I want to initialize a very large character array with the same character string

The array is so large it takes forever for MATLAB to do it with a simple loop, e.g.;

for i = 1:N A(i) = 'String' end

I know this can be done numerically using ones (* the desired value) in a single line of code. Can it be done with a character string in a way that speeds up the process?

Thanks, David

[Jan]

The shown loop cannot work, because you try to assign a CHAR vector to a scalar element. What is the wanted result? Do you want a cell string {'String', 'String', ...} or a CHAR vetor 'StringString...'?

Answer 1

[Iain]

 char_array = char(ones(N,1) * 'String');

 cell_version = repmat({'String'},N,1);

Answer 2

[Ahmed]

Have you tried 'repmat'?

N = 100000;
A = repmat('String',N,1);

If you must use a for-loop, you should pre-allocate the array. If uninitialized, the growing of the array will consume a lot of time. Here, an example of preallocation and filling with loop.

N = 100000;  
A = repmat(char(0),N,6);
for i = 1:N, A(i,:) = 'String'; end

[Jan]

It is much faster to operate on the columns and assign scalars:

N = 100000;  
A = repmat(char(0),N,6);
S = 'String';
for k = 1:6
  A(:, k) = S(k);
end