MATLAB: Eliminating Multiple rows using ‘if’ conditional

for loopif statementmatrices

Is it possible to eliminate multipe rows of a matrix using IF conditional?
 A=[1  1875  507
1  1880  508 %repeat 



1  1885  508 %repeat (eliminate this row)


1  1890  508 %repeat 
1  1895  512
2  1720  501
2  1730  502 %repeat 
2  1740  502 %repeat (eliminate this row)
2  1750  502 %repeat (eliminate this row)
2  1760  502 %repeat 
2  1770  505]
 Here, A(3,:), A(8:9,:) are to be eliminated. 
So that the the result would look like:
 B=[1  1875  507
1  1880  508
1  1890  508
1  1895  512
2  1720  501
2  1730  502
2  1760  502
2  1770  505]
How can such elimination be done using IF loop for a matrix bigger than this where it is very inefficient to do so for every unique value in Column1?
Thank you

Best Answer

Given your very special requirement for first and last rows, you might be able to use the unique() command. Does this work for you?
[~,indexToFirst] = unique(A(:,[1 3]),'rows','first');
[~,indexToLast]  = unique(A(:,[1 3]),'rows','last');
indexToFirstAndLastRows = union(indexToFirst,indexToLast);
A = A(indexToFirstAndLastRows,:)
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