MATLAB: Pre-allocating structures

Question

Hello everyone,

I'm trying to pre-allocate memory for a structure defined as follows:

% S   : Structure containing geometrical description of polygons.
%         S(i) contains all information relative to the i-th shape
%         S(i).P(j) gives access to the geometrical description of the j-th
%         element of the i-th shape. 
%               XData : S(i).P(j).x    : Vector
%               YData : S(i).P(j).y    : Vector
%               Hole  : S(i).P(j).hole : Binary value

I'd like to pre-allocate before the following loop:

for i=1:ne
   for j=1:2
       S(i).P(j).x = v_proj(f(i,j),1);
       S(i).P(j).y = v_proj(f(i,j),2);
       S(i).P(j).hole = 0;
   end
end

I'd like to have a number of shapes ne.

But I don't really know how to do that. Any help would be more than welcome.

Thank you very much,

% Romain

Answer 1

One way to preallocate:

P(1:2) = struct('x',zeros(10,1),'y',zeros(1,2),'hole',false);
ne = 10;
[S(1:ne).P] = deal(P);