Delete Lines if there are three e qual lines

Hi, i have this problem. I have a matrix A(m ; 8). I would have new Matrix B where are delete the Lines Whith this idea: if in matrix A There are three Numbers that are the same in Colomn 3 and 5, in the new Matrix delete this three Lines.

[madhan ravi]

give an example

[Giuseppe Antonacci]

for example i have this matrix A=[ 1 3 7 8 9 7 2 8 ; 9 0 3 5 2 1 4 9 ; 0 2 3 6 2 7 7 7 ; 3 2 3 5 2 2 5 7 ] .

in the second, third e forth lines there are the same number in the third e fiveth colomn for this reason i would delate all lines.

[madhan ravi]

What’s your desired output give an example

[Giuseppe Antonacci]

in this case A=[ 1 3 7 8 9 7 2 8 ; 9 0 3 5 2 1 4 9 ; 0 2 3 6 2 7 7 7 ; 3 2 3 5 2 2 5 7 ] B=[ 1 3 7 8 9 7 2 8 ] becouse in the other lines there are the same numbers in colomn three and five.

[KSSV]

It is not clear.....you need to explain more...

[jonas]

Let me guess

A =

     1     3     7     8     9     7     2     8
     9     0     3     5     2     1     4     9
     0     2     3     6     2     7     7     7
     3     2     3     5     2     2     5     7
                 ↑           ↑

Delete rows where three or more (consecutive???) columns share the same value? Clarify:

• consecutive duplicates only?
• limit the check to columns 3 & 5?
• exactly three duplicates or more than three?
• is the matrix always 4 rows?
• What if only column 3 has consecutive duplicates? Or only column 5?

To summarize: I don't think you have thought this through.

[Giuseppe Antonacci]

this matrix in an example. the matrix is (m;8). the first three point in correct.

Answer 1

[Stephen23]

This should get you started:

>> A = [1,3,7,8,9,7,2,8;9,0,3,5,2,1,4,9;0,2,3,6,2,7,7,7;3,2,3,5,2,2,5,7]
A =
   1   3   7   8   9   7   2   8
   9   0   3   5   2   1   4   9
   0   2   3   6   2   7   7   7
   3   2   3   5   2   2   5   7
>> B = [1,3,7,8,9,7,2,8] % expected output
B =
   1   3   7   8   9   7   2   8
>> X = diff(A(:,[3,5]),1,1)==0;
>> Y = X(1:end-1,:) & X(2:end,:);
>> Z = any(conv2(Y,[1;1;1])>0,2); % either column 3 OR 5
>> B = A(~Z,:)
B =
   1   3   7   8   9   7   2   8

If you want both columns to fit the condition:

Z = all(conv2(Y,[1;1;1])>0,2)

[madhan ravi]

Cool @ Stephen was struggling to figure it out thanks