Groupcount function sort data in alphabetical order

12 views (last 30 days)
Dear MatLab users,
I have a cell array (attached) containing the IDs of my events. I used the groupcount function to see how many instances and how many events I had, and everything seemed to work fine. However, I just found out that the resulting variable containing the events sorted the data in alphabetical order. Thus, the counting also refers to the modified order, which is something I do not want. I managed to find the instances manually, but I also need the list in the original order. Is there a way to do using the groupcount function?
[ N , EVENTS ] = groupcounts(event_id); % EVENTS are in alphabetical order

Accepted Answer

Jan
Jan on 8 Jun 2022
Edited: Jan on 8 Jun 2022
% groupcounts sorts the input:
C = {'C', 'C', 'C', 'A', 'A', 'E', 'E', 'E', 'E', 'B'}.';
[N, EVENTS] = groupcounts(C)
N = 4×1
2 1 3 4
EVENTS = 4×1 cell array
{'A'} {'B'} {'C'} {'E'}
% 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)
N = 4×1
3 2 4 1
EVENTS = sEVENTS(q)
EVENTS = 4×1 cell array
{'C'} {'A'} {'E'} {'B'}
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
  4 Comments
Jan
Jan on 9 Jun 2022
There is no need for apologies. You are the only person who needs this function and I spend my time voluntarily to find solutions. Questions for clarifications are a standard part of solving problems.
I'm happy, if it is working now :-)

Sign in to comment.

More Answers (0)

Products


Release

R2020b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by