MATLAB: Analyzing the occurrences of strings within cells using loops

cell arraysloopsMATLAB

Good afternoon Matlab forums!
I've been working on a code to sort an array of data that includes both numbers and string values. Basically, within column 1 I have identification #'s, in column 2, I have strings, and in column 3 I have charges to be summed.
I am attempting to extract a histogram which shows the occurrences of the strings in column 2 based on particular conditions of the set. Basically, for each unique column 1 ID#(There are multiple occurences of the same here), I wish to check if Column 3 adds up to a particular threshold, in this case being 10,000. Here is a sample of my current code.
Q = cellfun(@str2num,SUB_ID,'UniformOutput',false);
D = cell2mat(Q);
concentated = [D C];
unique_ids = unique(concentated(:,1));
n_ids = length(unique_ids);
for i = 1:n_ids;
  A_id = concentated(concentated(:,1) == unique_ids(i),:);
  sum_id = sum(A_id(:,2));
  if sum_id >= 10000
    disp(unique_ids(i))
    disp(sum_id)
  end
end
The beginning of this code is me creating a 2 column matrix with the data in the array, excluding the previous "Column 2" data, as I can't seem to figure out how to make these loops work within in array as opposed to a matrix. Any help would be appreciated!!!
Thanks, J

Best Answer

I'm using a table here instead of cell arrays but the principle is the same. It's not clear if your SUB_IDs are always numerical or can also contain other symbols but in any case, you don't need to convert it to number. That's an unnecessary slow step. accumarray, ismember and some simple indexing will avoid any loop:
db = readtable('MatBookSample.xlsx'); %or read as cell array
[ids, ~, idlocations] = unique(db.SUB_ID);  %get all unique id values and their location
idcharge = accumarray(idlocations, db.CHRG_AMT); %calculate charge amount per id, in the same order as ids
idovers = find(idcharge > 10000);  %index of ids whose charge amount is above threshold
servovers = db.SERV_PROV(ismember(idlocations, idovers)); %corresponding serv_prov
To create the histogram you can use unique and histcounts:
[servs, ~, servasint] = unique(servovers);
servhist = histcounts(servasint, [1:numel(servs)+1]);
bar(servhist);
set(gca, 'XTickLabel', servs);
set(gca, 'XTickLabelRotation', 45);
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