how to deletes rows after a certain row

I got a 100*1 matrix and i sort them as descendibg order. After that i want to delete the worse half of the matrix to get a 50*1 matrix how could i get it?

Answer 1

[Star Strider]

Try this:

Data = randi(99, 100, 1);                               % Create Data
Sorted_Data = sort(Data, 'descend');                    % Sort Descending
Keep_Data = Sorted_Data(1:50);                          % Data To Be Kept

[Berkay Can]

Actually i have to detail my problem cause your answer worked but not as i want. İ got a 25*3 matrix right now and i sort them as descending order based on the third column. right now i want to delete the worst %50. i tried it as:

half = size(island1,1)/2; %to get the hal of the number of rows

island1_best = island1(1:round(half));

but i just got the first column of my matrix as a row :/

thank you anyway :D

[Walter Roberson]

island1_best = island1(1:round(end/2),:);

assuming that it was sorted on the first column

[Berkay Can]

Thank you so much it worked :D Appreciated you.