Updating columns of a matrix

Consider the below code where we have population 'pop' having 20 individuals with a dimension of 5 and a subpopulation 'subpop' having 20 individuals with dimension 0f 3. I need to update first 3 columns of 'pop' with columns of 'subpop' for all rows. I know it can be done easily using a for loop, But I was wondering if it is possible to do it in a single line of code.

nPop    = 20;               % Population Size (Swarm Size)
varMin  = -5;               % Lower Bound of Variables
varMax  =  5;               % Upper Bound of Variables

%%Cooperative Co-evolution
D    = 5;                 % Dimension

empty_individual.Position = [];
pop = repmat(empty_individual, nPop, 1);

% Intializing Population
for i = 1:nPop
    pop(i).Position = (varMin + (varMax + varMax)*rand(D, 1))';
end

empty_individual.Position = [];
subpop = repmat(empty_individual, nPop, 1);

% Intializing sub Population
for i = 1:nPop
    subpop(i).Position = [1 1 1];
end

[Geoff Hayes]

Atones - given that pop is a struct, I don't think that you can replace the first three columns of your Position member in a single line of code. Using a for loop, in my opinion, makes it more clear what you are trying to do.