How to count the total number of occurrences of each digit avoiding the first elements of each cell?

Suppose I have a cell array

C = {[1; 4; 7]; [2; 5; 8; 9]; [3; 4]};
c{:}
ans = 
1
4
7
ans =
2
5
8
9
ans=
3
4

   % where any digit won't repeat in the individual cell.
   % There are 4 stages in this cell array. 
   % first stage elements are 1, 2, 3
   % second stage elements are 4, 5, 4
   % third stage elements are 7,8
   % fourth stage elements are 9

I need to count the total number of occurrences of each digit except stage 1 that means by avoiding the first elements of each cell. Expected output:

Digit | Number of occurrences
  4        2
  5        1
  7        1
  8        1
  9        1

[Guillaume]

Please don't ask the same question twice, thus wasting everybody's effort.

Duplicate of how-to-count-the-total-number-of-occurrences-of-each-digit-in-cell-arrays

Answer 1

[Nick]

You could do the following if you don't mind using some for loops

 % example data  
C = {[1; 4; 7]; [2; 5; 8; 9]; [3; 4]};

 % get the highest digit to make an array in which you store your count  
highestDigit = max(cell2mat(C));
countArray = zeros(2, highestDigit);
 % replace the second row with the digits
countArray(2,:) = 1:highestDigit;

 % then loop over the cell array
for ii = 1:numel(C)
  digits = C{ii}(2:end); % filter out the first digit
  for jj=1:numel(digits)
     countArray(1,digits(jj)) = countArray(1,digits(jj)) + 1; % add one every time it occurs
  end
end

% remove the zeros
maskZeros = countArray(1,:)~=0;
countArray = countArray(:,maskZeros);

% print the result
fprintf('Digit  |  Number of occurrenced \n')
for ii = 1:length(countArray)
 fprintf('%d             %d \n',countArray(2, ii), countArray(1,ii)); 
end

[Md Shahidullah Kawsar]

Thanks. How can I plot the histogram of the number of occurrences?

[Nick]

It depends how you want to display it:

Only showing the numbers that occurred you can do

figure;
binNames = strsplit(num2str(countArray(2,:)),' ');
h = histogram('Categories', binNames,'BinCounts', countArray(1,:));

Or if you want to show a real histogram by not removing the zeros. Just remove the following lines

maskZeros = countArray(1,:)~=0;
countArray = countArray(:,maskZeros);

and then add this command the end.

binEdges = [0, countArray(2,:)]+0.5;
h = histogram('BinEdges', binEdges,'BinCounts', countArray(1,:));

When first starting its always handy to explore the properties of the object handle (h) so you know how you can customize your histogram.