Partition a Big Matrix Into Pieces According to Values from A Vector

I have a big matrix (approx 2000x2000 size). Based on another boolean vector (which is 2000x1), i want to remove rows or columns from a copy of the original big matrix, wether the i-th element of the vector is equal to 0 or not. By using the following code:

if true
   A = rand(2000); % Generate Random Matrix
   b = zeros(2000,1); % Initialize Vector
   for l=1:size(b,1)
       c = rand(1);
       if c>0.5;
       b(l,1) = 1; % Just Putting Random 1's in the Vector
   end
   row_id = find(Boun); % Create a Vector Containing the Indices of Rows/Columns to Eliminate
   A_copy = A; % Copy of the Original Matrix
   counter = 0; % Create a Counter      
   for m=1:size(row_id,1);
   A_copy(row_id(m)-counter,:) = []; % Eliminate row
   A_copy(:,row_id(m)-counter,:) = []; % Eliminate column
   counter = counter +1
   end     
end

The efficiency of the method is very poor. I know that messing around with matrices dimensions is not a good idea. Any suggestions?

Thanks in advance.

Answer 1

[the cyclist]

Instead of the for loop, you can do

A_copy(row_id,:) = []; % Eliminate rows
A_copy(:,row_id) = []; % Eliminate columns

[Alessandro]

Thanks, this makes me save a lot of time!