# How can I delete row based on the value of row (i) and row (i+1)

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Gadelhag M Omar Mohmed on 25 Oct 2018
Hi I am new to matlab, I am working with 1000*10 matrix. I want to delete the all row if the value in row (i) column 10 is the same as the value in row (i+1) column 10, and keep the row if the value in row (i) column 10 is not equal to the value in row (i+1) column 10. For example: my data file is X. and my code is, but it does not work with me :
for i=1:length (X)
if (X(i,10)~=X(i+1,10)
y(j,1:10)= X(i,1:10);
j=j+1;
else
y(j,1:10)=[];
end
if true
% code
end
end

James Tursa on 25 Oct 2018
Edited: James Tursa on 25 Oct 2018
I think this is what you are asking for (i.e., delete all rows that have equal neighbors in column 10):
n = 10; % the column to use for the comparison
d = diff(X(:,n)); % the 0's in d indicate where neighbors are equal to each other
d = [d;1] .* [1;d]; % vector that has 0's for all rows that are equal to neighbors
X(~d,:) = []; % delete the rows that have equal neighbors using logical indexing
Gadelhag M Omar Mohmed on 29 Oct 2018

madhan ravi on 25 Oct 2018
for i=1:length (X)
if (X(i,10)~=X(i+1,10)
y(i,:)= X(i,:);
else
y(i,:)=[];
end
end
madhan ravi on 25 Oct 2018
Edited: madhan ravi on 26 Oct 2018
Note: I didn’t per-allocate the array because the resultant matrix is unknown since you didn’t provide data but if you know the resultant matrix you can simply do
y =zeros(1000,10)
Gadelhag M Omar Mohmed on 29 Oct 2018