Sorting cell for only dublicate values

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Magnus Rasmussen
Magnus Rasmussen on 25 Oct 2021
Edited: dpb on 26 Oct 2021
Hi i have a cell containing strings which are only 3 characters. I wish to sort this cell so only values that appear twice or more will remain. I thought about using a logical array, and using fun2cell, but i cant seem to get it quite right.
  3 Comments
Magnus Rasmussen
Magnus Rasmussen on 25 Oct 2021
Of course. I will try and give as much information as i can
BSW01_Rawtable is from the readtable function where import an excell sheet. "b" is one column from the excell sheet.
Here you see the content of b. I wish to sort it so every value appears twice or more. If there is less than 1 entry of value for example A05, i wish to have it sorted out of the list.
Hope this clarify things. Thanks for your quick replies. I know it would probably be faster to just sort it manually in the excell sheet, but i got more things of the same task and i value the learning experience. Apologies for my bad matlab language.

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Accepted Answer

dpb
dpb on 25 Oct 2021
Edited: dpb on 26 Oct 2021
Alternate approach to Jan's using features of categorical arrays (which the IDs logically are)
% some dummy data of the same type as the example -- convert to categorical
>> CID=categorical(sort(cellstr(strcat(char('A'+randi([0 2],10,1)),num2str(randi(5,10,1),'%02d')))));
>> CID
CID =
10×1 categorical array
A02
A03
A04
B02
B02
B02
C02
C02
C04
C04
>>
% The engine
c=categories(CID); % a list of the categories (unique list of IDs)
isG1=(countcats(CID)>1); % logical vector of those with >1 occurrences
ID=CID(ismember(CID,c(isG1))); % select those out of the total list
The above yields
>> ID
ID =
7×1 categorical array
B02
B02
B02
C02
C02
C04
C04
>>
which can be seen by inspection to be the duplicates in the original list.
  1 Comment
Magnus Rasmussen
Magnus Rasmussen on 26 Oct 2021
Yes this is perfect. Thank you very much.

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More Answers (1)

Jan
Jan on 25 Oct 2021
Is the input really a cell containging strings? Or a cell string? Ort a string array?
% Test data with a cell string:
data = sprintfc('%03d', randi([0, 100], 1, 100));
data = sort(data(isMultiple(data)))
function T = isMultiple(A)
[S, idx] = sort(A(:).');
if iscellstr(A)
m = [false, strcmp(S(1:nA - 1), S(2:nA))];
elseif isa(A, 'string')
m = [false, (S(1:nA - 1) == S(2:nA))];
else
error(['Jan:', mfilename, ':BadInputType'], ...
'Input type is not handled: %s', class(A));
end
ini = strfind(m, [false, true]);
m(ini) = true; % Mark 1st occurence in addition
T(idx) = m; % Restore original order
end

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