MATLAB: How to delete a row if it doesn’t follow a pattern

delete rowpattern

Hi, I have… a = [ 2 5 1; 3 6 2; 3 4 1; 9 4 2; 8 3 1; 3 2 2; 9 5 2; 4 8 1]

 Notice how the last column follows a pattern of 1, 2,1,2..and so on.
 The 7th row however has a 2 in the last column just like the 6th row before...thus does not follow the pattern. 
 How would I delete the 7th row and any other row if it does not follow the 1,2,1,2 pattern of the last column?
 Thanks.

Best Answer

Try out this code :

    p=size(m,1);%m is your matrix
for i=1:p
    if mod(i,2)==1 &&  m(i,size(m,2))~=mod(i,2)
        m(i,:)=[];
        p=p-1;
    elseif mod(i,2)==0 &&  m(i,size(m,2))~=(mod(i,2)+2)
        m(i,:)=[];
        p=p-1;
    end
end

Related Solutions

MATLAB: Delete row not following pattern

Assuming the pattern in the next-to-last column must be 1-2-1-2-...etc exactly

[m,n] = size(a);
n1 = n - 1;
expected = 1; % initialize expected value in 1st row

x = false(m,1); % initialize the deletion flag array
keep = 0; % initialize row to keep when marking for deletion
v = 0.5; % discriminator value for deciding which line to delete
for k=1:m
    if( a(k,n1) ~= expected ) % if not as expected, mark one line for deletion
        if( keep == 0 || abs(a(k,n)-v) > abs(a(keep,n)-v) )
            x(k) = true; % mark current line for deletion
        else
            x(keep) = true; % mark previous line for deletion
            keep = k;
        end
    else
        expected = 3 - expected; % if as expected, update expected
        keep = k;
    end
end
a(x,:) = []; % delete the unexpected pattern rows

If the first line can start with a 2 rather than a 1, change this line:

expected = a(1,n1); % initialize expected value in 1st row

MATLAB: Delete duplicated row in a matrix

   I = ~ismember(a(:,1:2),b(:,1:2),'rows');
   a = a(I,:)

Best Answer

Related Solutions

MATLAB: Delete row not following pattern

MATLAB: Delete duplicated row in a matrix

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