Count the number of times a value repeats between certain rows in a matrix.

Hi all,....if i had a Matrix Ex...A(2,5,15,65,102

2,65,1,105,55

65,104,15,19,5).....so on.

how to find the total number of times a value repeats between Row1 and Row2....Ans 2,65

then Row2 and Row3....Ans 65.

then Row3 and 4......and so on..

Also inputting which rows i want to check.....maybe between row1 and row4 for example....then row2 and row5....and so on,would be very helpful

Thank you.

[Matt J]

Why is ans 65 in rows 1 and 2? The number of common elements between the two rows is 2.

[ray d]

ok....im looking to find the common elements between rows 1 and 2...which would be 2..(value 2 and 65).yes..

then row2 and 3.....answer would be 1...(value65).

that make better sense.....than the actual values.

Answer 1

[Matt J]

A=[2,5,15,65,102;
   2,65,1,105,55;
   65,104,15,19,5];



skip=1;

A1=A(1:end-skip,:); A2=A(skip+1:end,:);

M=size(A,2);

result=0;
for i=0:M-1

    result=result+sum(A1==circshift(A2,[0,i]),2);
    
end
result

result = 2×1

2 1

[ray d]

Nailed it!.......Thank you Matt....does the job nicely.....thanks again

[Matt J]

Note that if you have repetitions within a row,e.g.

A(1,:)=[2, 2 5,15,65,102]

you may get unexpected results.

[ray d]

Ok.....understand......wont be any repetitions.....thanks again

Answer 2

[David Hill]

A=[2,5,15,65,102;2,65,1,105,55;65,104,15,19,5];
i=A(1,ismember(A(1,:),A(2,:)));

[ray d]

Hi Dave....thank you for the answer...yes,thats what im looking for...but ...to count down thro the rows.....count same elements in row1 and 2.....then row2 and 3....then row3 and 4....and so on.....done with a loop??....n and n+1 for the rows??....im unsure.

[ray d]

Thank you for the input Dave......solved