% groupcounts sorts the input:
C = {'C', 'C', 'C', 'A', 'A', 'E', 'E', 'E', 'E', 'B'}.';
[N, EVENTS] = groupcounts(C)
% Let N and EVENTS have the same order as in C:
[~, iC] = unique(C); % [EDITED, bug fixed]
[~, q] = sort(iC);
[sN, sEVENTS] = groupcounts(C);
N = sN(q)
EVENTS = sEVENTS(q)
If the equal keys are guaranteed to be neighboring:
% Call this instead of GROUPCOUNTS to keep the order
function [n, b] = RunLength_CStr(x)
x = x(:);
nx = numel(x);
d = [true; ~strcmp(x(1:nx-1), x(2:nx))]; % TRUE if values change
b = x(d); % Elements without repetitions
n = diff(find([d.', true])); % Number of repetitions
end
