    9 6 7 8 LA; ... 
    10 5 4 7 TEX];

is not a valid Matlab matrix, especially if it was an expanded:

C=  [ 1 2 3 4; ...
      9 6 7 8; ... 
     10 5 4 7; ...
      5 5 6 7];

If the OP specifies if tables or cell arrays are meant, the answer can be adjusted.

[Ivan Mich]

Is there a way to show where each row came from in my final table (Table C)?

eg the first row is from file 1 (table A), the second row from file 2 (Table B) etc.?

[Peter Perkins]

Sure. You know that the first height(t1) rows in the result came from t1, and the last sum(~tf) rows came from t2. Add a variable to the result that's something like [ones(height(t1),1); 2*ones(sum(~tf),1)].