Eliminate rows from an array

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José Santos Pérez Leal
评论： José Santos Pérez Leal 2021-6-12
Hi everyone
How can I cut a 31450X1 array in order to obtain the same array with a dimension of 15725X1, eliminating the second half of rows from the original array? The array is a variable I'm working with, but I can't solve that problem. I tried it creating the next code:
LEN=length(data3);
for x=1:LEN
if x>(LEN/2)
ROW=LEN;
data3(ROW,:)=[];
end
end
Where data3 is the 31450X1 array, but the matrix index is out of range for deletion

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采纳的回答

Image Analyst
Image Analyst 2021-6-12
To eliminate the "second half of rows" (like you asked) from your column vector, do this:
midRow = ceil(length(data3) / 2);
data3 = data3(midRow : end);
To eliminate every other row, do this:
evenRows = data3(2:2:end); % Extract even numbered rows only.
oddRows = data3(1:2:end); % Extract odd numbered rows only.
  1 个评论
José Santos Pérez Leal
José Santos Pérez Leal 2021-6-12
Thank you very much!!! I will analize it in order to understand your method, thank you!!

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更多回答（1 个）

Mouhamed Niasse
Mouhamed Niasse 2021-6-12
Hello, this is what you tried to achieve:
data3(1+length(data3)/2:length(data3),:)=[];
Try to run below example. Hope it helps you understand.
data3=ones(31450,1); % data3 initialized as row vector of size 31450x1
size(data3)
data3(1+length(data3)/2:length(data3),:)=[]; % Eliminate second half of rows
size(data3)
  1 个评论
José Santos Pérez Leal
José Santos Pérez Leal 2021-6-12
Thank you very much, Mouhamed!!! I'm going to analize your method in order to understand it, thanks!!

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