MATLAB: Finding duplicate number and adjacent row value

duplicate

Suppose I have a matrix of values
v = [1 4; 1 5; 2 4; 2 4; 2 5; 2 5; 3 4; 3 7]
in column one the numbers are consecutive but with repetition, how can I find only the first numbers and corresponidng number in the other column, put them in a new matrix (v')? The new matrix should be like this from my example:
v'= [1 4; 2 4; 3 4]
I hope I am clear enough
Cheers
Sobhan

Best Answer

v = [1 4; 1 5; 2 4; 2 4; 2 5; 2 5; 3 4; 3 7]
idx=diff(v(:,1))
v1=[];
if idx(1)==0
  v1=[v1;v(1,:)]
end      
for k=2:length(idx)
  if idx(k)==0 & idx(k-1)~=0
    v1=[v1; v(k,:)]
  end
end
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