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matlabmatrixconditional-statements
user3244095
user3244095

Reputation: 13

removing rows from matrix based on specific conditions

I have a matrix 65536x8 with all possible combinations of values - 45 90 135 180 (in 8 columns).

I need to remove all the rows that do not contain all four values (each row cannot be missing any of these values).

This is what I've tried (not working):

>> orient(orient(numel(orient(:,1))) == 45 && 90 && 135 && 180,:)

ans =

   Empty matrix: 0-by-8

Is there some efficient way to do this in MATLAB?

Upvotes: 1

Views: 532

Answers (1)

Dan
Dan

Reputation: 45752

This should give you an idea of how to go about it:

A = [1 1 1
     1 1 2
     1 1 3
     1 2 1
     1 2 2
     1 2 3
     1 3 1
     1 3 2 
     1 3 3
     2 1 1
     2 1 2
     2 1 3];


A(any((A == 1)') & any((A == 2)') & any((A == 3)'),:)

ans =

   1   2   3
   1   3   2
   2   1   3

Or generically using a loop (with only 4 number this should be pretty fast):

rows = true(size(A,1),1);              %// Initialization
U = unique(A);                         %// List of numbers
for n = 1:size(U,1)
    rows = rows & any((A == U(n))')';
end
A(rows,:)

Upvotes: 1

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