# Scanning a column in matrix with repeated values

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Sunny am 19 Dez. 2018
Kommentiert: Sunny am 20 Dez. 2018
There are four coulmns (Subject, Number, ID, ANS) in a table named 'List'. I initialized a structure with each cell having zero matrices for unique value in subject list based on below code. Once this is done I want to scan the column Subject(which has repeated values) and place the ANS value of each row in the Zero matrix of that subject number at 'IDxNumber' (index). This repeates for every subject value found in the Subject column which is 10 next.
List table
Subject Number ID ANS
9 1 10 -1
9 2 10 1
9 3 10 -1
10 1 5 1
10 2 6 -1
c = 1;
for b = 1:max(List.Subject)
for a = 1:length(List.Subject)
if List.Subject(a) == b
count_id = sum(List.Subject(:) == b);
Subject_Assist{c} = zeros(101,count_id);
c = c+1;
end
end
end
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Sunny am 19 Dez. 2018
Its a table.

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### Akzeptierte Antwort

the cyclist am 19 Dez. 2018
Bearbeitet: the cyclist am 19 Dez. 2018
This code does the initialization. I'm still trying to figure out what you mean about filling it in.
[Edited afterward to fill in.]
% The original data
Subject = [9;9;9;10;10];
Number = [1;2;3;1;2];
ID = [10;10;10;5;6];
ANS = [-1;1;-1;1;-1];
% The original table
List = table(Subject,Number,ID,ANS);
% Find the unique subjects, and their corresponding rows
[uniqueSubject,~,indexFromUniqueBackToAll] = unique(List.Subject);
numberUniqueSubjects = numel(uniqueSubject);
% Create a cell array with one element per subject
output = cell(numberUniqueSubjects,1);
% For each subject ...
for ns = 1:numberUniqueSubjects
% Index that subject;s rows
indexThisSubjectsRows = find(indexFromUniqueBackToAll==ns);
numberRowsThisSubject = numel(indexThisSubjectsRows);
% initialize a matrix of zeros of apprpriate size
output{ns} = zeros(101,numberRowsThisSubject);
% Fill in ANS at the indicated rows
for ni = 1:numberRowsThisSubject
output{ns}(List.ID(indexThisSubjectsRows(ni)),List.Number(indexThisSubjectsRows(ni))) = List.ANS(indexThisSubjectsRows(ni));
end
end
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Sunny am 20 Dez. 2018
I figured out the issue its due to NaN. Thanks

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