Remove zeros from a vector from a specific position

Hello, I have the following vector as example:
X=[0, 0; 0.02, 2.3;0.04, 0.4; 0, 0; 0.06, 2.5; 0.08, 3.6; 0, 0; 0.10, 2.5]
I want to remove the zeros and I only want to keep the zeros at the beginning and obtain the following matrix:
X=[0, 0; 0.02, 2.3;0.04, 0.4; 0.06, 2.5; 0.08, 3.6; 0.10, 2.5]
I know this option
X( all(~X,2), : ) = [];
which eliminates all the zeros and then I can add the zeros again at the beggining using
X=vertcat([0 0],X);
but there must be a direct way to do it. I would appreciate the help.

2 commentaires

Will there always be at least one row of zeros at the beginning?
If so, will there always be exactly one row of zeros at the beginning?
Yes, there will be always zeros at the beginning.

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 Réponse acceptée

remove = all(~X,2);
remove(1) = false;
X(remove,:) = [];

6 commentaires

Bruno Luong
Bruno Luong le 18 Août 2023
Modifié(e) : Bruno Luong le 18 Août 2023
One liner
X([false;all(~X(2:end,:),2)],:)=[];
I think something is missing. Thank you.
Fixed
THANK YOU VERY MUCH. :).
FYI, this solution will not work if there are multiple rows of leading zeros to keep. (That's why I asked if there was always exactly one row of leading zeros.) For example,
X = [0, 0;
0, 0;
2, 3;
5, 7;
0, 0];
X([false;all(~X(2:end,:),2)],:)=[]
X = 3×2
0 0 2 3 5 7

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