Create new column for data after each iteration of a for loop

Hello, i'm trying to understand how to create a column for data after each iteration of a for loop. I need to run the loop 50 times, and recover the data inside of one matrix. The vector t should change with each iteration of the loop, and this is what I want to record into S matrix as columns... but I cant seem to get it.

if true
% clear all
% lambda, firing rate
lambda = 10;
%total time of simulation 5 seconds
totalTime = 5000; % milliseconds
N = 50; % # trials
spikeTimes = [];
spikeTrain = []; 
% Loop
for i = 1:N
  for T = 1 : totalTime*1.2
      if lambda / 1000 >= -log(rand());
         spikeTimes(end + 1) = T;
      end
      isi = diff(spikeTimes);
      t = cumsum(isi)/1000;
  end
  S = t(:);  % <-------- ????
end
end

Any help would be appreciated!!

Answer 1

[Benjamin Avants]

As the code appears in your question, you are overwriting S in every loop.

Assuming you don't have a length mismatch as Sara pointed out, that line should read like this:

S(:,i) = t;

or this

S(:,i) = t';

depending on whether t is a column or row vector.

You probably will have a length mismatch since number of spikes and spike times are pseudo random, so you will either need to follow Sara's advice to use a cell array or preallocate an array of NaN's at some number larger than the number of spikes you expect x 50. Saving t into S would then look like this:

S = nan(10000,50);
% loop
% calculations
S(1:numel(t),i) = t;
% end loop

Answer 2

[Sara]

It seems that the vector t could be of different size at each iteration, depending on the if condition. If that's the case, consider using:

S = cell(N,1)

before the for loop and

S{i} = t;

to store t in a cell array.