Delete specific rows on a large matrix?

Hello everyone,

I need some help, on a problem which looked pretty basic at the beginning. I have a very big matrix with 10947479 rows and 3 columns. But I don't need the values above 200 and it should remove the whole row. I tried like below:

 idx = V1(:,2) >= 200;
 V1(idx,:) = [];

Unfortunatly, the result is very bad. In the matrix are zeros now, while in the original matrix are none zeros at all. If I run the code like this:

V1(idx(1:10000),:) = [];

it works as supposed. I don't no why :( Does anyone know how I can solve my problem?

Answer 1

[Abdulrahman Abdulaziz S Aljurbua]

Hi ..

Did you try:

V1(201:end,:) = 0

This is supposed to make any row below the 200th enrty = 0.

or

V2 = V1(1:200,:) ;

This will store the value of the first 200 rows ov V1 in V2.